Advancements in Developing Strategies for Sterilizing and …downloads.hindawi.com/journals/bmri/2017/6096134.pdf · 2019. 7. 30. · by using specially designed zinc-finger nucleases

Review ArticleAdvancements in Developing Strategies for Sterilizing andFunctional HIV Cures

Wei Xu1 Haoyang Li1 QianWang1 Chen Hua1 Hanzhen Zhang1

Weihua Li2 Shibo Jiang123 and Lu Lu1

1Key Laboratory of Medical Molecular Virology of Ministries of Education and Health School of Basic Medical Sciences andShanghai Public Health Clinical Center Fudan University Shanghai 200032 China2Key Laboratory of Reproduction Regulation of NPFPC SIPPR IRD Fudan University Shanghai 200032 China3Lindsley F Kimball Research Institute New York Blood Center New York NY 10065 USA

Correspondence should be addressed to Shibo Jiang shibojiangfudaneducn and Lu Lu lulfudaneducn

Received 22 January 2017 Accepted 4 April 2017 Published 26 April 2017

Academic Editor Himanshu Garg

Copyright copy 2017 Wei Xu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Combined antiretroviral therapy (cART) has been successful in prolonging lifespan and reducing mortality of patients infectedwith human immunodeficiency virus (HIV) However the eradication of latent HIV reservoirs remains a challenge for curingHIV infection (HIV cure) because of HIV latency in primary memory CD4+ T cells Currently two types of HIV cures are indevelopment a ldquosterilizing curerdquo and a ldquofunctional curerdquo A sterilizing cure refers to the complete elimination of replication-competent proviruses in the body while a functional cure refers to the long-term control of HIV replication without treatmentBased on these concepts significant progress has been made in different areas This review focuses on recent advancements andfuture prospects for HIV cures

1 Introduction

Combined antiretroviral therapy (cART) has enabled thesustained control of viremia in virtually all human immun-odeficiency virus (HIV) patients It has prolonged lifespanimproved quality of life and transformed HIV infectionfrom a fatal disease into a chronic infectious disease [1ndash3] However individuals on cART require lifelong adher-ence and withdrawal of the therapeutic regimens inevitablyleads to rebound of HIV replication In addition long-term medication may increase the risk of adverse reactionssuch as immune system disorders nervous system disordersand increase of viral reservoirs Therefore new theory andmethods are urgently needed for the development of aneffective HIV cure

The key obstacle to an HIV cure is latent HIV reservoirswhich are mainly composed of resting memory CD4+ Tcells in the early stages of HIV infection [4 5] Duringtranscription of the provirus DNA is inhibited therebyallowing the provirus to evade clearance by the host immune

system Although cART is directed against cells that replicateHIV it has no effect on cells carrying latent HIV reservoirsdemonstrating the ineffectiveness of cART as an HIV cure

Two types of HIV cures are under development theldquosterilizing curerdquo and the ldquofunctional curerdquo A sterilizing curerefers to the complete elimination of replication-competentproviruses The famous ldquoBerlin patientrdquo represents one suc-cessful case of a sterilizing cure Timothy Brown the so-called Berlin patient positive for bothHIV and acutemyeloidleukemia (AML) received two stem cell transplants froma donor homozygous for the CCR5delta32 mutation TheCCR5delta32 mutation stem cell is a kind of CCR5-deficientcell which renders cells highly resistant to HIV-1 infectionEight years later he appears to be free of both HIV and AML[6] However it is very difficult to find donors with humanleukocyte antigens (HLA) identical to those of recipients forCCR5 Delta32Delta32 stem cell transplantation while themortality rate of transplant surgery is up to 30 Thus thistreatment model is difficult to reproduce However otherstrategies to carry out an effective sterilizing HIV cure are

HindawiBioMed Research InternationalVolume 2017 Article ID 6096134 12 pageshttpsdoiorg10115520176096134

2 BioMed Research International

Eliminate HIV-DNAby genome editing

Normal cellular DNA

Latent cell

Provirus

(a)

Normal receptor DNA

Modify receptor by genome editing

Modified receptorsprotect cells from

HIV infection

Uninfected cell

Modified receptor DNA

(b)

Figure 1 Two major strategies for HIV cure by using genome editing (a) Gene therapy strategies to eradicate HIV reservoirs Using ZFNTALENS or CRISPR to eliminate the HIV provirus in latent cells (b) Gene therapy strategies to prevent susceptible cells fromHIV infectionUsing gene editing to modify the receptor of susceptible cells and protect them from HIV infection

under development such as genome editing gene therapyand shock and kill [7 8]

Functional cure refers to the long-term control of HIVreplication which involves maintaining a normal CD4+ Tcell count and HIV replication below a detectable level [9]ldquoHIV controllersrdquo are considered to be those patients whoseHIV RNA is kept below the clinical baseline for a long periodwithout cART Studies on ldquoHIV controllersrdquo are expected toprovide important clues for the development of therapiesor strategies for functional HIV cure such as therapeuticvaccines and vector-mediated gene transfer therapy [10 11]Moreover the human genome has integrated a large numberof retrotransposon sequences over the course of evolutionandHIVmay coexist with humans if it is restricted From thisperspective the functional cure is as important as the steril-izing cureThis article will review the advancements in devel-oping strategies for both sterilizing and functionalHIV cures

2 Strategies for Sterilizing HIV Cure

21 Gene Therapy to Eradicate HIV Reservoirs Three majorgenome editing technologies have been used to eliminatethe HIV provirus including Zinc-finger nuclease (ZFN)technology the effects of transcription activator-like effector(TALENS) and clustered normal interspaced short palin-dromic repeat (CRISPR) and CRISPR-associated protein 9(CRISPR-Cas9) technologies [12ndash14] In contrast to normalcells HIV reservoir cells harbor a latent reservoir of HIVproviruses with the potential for replication Therefore ldquotar-geted eliminationrdquo of these cells will reduce their ability tocreate HIV viral offspring Accordingly some researchers usegenome editing technologies to mutate the target fragmentsof HIV proviruses in latent reservoir cells (Figure 1(a))

In 2011 Wayengera used ZFN technology to abrogatethe function of the pol gene However the modification ofthe coding sequence could not completely silence the HIV

provirus and the unmodified viral genes were still expressedunder the effect of long terminal repeat (LTR) [15] Qu etal then presented a possible alternative therapeutic approachby using specially designed zinc-finger nucleases (ZFNs)to target a sequence within the LTR to directly mediatea deletion of the HIV provirus from the HIV-integratedhumanT cell genome [16]The target sequencewas conservedacross all HIV clades making it suitable for a variety of HIVgenotypes Moreover they found that effective excision ofLTR could clear full-length HIV-1 proviral DNA In theirexperiment they observed that the frequency of excisionwas 459 in infected human cell lines after treatment [17]In 2014 the team used the LTR U3 region as a target ofZFN technology and successfully cleared about 30 of HIVproviruses from infected cells

One major challenge for both ZFN and TALENs is theexpense and labor involved A new genome editing toolCRISPRCas9 has recently entered the spotlight From 2013to 2014 two groups edited the integrated LTR on the cellgenome using the CRISPRCas9 system respectively andsucceeded in suppressing LTR-controlled gene transcription[18] The CRISPRCas9 system mutates not only HIV DNAin T cells but also some other HIV reservoir cells such asmicroglial cells and monocytes-macrophages FurthermoreCRISPRCas9 was verified to eliminate multiple HIV DNAcopies [18] Studies show the potential application of theCRISPRCas9 system in curing HIV infection By makingsite-specific DNA double-stranded breaks the CRISPRCas9system is also a unique antiviral defense system againstforeign plasmids and viruses A recent study reported that theCRISPRCas9 system interrupted the latently integrated viralgenome thereby forming a barrier against viral infectionsuggesting the CRISPRCas9 system as a new therapeuticstrategy [19]

Another study revealed that the CRISPRCas9 gene edit-ing technique could prevent the HIV virus from infecting

BioMed Research International 3

T cells ACRISPR-Cas9 genome editor introduced amutationin embryos that caused dysfunction of the CCR5 gene[20] Meanwhile the Kaminski team found that this geneediting system could remove all HIV-1 proviral DNA copiesfrom latently infected human CD4+ T cells by using aconvenient human T-lymphocytic cell culture model andCD4+ T cells obtained from HIV-1+ patients In this studyit was confirmed that this technique not only removed theproviral DNA from T cells but also subsequently protectedthem from new HIV-1 infection This research team alsoaddressed the issue of off-target effects and toxicity [21] In2015 Strong et al used transcription activator-like effectornucleases (TALENs) to target the LTR of the HIV-1 provirusthus preventing the expression of LTR downstream genes[17]

Although the gene therapy strategy for HIV provirusDNA is a direct method for eliminating the HIV reservoirtwo challenges remain First all of these studies were basedon in vitro experimentation or nonhuman primates but nohuman experimental data essentially because no efficientvector could transfer these elements to the targeted geneWithout specific targeted introduction the editing effect willbe minimized since all cells can potentially take up theseelements Second genome editing technologies have varyingdegrees of ldquooff-targetrdquo effects and although no cytotoxicityand cell death have been observed in the primary cells thispotential risk cannot be completely ruled out

22 Gene Therapy to Prevent Susceptible Cells from HIVInfection Successfully curing HIV infection in the ldquoBerlinpatientrdquo case resulted from the transplantation of CCR5Delta32Delta32 stem cells [22] Thus if latent HIV-infectedcells lose susceptibility newly infected cells will be limitedand a ldquocleanrdquo population of CD4+ T cells will be estab-lished [23 24] Inspired by the ldquoBerlin patientrdquo Perez etal used engineered zinc-finger nucleases (ZFNs) to disruptendogenous CCR5 in primary human CD4+ T cells and 50of CCR5 alleles of these cells were mutated (Figure 1(b))The modified CCR5 genotype could be inherited in theprocess of amplification of CD4+ T cells in vitro Thegenetic mutation of CCR5 provided stable and heritableprotection against HIV infection in a NOG model of HIVinfection such that engrafted ZFN-modified mice had lowerviral loads than mice with wild-type CD4+ T cells [25]Tebas et al enrolled 12 patients with chronic HIV infectionwhile receiving highly active antiretroviral therapy (HAART)[26] Six of the patients were infused with 10 billion CD4+T cells for four weeks followed by withdrawal of cARTAlthough HIV titers rebounded after cART withdrawal thenumbers of CD4+ T cells in peripheral blood of all patientswere significantly higher than those in the control groupAdditionally the viral titers in most patients continued todecrease after reaching a peak at 16 weeks and the HIVRNA level of one treated patient became undetectable at theendpoint of the test These results suggested that improvingthe efficiency of ZFN editing and obtaining double mutationsof CCR5 alleles might significantly improve the therapeuticeffect Only one patient had fever chills joint pain and backpain after infusion [26]

Recently Badia et al reported a new strategy target-ing the region of 32-deletion polymorphism in the CCR5gene (CCR5Δ32) which mimicked the naturally occurringCCR5Δ32 polymorphism in the ldquoBerlin patientrdquo to fur-ther confirm the safety of this therapy [27] Based on thereconstruction of CCR5 therapy in CD4+ T cells somepatients could be withdrawn from cART after a certainperiod seeming to indicate a dawn of functional cure Thechallenge of this therapy is that the adoptively mature CD4+T cells have limited replicative potential Thus the depletionof infusing CD4+ T cells in peripheral blood led to virusrebound Therefore some researchers are studying how tomake HIV-infected individuals continue to produce CCR5-modified T cells For instance Holt et al modified CD34+human hematopoietic stemprogenitor cells (HSPCs) by ZFNtargeting to CCR5 in vivo and transplanted the modifiedcells into nonobese diabeticsevere combined immunodefi-cientinterleukin 2r120574null (NODSCIDIL2r120574nullNSG)micewhile the control mouse group received untreated HSPCsWhen challenged with a CCR5-tropic HIV virus the controlmouse group showed profound CD4+ T cell loss [28] In arecent report Li et al mobilized CCR5 gene expression inHSPCs using a recombinant adenoviral vector encoding aCCR5-specific pair of zinc-finger nucleases Hematopoieticstem cell transformation and autologous transplantation areexpected to achieve a viable functional cure [29] Theo-retically mobilizing CCR5 gene expression renders HIV-susceptible cells less susceptible to HIV infection Modifiedhematopoietic stem cells can continuously produce anti-HIVcells including HIV target cells such as CD4+ T lymphocytesand macrophages However hematopoietic stem cells caneasily lose their differentiation ability during in vitro cultureThemain challenges for the technology are how to efficientlyaccurately and securely deliver stem cells into bone marrow

On the other hand it is still debatable whether themodification of CCR5 can inhibit HIV replication of C-X-C chemokine receptor type 4 (CXCR4) tropism in vivo[29] In order to avoid preexisting virus strains that useCXCR4 rebound Didigu et al used zinc-finger nucleases(ZFNs) to simultaneously inactivate the CCR5 and CXCR4genes They observed that the modified cells could inhibitvirus replication for both CCR5 and CXCR4 tropism virusin humanized mouse models [30] In general the result ofthe ldquoBerlin patientrdquo indicates that the strategy of receptorgene editing is viable to some degree And yet it is farfrom preclinical or clinical trials Moreover transformationamplification and reinfusion of T cells or hematopoietic stemcells in vitro are very complicated processes and treatmentcost is high making implementation uncertain Although anumber of Phase I clinical trials have been conducted thistreatment regime is still out of reach forHIV-infected personsin developing countries In addition some studies suggestthat modifications of CCR5 may reduce the ability of theimmune system to defend against pathogens Also whetherCXCR4 modification affects its normal function requiresfurther study [31]

23 Shock and Kill Strategy Complete removal of HIV-1viruses must eliminate infectious virions inside and outside


the cell but also eliminate the provirus gene hidden in theinfected cells and latent reservoirs Using clinical drugs goodresults have been achieved for the virus outside the cellHowever a true HIV cure will only result from the removalof HIV latent cells which are those cells that remain ldquosilentrdquoor nonproductive after integration of HIV-1 genomes Withthe exception of the HIV latent genome these cells showlittle difference from normal cells making them difficult todiscover and eradicate However HIV-1 proviruses in latentcells can be reactivated under certain conditions resulting ina viral rebound after drugwithdrawal [32] Importantly latentcells have a long half-life in vivo Studies have shown that thehalf-life of latent cells is about 439 months in vivo Even inpatients treated with HAART a period of 73 years is requiredto completely remove latent cells meaning that we cannotcure HIV with the existing drugs in a typical lifetime [33]In order to cure HIV the research community is now focusedon approaches to clear persistent HIV infection also knownas the ldquoshock and killrdquo strategy [34] This approach activateslatent cells and then uses existing HIV drugs to inhibit newgeneration of HIV infectious viruses Two kinds of drugs arerequired One is considered a ldquoshock agentrdquo to activate latentHIV cells and the other is a ldquokill agentrdquo which blocks thereactivation of the latent virus and protects cells from formingnew latency

231 ldquoShockrdquo Agents Several functional agents have thepotential to revert HIV-1 latency including (a) histonedeacetylase (HDAC) inhibitors (b) bromodomain andextraterminal (BET) inhibitors (c) DNA methyltransferase(DNMT) inhibitors (d) protein kinase C (PKC) activators(e) cytokines and chemokines and (f) unclassified agents[35 36]

Among the ldquoShockrdquo agents HDAC inhibitors havebeen widely studied in the past decade HDAC inhibitorssuch as valproic acid (VPA) butyric acid trichostatin AvorinostatSAHA panobinostat entinostat givinostat andromidepsin have been well characterized both in vivo andin vitro (Table 1) VPA was the first HDAC inhibitor to reachclinical trials However it was nonspecific and limited effectswere observed when activating latent cells [37] Vorinostatis the first HDAC inhibitor approved by the FDA for thetreatment of cutaneous T cell lymphoma Reporting theirfindings in Nature in 2012 Archin et al found that asingle dose of vorinostat was effective in disrupting HIV-1latency in patients with long-term treatment of HAART andsignificantly increasing RNA expression (mean increase 48-fold) [38] Moreover their finding showed the feasibility ofusing HDAC inhibitors as a ldquoshock agentrdquo to activate HIVlatency in cells HDAC inhibitors have several advantagesover other latency reactivators in that most have been usedas anticancer therapies whose pharmacological and toxico-logical properties are quite clear Valproic acid (VPA) butyricacid vorinostat trichostatin A and panobinostat have beenapproved by the FDA for the treatment of cancer Someminoror self-limiting adverse effects have been reported for HDACinhibitors including nauseavomiting and fatigue [39]

In addition to HDAC inhibitors BET inhibitors DNMTinhibitors PKC activators cytokines and chemokines and

unclassified agents have been shown to reverse HIV-1 latencyThe representative agents for each groups are listed asfollows JQ1 is a BET inhibitor which binds to bromod-omains and inhibits the function of Brd4 [40] Moreover JQ1was found to synergize with other agents such as HDACinhibitors to reactivate HIV from latency [41] Currently athienotriazolodiazepine compound OTX015 was reportedto effectively reactivate latent provirus in a model of HIVlatency with EC

50value much lower than JQ1 [42] Likewise

5-aza-21015840deoxycytidine (Aza-CdR) a DNA methyltransferaseinhibitor which has been approved by FDA for the treatmentof myelodysplastic syndrome has a synergistic effect withNF-120581B activators [43] Recently a new protein kinase C(PKC) activator Ingenol B has been used to reactivateHIV latency in vitro Because Ingenol B has minimal celltoxicity it is more potent than SAHA and JQ1 [44] Severalnovel unclassified agents such as ZF-VP64 and TALE1-VP64 can also significantly reactivate HIV-1 expressionfrom latently infected cells [45 46] ZF-VP64 a zinc-fingertranscription factor is composed of designer zinc-fingerproteins and the transcriptional activation domain VP64Similar to ZF-VP64 TALE1-VP64 consists of a DNA-bindingdomain and the herpes simplex virus-based transcriptionalactivator VP64 domain Both of these are able to specif-ically and effectively reactivate latent HIV-1 transcriptionin vitro [45 46] Importantly combinations of reagentswith different mechanisms of action have shown efficacyFor example the nucleoside transport inhibitor dilazepHDAC inhibitor MC1293 and arsenic trioxide (As2O3) allsynergistically reactivate latent HIV-1 with other activatorsproviding a new HIV latency reactivation strategy [47ndash49](Table 1)

232 ldquoKillrdquo Agents Besides current clinical anti-HIV drugssuch as cocktail therapy ldquokillrdquo agents can be used to clearvirus-producing cells These agents include therapeutic vac-cines broadly neutralizing antibodies (bNAbs) and nonneu-tralizing antibodies

Studies have shown that while HAART suppresses HIVreplication it cannot eliminate the latent virus MoreoverHAART also fails to kill infected CD4+ T cells after latentviruses are reactivated Therefore even though new virusgeneration can be inhibited by HAART reactivated latentHIV virus can still survive to produce new virus and an HIVcure will still not be achieved

Therefore therapeutic vaccines have been proposed withthe hope of using them to induce HIV-specific cytotoxic Tlymphocytes (CTL) to kill the reactivated latent cells HIV-1-specific CTLs which could be stimulated by specific antigensare a major component of viral eradication [50] In additionthese can be obtained by genetic engineering methods invitro such as transforming peripheral CD8 lymphocytes intoHIV-1-specific CTLs by using lentiviral vectors encoding anHIV-1-specific TCR (T cell receptor TCR) [51] Howeverrecent studies have shown that it is very difficult to induce alarge number of highly efficient and specific CTLs in patientswith severe HIV AIDS in vivo and that its effect on thekilling and scavenging of latent library cells after activationis still controversial [52 53] Most patients receiving cART in


Table1Re

agentsto

reactiv

ateH

IV-1fro

mlatency

Latencyreactiv

ating

reagents

Mechanism

Mod

elAd

vantageo

rdisa

dvantage

Reference

Valproicacid

(VPA

)HDAC

inhibitors

Clinical

Weakandno

nspecific

[87]

Butyric

acid

HDAC

inhibitors

Clinical

Approved

bytheF

DA

[88]

Vorin

ostat

(SAHAM

K0683)

HDAC

inhibitors

ACH-2U

1J-LAT

restin

gCD

4+cells

Approved

bytheF

DA

[3989]

Givinostat

HDAC

inhibitors

HIV-in

fected

celllin

esC

linical

Superio

rtoVPA

[90]

Pano

bino

stat

HDAC

inhibitors

ClinicalH

IV-in

fected

celllin

esLo

wer

toxicity

[3991]

Apicidin

Histon

emod

ificatio

nA106celllin

eSynergizew

ithtricho

statin

A[92]

Scrip

taid

Increasin

gthea

cetylatio

nlevelofh

iston

esH3

andH4

JurkatTcelllin

eLo

wer

toxicity

[93]

MC1

293

HDAC

inhibitor

Latencycelllin

esLo

wer

toxicitycomparedto

tricho

statin

A[47]

M344

HDAC

inhibitor

JurkatTcell

Anim

portantrolefor

histo

nemod

ificatio

ns[94]

As2O

3Affectingthetranscriptio

nfactorsa

ndpathways

JurkatTcell

Synergisticallywith

prostratin

orVPA

[48]

OTX

015

Activ

atingNF-kapp

aBCell

EC50

valuelow

erthan

JQ1

[42]

Entin

ostat(MS275)

Inhibitin

gHDAC

1and

HDAC

3A7cell

Cytotoxicitylower

than

SAHA

[95]

Romidepsin

HDAC

inhibitor

ClinicalH

IV-in

fected

celllin

esSafe

[96]

JQ1

BETinhibitor

Celllines

Aversatile

chem

icalscaffoldbind

ingto

itsbrom

odom

ains

[40]

I-BE

T151

BETinhibitor

Tcells

from

cART

avire

micpatients

P-TE

Fb-releasin

gagents

[97]

MS417

BETinhibitor

J-Latcelllinesprim

aryCD

4+Tcells

ReleasingBR

D4fro

mthe51015840LT

R[97]

Interle

ukin

(IL)-2

Cytokinesa

ndchem

okines

HIV-1-infected

CD4+

Tcells

With

limitedsuccess

Interle

ukin

(IL)-7

Cytokinesa

ndchem

okines

Perip

heralblood

mon

onuclear

cells

Increasin

gviralprodu

ctionin

prod

uctiv

elyinfecting

cells

with

outd

isrup

tingthelatency

[9899]

Aza-C

dRDNMTinhibitors

Latentlyinfected

cells

AnFD

Aapproved

drug

[43]

Chaetocin

DNMTinhibitors

JurkatTcells

Increasin

gHIV

expressio

nwith

outsignificanttoxicity

[100]

HMTi

3-deazaneplano

cinA

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

TargetingHKM

Tenhancer

ofZe

ste2

[101]

BIX-

01294

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

Synergisticactio

nthefi

rstH

MTinhibitoru

sedto

reactiv

ateH

IV-1in

vitro

[102]

Ingeno

lBPK

Cactiv

ators

J-LatA

1cell

Morep

otentthanprostratinSAHAandJQ

1[44]

HMBA

P-TE

Fbactiv

ators

RestingCD

4+cells

Overcom

ingbarriersto

LTRexpressio

n[103]

Disu

lfiram

Unclassified

agents

CD4+

cells

Clinicaltrial

ZF-VP6

4Specificb

inding

tothe51015840-LTR

prom

oter

Latentlyinfected

cells

With

outalterin

gcellproliferatio

nor

cellcycle

progression

[45]

TALE

1-VP6

4Transcrip

tionactiv

ator-like

effector

C11and

A106cells

Nodistrib

utionof

cellproliferatio

nor

cellcycle

[46]

Dilazep

Nucleosidetranspo

rtinhibitor

JurkatTcell

Synergisticallyreactiv

ated

transcrip

tionwith

valproic

acid

[49]


the chronic phase have a presence of CTL immune escapemutant In fact these mutant cells are the reason for virusrebound after cART This phenomenon also suggests thatmost latent cells have a certain ability to escape CTL beforeactivation [52] Therefore the strategy of inducing specificCTLs by therapeutic vaccine and clearing the activated latentlibrary cells remains a challenge

Recently Halper-Stromberg et al found that combi-nations of inducers and bNAbs could interfere with theestablishment of a silent reservoir in humanized mice with-out viral rebounding after drug withdrawal The resultsshowed that 57 of the hu-mice treated with antibodies pluscombination inducers failed to rebound by the terminal point[54] This research shows some promise for this therapy inthe activation (shock) step as well as the importance of theapplication of antibodies in the eradication (kill) step [55ndash57] At the same time the study also found that the Fcregion of neutralizing antibody plays an indispensable role inHIV eradication possibly through Fc-mediatedmechanismssuch as antibody-dependent cellular cytotoxicity (ADCC)For instance activated HIV cell-surface expression of theHIV envelope protein Env can be recognized by bNAbs AlsoFc segment binding to Fc receptors on NK cells can killlatent cells These results suggest that Fc function and Fc-mediated ADCC can be used to design drugs able to killactivated HIV latent cells Subsequently several studies haveshown that ADCC may play an important role in killingthe reactivated latent cells [58] In addition their resultsshowed that about 40 of mice had viral rebound after drugwithdrawal suggesting that the use of neutralizing antibodiesalone would face limitations but that further modificationand optimization would enhance their ability to kill latentcells and eliminate the latent reservoir

24 Strategies with Yet-to-Be Known Mechanisms WhileHIV neutralizing antibodies can specifically neutralize HIVinfection or inactivate HIV-infected cells some non-anti-HIV antibodiesmay also be involved in the clearance of HIV-infected cells through some yet-to-be known mechanismsA recent study showed that use of a monoclonal antibody(mAb) against 120572

41205737integrin in combination with ART

resulted in the maintenance of low viral loads and normalCD4+ T cell counts in simian immunodeficiency virus- (SIV-) infected rhesus macaques for more than 9 months afterthe withdrawal of ART [59] Anti-120572

41205737mAb contributes

to controlling viremia and reconstituting immune systemsalthough the mechanism is unknown This finding offersa new hypothesis for a cure that will be tested in thefuture Interestingly although anti-120572

41205737mAb does not have

SIV neutralizing activity it significantly promotes gp120V2-specific antibody responses which played a key rolein reducing the rate of HIV infection in RV144 clinicaltrials [60] Therefore we proposed that an HIV prophylacticand therapeutic vaccine could be designed by combininganti-120572

41205737mAb with a V2-containing antigen in gp120 for

induction of strong V2-specific antibody responses againstHIV-1 infection because (1) both V2-specific B cell receptor(V2-BCR) and 120572

41205737integrin are expressed on B cells (2)

binding of V2-containing antigen (such as gp120) to 12057241205737

integrin would block its binding to V2-BCR and (3) blockingV2-containing antigen binding to 120572

41205737integrin by anti-120572

41205737

mAb would allow the V2-containing antigen to bind withV2-BCR on B cells to induce V2-specific antibody responsesagainst HIV-1 infection [61]

3 Strategies for Functional Cure

31 Vector-Mediated Gene Transfer Therapy to Achieve Func-tional Cure Because existing HIV prophylactic vaccinesfail to stimulate the immune system to generate bNAbsresearchers administered gene vectors named vectoredimmunoprophylaxis (VIP) to animals to achieve long-termexpression of bNAbs in the treated animals The adeno-associated virus (AAV) is the most common vector its safetyand efficiency of gene expression have been fully verified[62ndash64] Balazsrsquo group injected AAV serotype 8 (AAV8) witha bNAb gene into humanized mice [65] Later Horwitz etal injected 25 times 1011 genomic copies of bNAb 10-1074-expressingAAV into themuscles of theHIV-infected human-ized mice pretreated with both cART and immunotherapies[66] Results showed that nearly half of the mice exhibiteda suppressed viral load after cART withdrawal The samegroup has tested another bNAb 3BNC117 in simian humanimmunodeficiency virus- (SHIV-) infected macaques andHIV-1-infected patients They found that a single injectionof 3BNC117 resulted in long-term (sim13 weeks) protectionof macaques against repeated SHIV challenges [67] Moreinterestingly 3BNC117 infusion could significantly improveneutralizing responses to heterologous tier 2 viruses in almostall study HIV-1-infected patients tested suggesting that3BNC117-mediated immunotherapy enhances host humoralimmunity against HIV-1 [67ndash70]

Although escape mutations occurred during the bNAbtreatment these studies have proven that the ldquogene trans-plantrdquo strategy of bNAbs could become an acceptable sub-stitute for cART for the first time [65ndash67] The researchalso points a direction for the ldquogene transplantrdquo strategyagainst HIV which involves introducing multiple existingbNAbs into the body at the same time or finding andusing super bNAbs targeting all genotypes and mutants toovercome strain diversity and escape mutants The formerrequires gene transplantation many times over and may notnecessarily preventHIV escapemutants in the long term [65]In contrast the latter ismore ideal but it is difficult to find thesuper bNAbs that can avoid escape mutation and neutralizeall HIV isolates which is the key obstacle to prevention anda functional cure of HIV [67]

New research is expected to solve this problem Gardneret al created an immunoadhesin form of CD4 named eCD4-Ig which is comprised ofCD4-Ig andCCR5mim1 fused to thehuman IgG1 Fc domain [63] In eCD4-Ig the sulfopeptideCCR5mim1 was fused to the C terminus of CD4-Ig Thiscombination prohibits gp120 from interacting with CD4 andthe coreceptor-binding site on the surface of the cells thusit functionally neutralizes the virus eCD4-Ig exhibits highaffinity and neutralizing ability for all isolates ofHIV-1 as wellas mutant strains resistant to other neutralizing antibodiesIt can even neutralize HIV-2 and SIV whose neutralizing


effect has previously been beyond all bNAbs All genotypes ofHIV need to interact with the CD4 molecule and coreceptormolecule to enter cells Therefore it was estimated that theHIV-resistant mutants of eCD4-Ig were less prone to occurOn the other hand eCD4-Ig had a stronger ability to mediateADCC than the broadly neutralizing antibody b12 To reducethe immunogenicity of eCD4-Ig in the animal experimentsGardner et al substituted the D1D2 domain of CD4 fromhumans into the CD4-D1D2 of rhesus macaques to get rh-eCD4-Ig In the six challenge experiments of SHIV duringthe period all rhesus macaques in the treatment group werefully protected The aim of the challenge experiments was toprove directly that eCD4-Ig had been synthesized and wasable to prevent new infection Applying the gene transplantof eCD4-Ig to HIV-infected individuals was expected toimprove performance better than the gene transplant ofexisting bNAbs since eCD4-Ig can mediate ADCC withbroadly efficient neutralization

In recent years many immunoadhesins that share func-tions in common with eCD4-Ig have been created 2DLTwhich was created by the combination of the D1D2 domainof the CD4 molecule in the human body and polypeptideHIV entry inhibitor T1144 inhibits and inactivates multipleclades of HIV isolates with high efficiency [71] This proteinis also considered an HIV protein inactivator because itwas proved to inactivate free HIV virions Furthermorethe 2DLT protein bound specifically with gp120 and gp41on the surface of HIV-1 virions and destabilized the gp41prehairpin fusion intermediate induced by CD4 domainsthereby significantly reducing sCD4-mediated enhancingeffects on HIV-1 infection and providing a new solution forCD4-induced infection Further study also showed that com-bining 2DLT with clinically used anti-HIV drugs includingHIV entry inhibitors nucleoside and nonnucleoside reverse-transcriptase inhibitors (NRTIs and NNRTIs) and proteaseinhibitors exhibited synergistic anti-HIV-1 activity againstinfection by divergentHIV-1 strains including those resistantto NRTIs and NNRTIs indicating that 2DLT has a potentialto be further developed as a novel anti-HIV-1 drug forfunctional HIV cure [72]

Another example is an engineered bispecific multiva-lent protein 4Dm2m which contains 4 copies of mD122the modified D1 domain in the CD4 molecule targetingthe CD4-binding site (CD4bs) and 2 copies of m364 ahuman neutralizing mAb targeting the coreceptor-bindingsite (CoRbs) also known as CD4-induced site (CD4i) ongp120 [73] Compared with D1D2 mD122 has higher affinityand specificity towards the CD4 binding site in gp120 Basedon its origin from part of the D1 domain on the CD4molecule adverse reactions are expected to be lower incomparison with other immunoadhesins on the D1 and D2domains [71 74] 4Dm2m exhibits highly potent antiviralactivity against a broad spectrum of HIV-1 strains and highstability [74] Unlike eCD4-Ig 4Dm2m does not need severalenzymes to activate it in vivo making 4Dm2m easier to adoptfor gene transplant strategies

Recent findings showed that therapeutic vaccines andcytokines could enhanceHIV-specific cell-mediated immuneresponses but with only partial antiviral effects [75]

A primary difficulty in modifying permissive cells for thestrategies mentioned above lies in their ldquopersonalizationrdquo inthat permissive cells of each patient must be collected andmodified instead of manufacturing and using the same typeof drug as in traditional therapies Consequently researchersasked how one type of drug could be applied to preventpermissive cells from being infected by the virus The bNAbsand HIV entry inhibitors or inactivators are the best candi-dates Since input antibodies and entry inhibitors have a shorthalf-life in vivo requiring long-term injection the treatmentcannot be regarded as anHIV cure strategy However vector-mediated gene transfer does enable exogenous proteins suchas antibodies stably expressed for a prolonged period tobe widely applied in HIV prevention and treatment forHIV cure The approach involves the expression of adequateproteins that can inhibit viral infection stably in the longterm such as bNAbs preventing cells from being infected bythe virus so that the number of normal CD4+ T cells remainsstable The immunoadhesins discussed above are broaderthan bNAbs and unlikely to trigger HIV escape mutantsHowever they are artificial and need long-term expression invivo to realize the functional cure of HIV infection making itnecessary to further study their immunogenicity and adversereactions

32 New Ideas on Therapeutic Vaccines Apart from thecurative strategies introduced above therapeutic vaccineshave been continuously designed essentially because trainingthe immune system with vaccines is safer cheaper andmore efficient than any other medication or treatments Thecommon design routes of therapeutic vaccines are focusedon how to activate the immune system effectively improvingits identification and eradication of HIV and HIV-infectedcells Nevertheless the strategy of using vaccines has thusfar failed to enable the human body to generate enougheffective bNAbs and CTLs Therefore immunogen designneeds the implementation of unconventional strategies Oneexample is the HIV functional protein Tat (transactivator oftranscription) which is an essential protein regulating viralreplication and activation of the latent reservoir It is alsoan important protein toxin in the process of HIV infectionIn recent years vaccine experiments based on Tat as animmunogen have reached phase II clinical trials [76ndash79]Research of the Tat vaccine paves the way for using relativelyconserved HIV ldquononstructural proteinsrdquo as a therapeuticvaccine antigen [13]

The N-terminal heptad repeat (NHR) of the HIV Envprotein gp41 is a conserved sequence of the HIV envelopeOn the surface of HIV NHR is covered by gp120 and isexposed only before membrane fusionThe process proceedsrapidly and the space between the virus membrane and cellmembrane is smallThis limitation of time and spacemakes itdifficult for an IgG antibody (MW=sim150Kd) to access to andbind with NHR [80] although some well-designed immuno-gen containing the epitope of NHR could induce someantibodies in animals with moderate neutralizing activity[81 82] Nevertheless someNHR-specific antibodies becomeneutralizing when incubated at the suboptimal temperatureThis finding suggests that at lower incubation temperature


Transcriptionalactivator

ldquoShockrdquoLatent cell Activated cell Cell death

Naive cell

Humoral immune response

Cellular immune response

ldquoKillrdquo

Protectnaive cells

Vectored immunoprophylaxis

Therapeutic vaccine

ldquoHAARTrdquoInhibition

Infection

ADCC

CTL

New drugs

Figure 2 Potential combination of ldquoShock amp Killrdquo therapeutic vaccine and vectored immunoprophylactic strategies to eradicate HIVreservoirs Specific cytotoxic T lymphocytes (CTL) combined with immunotherapies such as therapeutic vaccines broadly neutralizingantibodies and nonneutralizing antibodies with ADCC effect may lead to eradication of the latent HIV reservoir

the transition from the prehairpin intermediate state to theposthairpin fusion state can be slowed down making itpossible for IgG to access to and bind with the gp41 NHR toblock HIV-1 fusion with the target cell membranes [83]

Recently Wang et al used an N63 peptide derivedfrom the NHR sequence to immunize animals and testedthe IgG antibody isolated from the sera of the immunizedagainst HIV-1 infection They found that the IgG antibodyhad no HIV-1 neutralizing activity However addition ofthe CHR-peptide-based anti-HIV drug enfuvirtide to theNHR-specific antibody made this nonneutralizing antibodybecome neutralizing against infection by divergent HIV-1strains including those resistant to enfuvirtide [84] It is likelythat the interaction between enfuvirtide and NHR sloweddown the membrane fusion process in a way similar to theeffect of lowered temperature making the NHR accessible tothe NHR-specific antibody for mediating inhibition of HIV-1infection

Similarly Richard et al have used small-molecule CD4-mimetic compounds to induce the conformational changeof the HIV-1 Env on HIV-1-infected cells so that these cellsbecome susceptible to ADCC mediated by antibodies insera from HIV-1-infected patients Particularly one of thesmall-molecule CD4-mimetic compounds could sensitizeendogenously infected ex vivo-amplified primary CD4 Tcells to ADCC mediated by autologous effector cells andantibodies in the patientsrsquo seraThus CD4mimetics holds thepromise of therapeutic utility in preventing and controllingHIV-1 infection [85]

The above findings suggest that a CD4 molecule CD4domain or small-molecule CD4 mimetic can trigger theHIV-1 Env conformation change resulting in the exposure ofsome conserved epitopes or region in gp120 or gp41 whichcan serve as a target for antibodies with a neutralizing effectof ADCC effect or for peptide-basedHIV-1 fusion inhibitors

such as enfuvirtide These strategies have potential for use inclinics towards a functional HIV cure

4 Conclusion

In this review we have summarized the advancements indeveloping strategies for (i) a sterilizing HIV cure and (ii)a functional HIV cure To achieve a sterilizing HIV curethree major genome editing technologies including ZFNTALENS and CRISPR-Cas9 have been under developmentto eliminate the HIV provirus in the latently infected cellsAn effective gene therapy strategy is expected to preventsusceptible cells from HIV infection inspired by the suc-cessful cure of HIV infection in the ldquoBerlin patientrdquo Shockand kill strategy utilizing several well characterized ldquoshockagentsrdquo and ldquokill agentsrdquo is still believed to be the mosteffective way to eradicate latent HIV reservoirs and preventHIV from rebounding after treatment is stopped (Figure 2)Besides the HIV-specific CTLs antibody drugs with highADCC effect seem to be a fruitful developmental directionfor the ldquoshock and killrdquo strategy [58 86] To attain functionalHIV cure several highly potent HIV-specific bNAbs havebeen discovered and developed These bNAbs have shownexcellent in vivo efficacy of functional cure of HIV inSHIV-infected NHPs or HIV-infected patients The bNAbsor IgG conjugated with CD4 or CD4 domain(s) so-calledimmunoadhesins have also displayed substantial in vitroand in vivo efficacies against HIV-1 infection To solve theproblems of high expensiveness to produce antibodies andmultiple injections of an antibody due to its short life severalvector-mediated gene transfer therapies designated vectoredimmunoprophylaxis (VIP) have been developed for long-term expression of bNAbs in infected animals or patientsThese strategies seem successful in animal models but thereis still a long way for them to go to reach human clinical


trials Development of therapeutic vaccines for a functionalHIV cure has faced great challenges over the past 10 yearswith difficulties of generating effective HIV-specific CTLsbNAbs and antibodies with ADCC effects Nevertheless theadvancement of developing a functional HIV cure seemsmore rapid and effective than that of a sterilizing HIV cureThe dawn is breaking

Conflicts of Interest

There are no conflicts of interest

Authorsrsquo Contributions

Both Shibo Jiang and Lu Lu contributed equally to this work

Acknowledgments

This work was supported by grants from the National863 Program of China (2015AA020930 to Lu Lu) theNational Natural Science Foundation of China (8137345681672019 and 81661128041 to Lu Lu 81630090 to Shibo Jiang)National Key Research and Development Program of China(2016YFC1000905 to Weihua Li) and the Shanghai Rising-Star Program (16QA1400300)

References

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[2] J Stein M S G Bonsmann and H Streeck ldquoBarriers to HIVcurerdquo HLA vol 88 no 4 pp 155ndash163 2016

[3] J T Kimata A P Rice and J Wang ldquoChallenges and strategiesfor the eradication of the HIV reservoirrdquo Current Opinion inImmunology vol 42 pp 65ndash70 2016

[4] T-W Chun D Engel M M Berrey T Shea L Corey and A SFauci ldquoEarly establishment of a pool of latently infected restingCD4+ T cells during primary HIV-1 infectionrdquo Proceedings ofthe National Academy of Sciences of the United States of Americavol 95 no 15 pp 8869ndash8873 1998

[5] T-W Chun L Carruth D Finzi et al ldquoQuantification of latenttissue reservoirs and total body viral load in HIV-1 infectionrdquoNature vol 387 no 6629 pp 183ndash188 1997

[6] J Lisziewicz E Rosenberg J Lieberman et al ldquoControl ofHIV despite the discontinuation of antiretroviral therapyrdquo NewEngland Journal of Medicine vol 340 no 21 pp 1683ndash16841999

[7] D H Barouch and S G Deeks ldquoImmunologic strategies forHIV-1 remission and eradicationrdquo Science vol 345 no 6193 pp169ndash174 2014

[8] C SpraggHDe Silva Feelixge andK R Jerome ldquoCell and genetherapy strategies to eradicate HIV reservoirsrdquoCurrent Opinionin HIV and AIDS vol 11 no 4 pp 442ndash449 2016

[9] Z Kmietowicz ldquoEarlyHIV treatment led to ldquofunctional curerdquo in14 patients report researchersrdquo BMJ vol 346 Article ID f17592013

[10] J F Okulicz and O Lambotte ldquoEpidemiology and clinicalcharacteristics of elite controllersrdquo Current Opinion in HIV andAIDS vol 6 no 3 pp 163ndash168 2011

[11] L R Cockerham and H Hatano ldquoElite control of HIV is thisthe right model for a functional curerdquo Trends in Microbiologyvol 23 no 2 pp 71ndash75 2015

[12] R Benjamin B K Berges A Solis-Leal O Igbinedion C LStrong and M R Schiller ldquoTALEN gene editing takes aim onHIVrdquo Human Genetics vol 135 no 9 pp 1059ndash1070 2016

[13] G Geng B Liu C Chen et al ldquoDevelopment of an attenuatedTat protein as a highly-effective agent to specifically activateHIV-1 latencyrdquoMolecular Therapy vol 24 no 9 pp 1528ndash15372016

[14] P Limsirichai T Gaj and D V Schaffer ldquoCRISPR-mediatedactivation of latent HIV-1 expressionrdquo Molecular Therapy vol24 no 3 pp 499ndash507 2016

[15] M Wayengera ldquoProviral HIV-genome-wide and pol-gene spe-cific Zinc Finger Nucleases usability for targeted HIV genetherapyrdquo Theoretical Biology and Medical Modelling vol 8 no1 article 26 2011

[16] X Qu P Wang D Ding et al ldquoZinc-finger-nucleases mediatespecific and efficient excision of HIV-1 proviral DNA frominfected and latently infected human T cellsrdquo Nucleic AcidsResearch vol 41 no 16 pp 7771ndash7782 2013

[17] C L Strong H P Guerra K R Mathew N Roy L R SimpsonandMR Schiller ldquoDamaging the integratedHIVproviralDNAwith TALENsrdquo PLoS ONE vol 10 no 5 Article ID e01256522015

[18] X Qu P Wang D Ding et al ldquoZinc finger nuclease anew approach for excising HIV-1 proviral DNA from infectedhuman T cellsrdquo Molecular Biology Reports vol 41 no 9 pp5819ndash5827 2014

[19] H-K Liao Y Gu A Diaz et al ldquoUse of the CRISPRCas9system as an intracellular defense against HIV-1 infection inhuman cellsrdquoNature Communications vol 6 article 6413 2015

[20] X Kang W He Y Huang et al ldquoIntroducing precise geneticmodifications into human 3PN embryos by CRISPRCas-mediated genome editingrdquo Journal of Assisted Reproduction andGenetics vol 33 no 5 pp 581ndash588 2016

[21] R Kaminski Y L Chen T Fischer et al ldquoElimination of HIV-1genomes from human T-lymphoid cells by CRISPRCas9 geneeditingrdquo Scientific Reports vol 6 Article ID 22555 2016

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[23] C W Peterson P Younan K R Jerome and H-P KiemldquoCombinatorial anti-HIV gene therapy using a multiprongedapproach to reach beyond HAARTrdquo Gene Therapy vol 20 no7 pp 695ndash702 2013

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[26] P Tebas D Stein W W Tang et al ldquoGene editing of CCR5 inautologous CD4 T cells of persons infected with HIVrdquoThe NewEngland Journal of Medicine vol 370 no 10 pp 901ndash910 2014

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[36] H-T Shang J-W Ding S-Y Yu T Wu Q-L Zhang and F-J Liang ldquoProgress and challenges in the use of latent HIV-1reactivating agentsrdquo Acta Pharmacologica Sinica vol 36 no 8pp 908ndash916 2015

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[39] J H Elliott F Wightman A Solomon et al ldquoActivation ofHIV transcriptionwith short-course vorinostat inHIV-infectedpatients on suppressive antiretroviral therapyrdquo PLoS Pathogensvol 10 no 11 2014

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[41] N M Archin and D M Margolis ldquoEmerging strategies todeplete the HIV reservoirrdquo Current Opinion in Infectious Dis-eases vol 27 no 1 pp 29ndash35 2014

[42] P Lu X Qu Y Shen et al ldquoThe BET inhibitor OTX015reactivates latent HIV-1 through P-TEFbrdquo Scientific Reports vol6 Article ID 24100 2016

[43] G Fernandez and S L Zeichner ldquoCell line-dependent variabil-ity in HIV activation employing DNMT inhibitorsrdquo VirologyJournal vol 7 article 266 2010

[44] G Jiang E A Mendes P Kaiser et al ldquoReactivation of HIVlatency by a newly modified Ingenol derivative via proteinkinaseC120575-NF-120581B signalingrdquoAIDS vol 28 no 11 pp 1555ndash15662014

[45] P Wang X Qu X Wang et al ldquoSpecific reactivation of latentHIV-1 with designer zinc-finger transcription factors targetingthe HIV-1 51015840-LTR promoterrdquo Gene Therapy vol 21 no 5 pp490ndash495 2014

[46] X Wang P Wang Z Fu et al ldquoDesigned transcriptionactivator-like effector proteins efficiently induced the expres-sion of latent HIV-1 in latently infected cellsrdquo AIDS Researchand Human Retroviruses vol 31 no 1 pp 98ndash106 2015

[47] X Qu H Ying X Wang et al ldquoHistone deacetylase inhibitorMC1293 induces latent HIV-1 reactivation by histone modifica-tion in vitro latency cell linesrdquoCurrent HIV Research vol 11 no1 pp 24ndash29 2013

[48] PWang X Qu XWang et al ldquoAs2O3 synergistically reactivatelatent HIV-1 by induction of NF-120581Brdquo Antiviral Research vol100 no 3 pp 688ndash697 2013

[49] H Zeng S Liu P Wang et al ldquoDilazep synergistically reacti-vates latent HIV-1 in latently infected cellsrdquo Molecular BiologyReports vol 41 no 11 pp 7697ndash7704 2014

[50] L Shan K Deng N S Shroff et al ldquoStimulation of HIV-1-specific cytolytic T lymphocytes facilitates elimination of latentviral reservoir after virus reactivationrdquo Immunity vol 36 no 3pp 491ndash501 2012

[51] A JosephH Z Jian A Follenzi et al ldquoLentiviral vectors encod-ing human immunodeficiency virus type 1 (HIV-1)-specific T-cell receptor genes efficiently convert peripheral blood CD8T lymphocytes into cytotoxic T lymphocytes with potent invitro and in vivo HIV-1-specific inhibitory activityrdquo Journal ofVirology vol 82 no 6 pp 3078ndash3089 2008

[52] K Deng M Pertea A Rongvaux et al ldquoBroad CTL responseis required to clear latent HIV-1 due to dominance of escapemutationsrdquo Nature vol 517 no 7534 pp 381ndash385 2015

[53] M D Marsden and J A Zack ldquoDouble trouble HIV latencyand CTL escaperdquo Cell Host and Microbe vol 17 no 2 pp 141ndash142 2015

[54] A Halper-Stromberg C-L Lu F Klein et al ldquoBroadly neutral-izing antibodies and viral inducers decrease rebound fromHIV-1 latent reservoirs in humanized micerdquo Cell vol 158 no 5 pp989ndash999 2014

[55] B Liu F Zou L Lu et al ldquoChimeric antigen receptor Tcells guided by the Single-Chain Fv of a broadly neutralizingantibody specifically and effectively eradicate virus reactivatedfrom latency in CD4(+) T lymphocytes isolated from HIV-1-infected individuals receiving suppressive combined antiretro-viral therapyrdquo Journal of Virology vol 90 no 21 pp 9712ndash97242016

[56] W S Lee T A Rasmussen M Tolstrup et al ldquoAnti-HIV-1 ADCC antibodies following latency reversal and treatmentinterruptionrdquo Aids Research and Human Retroviruses vol 32supplement 1 p 405 2016

[57] T C Rodman and F H Pruslin ldquoIdentification of a low-affinitysubset of protamine-reactive IgM antibodies present in normaldeficient in AIDS sera implications for HIV latencyrdquo ClinicalImmunology and Immunopathology vol 57 no 3 pp 430ndash4401990

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[62] S P Fuchs J M Martinez-Navio M Piatak J D Lifson GGao and R C Desrosiers ldquoAAV-delivered antibody mediatessignificant protective effects against SIVmac239 challenge in theabsence of neutralizing activityrdquo PLoS Pathogens vol 11 no 8Article ID e1005090 2015

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[70] T Schoofs F KleinM Braunschweig et al ldquoHIV-1 therapywithmonoclonal antibody 3BNC117 elicits host immune responsesagainst HIV-1rdquo Science vol 352 no 6288 pp 997ndash1001 2016

[71] L Lu C Pan Y Li H Lu W He and S Jiang ldquoA biva-lent recombinant protein inactivates HIV-1 by targeting thegp41 prehairpin fusion intermediate induced by CD4 D1D2domainsrdquo Retrovirology vol 9 article 104 2012

[72] W Xu Q Wang F Yu L Lu and S Jiang ldquoSynergistic effectresulting from combinations of a bifunctional HIV-1 antagonistwith antiretroviral drugsrdquo Journal of Acquired Immune Defi-ciency Syndromes vol 67 no 2 pp 1ndash6 2014

[73] W Chen Z Zhu Y Feng and D S Dimitrov ldquoHumandomain antibodies to conserved sterically restricted regions ongp120 as exceptionally potent cross-reactiveHIV-1 neutralizersrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 105 no 44 pp 17121ndash17126 2008

[74] W Z Chen Y Feng P Prabakaran et al ldquoExceptionallypotent and broadly cross-reactive bispecific multivalent HIV-1inhibitors based on single human CD4 and antibody domainsrdquoJournal of Virology vol 88 no 2 pp 1125ndash1139 2014

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[76] G Mousseau C F Kessing R Fromentin L Trautmann NChomont and S T Valente ldquoThe tat inhibitor didehydro-cortistatin a prevents HIV-1 reactivation from latencyrdquo mBiovol 6 no 4 Article ID e00465-15 2015

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[78] D A Donahue B D Kuhl R D Sloan and M A WainbergldquoThe viral protein tat can inhibit the establishment of HIV-1latencyrdquo Journal of Virology vol 86 no 6 pp 3253ndash3263 2012

[79] S K Song H Li andMW Cloyd ldquoRates of shutdown of HIV-1 into latency roles of the LTR and tatrevvpu gene regionrdquoVirology vol 225 no 2 pp 377ndash386 1996

[80] D C Chan D Fass J M Berger and P S Kim ldquoCore structureof gp41 from the HIV envelope glycoproteinrdquo Cell vol 89 no2 pp 263ndash273 1997

[81] E Bianchi J G Joyce M D Miller et al ldquoVaccination withpeptide mimetics of the gp41 prehairpin fusion intermediateyields neutralizing antisera against HIV-1 isolatesrdquo Proceedingsof the National Academy of Sciences of the United States ofAmerica vol 107 no 23 pp 10655ndash10660 2010

[82] Z Qi C E Pan H Lu et al ldquoA recombinant mimetics ofthe HIV-1 gp41 prehairpin fusion intermediate fused withhuman IgG Fc fragment elicits neutralizing antibody responsein the vaccinated micerdquo Biochemical and Biophysical ResearchCommunications vol 398 no 3 pp 506ndash512 2010

[83] H Golding M Zaitseva E De Rosny et al ldquoDissection ofhuman immunodeficiency virus type 1 entry with neutralizingantibodies to gp41 fusion intermediatesrdquo Journal of Virologyvol 76 no 13 pp 6780ndash6790 2002

[84] Q Wang W Bi X Zhu et al ldquoNonneutralizing antibodiesinduced by the HIV-1 gp41 NHR domain gain neutralizingactivity in the presence of the HIV fusion inhibitor enfuvirtidea potential therapeutic vaccine strategyrdquo Journal of Virology vol89 no 13 pp 6960ndash6964 2015

[85] J Richard M Veillette N Brassard et al ldquoCD4 mimeticssensitize HIV-1-infected cells to ADCCrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 112 no 20 pp E2687ndashE2694 2015

[86] W S Lee T A Rasmussen M Tolstrup et al ldquoAnti-HIV-1 ADCC antibodies following latency reversal and treatmentinterruptionrdquo Aids Research and Human Retroviruses vol 32article 405 2016

[87] G Lehrman I B Hogue S Palmer et al ldquoDepletion of latentHIV-1 infection in vivo a proof-of-concept studyrdquo Lancet vol366 no 9485 pp 549ndash555 2005

[88] K Imai K Yamada M Tamura K Ochiai and T OkamotoldquoReactivation of latent HIV-1 by a wide variety of butyric acid-producing bacteriardquo Cellular and Molecular Life Sciences vol69 no 15 pp 2583ndash2592 2012

[89] F Wightman P Ellenberg M Churchill and S R LewinldquoHDAC inhibitors in HIVrdquo Immunology and Cell Biology vol90 no 1 pp 47ndash54 2012

[90] S Matalon T A Rasmussen and C A Dinarello ldquoHistonedeacetylase inhibitors for purging HIV-1 from the latent reser-voirrdquoMolecular Medicine vol 17 no 5-6 pp 466ndash472 2011

[91] T A Rasmussen M Tolstrup C R Brinkmann et al ldquoPanobi-nostat a histone deacetylase inhibitor for latent-virus reacti-vation in HIV-infected patients on suppressive antiretroviraltherapy a phase 12 single group clinical trialrdquoTheLancet HIVvol 1 no 1 pp E13ndashE21 2014

[92] S G Lin Y H Zhang H Ying andH Zhu ldquoHIV-1 reactivationinduced by apicidin involves histone modification in latentlyinfected cellsrdquo Current HIV Research vol 9 no 4 pp 202ndash2082011


[93] H Ying Y Zhang S Lin Y Han and H-Z Zhu ldquoHistonedeacetylase inhibitor Scriptaid reactivates latent HIV-1 pro-moter by inducing histone modification in in vitro latency celllinesrdquo International Journal of Molecular Medicine vol 26 no2 pp 265ndash272 2010

[94] H Ying Y H Zhang X Zhou et al ldquoSelective histonedeacety-lase inhibitor M344 intervenes in HIV-1 latency throughincreasing histone acetylation and activation of NF-kappaBrdquoPLoS ONE vol 7 no 11 Article ID e48832 2012

[95] F Wightman H K Lu A E Solomon et al ldquoEntinostatis a histone deacetylase inhibitor selective for class 1 his-tone deacetylases and activates HIV production from latentlyinfected primary T cellsrdquo AIDS vol 27 no 18 pp 2853ndash28622013

[96] O S Soslashgaard M E Graversen S Leth et al ldquoThe depsipeptideromidepsin reversesHIV-1 latency in vivordquoPLoS Pathogens vol11 no 9 Article ID e1005142 2015

[97] D Boehm V Calvanese R D Dar et al ldquoBET bromodomain-targeting compounds reactivate HIV from latency via a Tat-independent mechanismrdquo Cell Cycle vol 12 no 3 pp 452ndash4622013

[98] M-C Bowman N M Archin and D M Margolis ldquoPharma-ceutical approaches to eradication of persistent HIV infectionrdquoExpert Reviews in Molecular Medicine vol 11 article e6 2009

[99] C Vandergeeten R Fromentin S DaFonseca et alldquoInterleukin-7 promotes HIV persistence during antiretroviraltherapyrdquo Blood vol 121 no 21 pp 4321ndash4329 2013

[100] W Bernhard K Barreto A Saunders M S Dahabieh PJohnson and I Sadowski ldquoThe Suv39H1 methyltransferaseinhibitor chaetocin causes induction of integrated HIV-1 with-out producing a T cell responserdquo FEBS Letters vol 585 no 22pp 3549ndash3554 2011

[101] J FriedmanW-K Cho C K Chu et al ldquoEpigenetic silencing ofHIV-1 by the histone H3 Lysine 27 methyltransferase enhancerof Zeste 2rdquo Journal of Virology vol 85 no 17 pp 9078ndash90892011

[102] S Bouchat J-S Gatot K Kabeya et al ldquoHistone methyltrans-ferase inhibitors induce HIV-1 recovery in resting CD4+ T cellsfrom HIV-1-infected HAART-treated patientsrdquo AIDS vol 26no 12 pp 1473ndash1482 2012

[103] S K Choudhary N M Archin and D M Margolis ldquoHexam-ethylbisacetamide and disruption of human immunodeficiencyvirus type 1 latency in CD4+ T cellsrdquo Journal of InfectiousDiseases vol 197 no 8 pp 1162ndash1170 2008

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 201


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


Eliminate HIV-DNAby genome editing

Normal cellular DNA

Latent cell

Provirus

(a)

Normal receptor DNA

Modify receptor by genome editing

Modified receptorsprotect cells from

HIV infection

Uninfected cell

Modified receptor DNA

(b)

Figure 1 Two major strategies for HIV cure by using genome editing (a) Gene therapy strategies to eradicate HIV reservoirs Using ZFNTALENS or CRISPR to eliminate the HIV provirus in latent cells (b) Gene therapy strategies to prevent susceptible cells fromHIV infectionUsing gene editing to modify the receptor of susceptible cells and protect them from HIV infection

under development such as genome editing gene therapyand shock and kill [7 8]

Functional cure refers to the long-term control of HIVreplication which involves maintaining a normal CD4+ Tcell count and HIV replication below a detectable level [9]ldquoHIV controllersrdquo are considered to be those patients whoseHIV RNA is kept below the clinical baseline for a long periodwithout cART Studies on ldquoHIV controllersrdquo are expected toprovide important clues for the development of therapiesor strategies for functional HIV cure such as therapeuticvaccines and vector-mediated gene transfer therapy [10 11]Moreover the human genome has integrated a large numberof retrotransposon sequences over the course of evolutionandHIVmay coexist with humans if it is restricted From thisperspective the functional cure is as important as the steril-izing cureThis article will review the advancements in devel-oping strategies for both sterilizing and functionalHIV cures

2 Strategies for Sterilizing HIV Cure

21 Gene Therapy to Eradicate HIV Reservoirs Three majorgenome editing technologies have been used to eliminatethe HIV provirus including Zinc-finger nuclease (ZFN)technology the effects of transcription activator-like effector(TALENS) and clustered normal interspaced short palin-dromic repeat (CRISPR) and CRISPR-associated protein 9(CRISPR-Cas9) technologies [12ndash14] In contrast to normalcells HIV reservoir cells harbor a latent reservoir of HIVproviruses with the potential for replication Therefore ldquotar-geted eliminationrdquo of these cells will reduce their ability tocreate HIV viral offspring Accordingly some researchers usegenome editing technologies to mutate the target fragmentsof HIV proviruses in latent reservoir cells (Figure 1(a))

In 2011 Wayengera used ZFN technology to abrogatethe function of the pol gene However the modification ofthe coding sequence could not completely silence the HIV

provirus and the unmodified viral genes were still expressedunder the effect of long terminal repeat (LTR) [15] Qu etal then presented a possible alternative therapeutic approachby using specially designed zinc-finger nucleases (ZFNs)to target a sequence within the LTR to directly mediatea deletion of the HIV provirus from the HIV-integratedhumanT cell genome [16]The target sequencewas conservedacross all HIV clades making it suitable for a variety of HIVgenotypes Moreover they found that effective excision ofLTR could clear full-length HIV-1 proviral DNA In theirexperiment they observed that the frequency of excisionwas 459 in infected human cell lines after treatment [17]In 2014 the team used the LTR U3 region as a target ofZFN technology and successfully cleared about 30 of HIVproviruses from infected cells

One major challenge for both ZFN and TALENs is theexpense and labor involved A new genome editing toolCRISPRCas9 has recently entered the spotlight From 2013to 2014 two groups edited the integrated LTR on the cellgenome using the CRISPRCas9 system respectively andsucceeded in suppressing LTR-controlled gene transcription[18] The CRISPRCas9 system mutates not only HIV DNAin T cells but also some other HIV reservoir cells such asmicroglial cells and monocytes-macrophages FurthermoreCRISPRCas9 was verified to eliminate multiple HIV DNAcopies [18] Studies show the potential application of theCRISPRCas9 system in curing HIV infection By makingsite-specific DNA double-stranded breaks the CRISPRCas9system is also a unique antiviral defense system againstforeign plasmids and viruses A recent study reported that theCRISPRCas9 system interrupted the latently integrated viralgenome thereby forming a barrier against viral infectionsuggesting the CRISPRCas9 system as a new therapeuticstrategy [19]

Another study revealed that the CRISPRCas9 gene edit-ing technique could prevent the HIV virus from infecting




















Table1Re

agentsto

reactiv

ateH

IV-1fro

mlatency

Latencyreactiv

ating

reagents

Mechanism

Mod

elAd

vantageo

rdisa

dvantage

Reference

Valproicacid

(VPA

)HDAC

inhibitors

Clinical

Weakandno

nspecific

[87]

Butyric

acid

HDAC

inhibitors

Clinical

Approved

bytheF

DA

[88]

Vorin

ostat

(SAHAM

K0683)

HDAC

inhibitors

ACH-2U

1J-LAT

restin

gCD

4+cells

Approved

bytheF

DA

[3989]

Givinostat

HDAC

inhibitors

HIV-in

fected

celllin

esC

linical

Superio

rtoVPA

[90]

Pano

bino

stat

HDAC

inhibitors

ClinicalH

IV-in

fected

celllin

esLo

wer

toxicity

[3991]

Apicidin

Histon

emod

ificatio

nA106celllin

eSynergizew

ithtricho

statin

A[92]

Scrip

taid

Increasin

gthea

cetylatio

nlevelofh

iston

esH3

andH4

JurkatTcelllin

eLo

wer

toxicity

[93]

MC1

293

HDAC

inhibitor

Latencycelllin

esLo

wer

toxicitycomparedto

tricho

statin

A[47]

M344

HDAC

inhibitor

JurkatTcell

Anim

portantrolefor

histo

nemod

ificatio

ns[94]

As2O


nfactorsa

ndpathways

JurkatTcell

Synergisticallywith

prostratin

orVPA

[48]

OTX

015

Activ

atingNF-kapp

aBCell

EC50

valuelow

erthan

JQ1

[42]

Entin

ostat(MS275)

Inhibitin

gHDAC

1and

HDAC

3A7cell

Cytotoxicitylower

than

SAHA

[95]

Romidepsin

HDAC

inhibitor

ClinicalH

IV-in

fected

celllin

esSafe

[96]

JQ1

BETinhibitor

Celllines

Aversatile

chem

icalscaffoldbind

ingto

itsbrom

odom

ains

[40]

I-BE

T151

BETinhibitor

Tcells

from

cART

avire

micpatients

P-TE

Fb-releasin

gagents

[97]

MS417

BETinhibitor

J-Latcelllinesprim

aryCD

4+Tcells

ReleasingBR

D4fro

mthe51015840LT

R[97]

Interle

ukin

(IL)-2

Cytokinesa

ndchem

okines

HIV-1-infected

CD4+

Tcells

With

limitedsuccess

Interle

ukin

(IL)-7

Cytokinesa

ndchem

okines

Perip

heralblood

mon

onuclear

cells

Increasin

gviralprodu

ctionin

prod

uctiv

elyinfecting

cells

with

outd

isrup

tingthelatency

[9899]

Aza-C

dRDNMTinhibitors

Latentlyinfected

cells

AnFD

Aapproved

drug

[43]

Chaetocin

DNMTinhibitors

JurkatTcells

Increasin

gHIV

expressio

nwith


[100]

HMTi

3-deazaneplano

cinA

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

TargetingHKM

Tenhancer

ofZe

ste2

[101]

BIX-

01294

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

Synergisticactio

nthefi

rstH

MTinhibitoru

sedto

reactiv

ateH

IV-1in

vitro

[102]

Ingeno

lBPK

Cactiv

ators

J-LatA

1cell

Morep


1[44]

HMBA

P-TE

Fbactiv

ators

RestingCD

4+cells

Overcom

ingbarriersto

LTRexpressio

n[103]

Disu

lfiram

Unclassified

agents

CD4+

cells

Clinicaltrial

ZF-VP6

4Specificb

inding

tothe51015840-LTR

prom

oter

Latentlyinfected

cells

With

outalterin

gcellproliferatio

nor

cellcycle

progression

[45]

TALE

1-VP6

4Transcrip

tionactiv

ator-like

effector

C11and

A106cells

Nodistrib

utionof

cellproliferatio

nor

cellcycle

[46]

Dilazep

Nucleosidetranspo

rtinhibitor

JurkatTcell


ated

transcrip

tionwith

valproic

acid

[49]

















41205737

















Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




















Table1Re

agentsto

reactiv

ateH

IV-1fro

mlatency

Latencyreactiv

ating

reagents

Mechanism

Mod

elAd

vantageo

rdisa

dvantage

Reference

Valproicacid

(VPA

)HDAC

inhibitors

Clinical

Weakandno

nspecific

[87]

Butyric

acid

HDAC

inhibitors

Clinical

Approved

bytheF

DA

[88]

Vorin

ostat

(SAHAM

K0683)

HDAC

inhibitors

ACH-2U

1J-LAT

restin

gCD

4+cells

Approved

bytheF

DA

[3989]

Givinostat

HDAC

inhibitors

HIV-in

fected

celllin

esC

linical

Superio

rtoVPA

[90]

Pano

bino

stat

HDAC

inhibitors

ClinicalH

IV-in

fected

celllin

esLo

wer

toxicity

[3991]

Apicidin

Histon

emod

ificatio

nA106celllin

eSynergizew

ithtricho

statin

A[92]

Scrip

taid

Increasin

gthea

cetylatio

nlevelofh

iston

esH3

andH4

JurkatTcelllin

eLo

wer

toxicity

[93]

MC1

293

HDAC

inhibitor

Latencycelllin

esLo

wer

toxicitycomparedto

tricho

statin

A[47]

M344

HDAC

inhibitor

JurkatTcell

Anim

portantrolefor

histo

nemod

ificatio

ns[94]

As2O


nfactorsa

ndpathways

JurkatTcell

Synergisticallywith

prostratin

orVPA

[48]

OTX

015

Activ

atingNF-kapp

aBCell

EC50

valuelow

erthan

JQ1

[42]

Entin

ostat(MS275)

Inhibitin

gHDAC

1and

HDAC

3A7cell

Cytotoxicitylower

than

SAHA

[95]

Romidepsin

HDAC

inhibitor

ClinicalH

IV-in

fected

celllin

esSafe

[96]

JQ1

BETinhibitor

Celllines

Aversatile

chem

icalscaffoldbind

ingto

itsbrom

odom

ains

[40]

I-BE

T151

BETinhibitor

Tcells

from

cART

avire

micpatients

P-TE

Fb-releasin

gagents

[97]

MS417

BETinhibitor

J-Latcelllinesprim

aryCD

4+Tcells

ReleasingBR

D4fro

mthe51015840LT

R[97]

Interle

ukin

(IL)-2

Cytokinesa

ndchem

okines

HIV-1-infected

CD4+

Tcells

With

limitedsuccess

Interle

ukin

(IL)-7

Cytokinesa

ndchem

okines

Perip

heralblood

mon

onuclear

cells

Increasin

gviralprodu

ctionin

prod

uctiv

elyinfecting

cells

with

outd

isrup

tingthelatency

[9899]

Aza-C

dRDNMTinhibitors

Latentlyinfected

cells

AnFD

Aapproved

drug

[43]

Chaetocin

DNMTinhibitors

JurkatTcells

Increasin

gHIV

expressio

nwith


[100]

HMTi

3-deazaneplano

cinA

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

TargetingHKM

Tenhancer

ofZe

ste2

[101]

BIX-

01294

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

Synergisticactio

nthefi

rstH

MTinhibitoru

sedto

reactiv

ateH

IV-1in

vitro

[102]

Ingeno

lBPK

Cactiv

ators

J-LatA

1cell

Morep


1[44]

HMBA

P-TE

Fbactiv

ators

RestingCD

4+cells

Overcom

ingbarriersto

LTRexpressio

n[103]

Disu

lfiram

Unclassified

agents

CD4+

cells

Clinicaltrial

ZF-VP6

4Specificb

inding

tothe51015840-LTR

prom

oter

Latentlyinfected

cells

With

outalterin

gcellproliferatio

nor

cellcycle

progression

[45]

TALE

1-VP6

4Transcrip

tionactiv

ator-like

effector

C11and

A106cells

Nodistrib

utionof

cellproliferatio

nor

cellcycle

[46]

Dilazep

Nucleosidetranspo

rtinhibitor

JurkatTcell


ated

transcrip

tionwith

valproic

acid

[49]

















41205737

















Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology













Table1Re

agentsto

reactiv

ateH

IV-1fro

mlatency

Latencyreactiv

ating

reagents

Mechanism

Mod

elAd

vantageo

rdisa

dvantage

Reference

Valproicacid

(VPA

)HDAC

inhibitors

Clinical

Weakandno

nspecific

[87]

Butyric

acid

HDAC

inhibitors

Clinical

Approved

bytheF

DA

[88]

Vorin

ostat

(SAHAM

K0683)

HDAC

inhibitors

ACH-2U

1J-LAT

restin

gCD

4+cells

Approved

bytheF

DA

[3989]

Givinostat

HDAC

inhibitors

HIV-in

fected

celllin

esC

linical

Superio

rtoVPA

[90]

Pano

bino

stat

HDAC

inhibitors

ClinicalH

IV-in

fected

celllin

esLo

wer

toxicity

[3991]

Apicidin

Histon

emod

ificatio

nA106celllin

eSynergizew

ithtricho

statin

A[92]

Scrip

taid

Increasin

gthea

cetylatio

nlevelofh

iston

esH3

andH4

JurkatTcelllin

eLo

wer

toxicity

[93]

MC1

293

HDAC

inhibitor

Latencycelllin

esLo

wer

toxicitycomparedto

tricho

statin

A[47]

M344

HDAC

inhibitor

JurkatTcell

Anim

portantrolefor

histo

nemod

ificatio

ns[94]

As2O


nfactorsa

ndpathways

JurkatTcell

Synergisticallywith

prostratin

orVPA

[48]

OTX

015

Activ

atingNF-kapp

aBCell

EC50

valuelow

erthan

JQ1

[42]

Entin

ostat(MS275)

Inhibitin

gHDAC

1and

HDAC

3A7cell

Cytotoxicitylower

than

SAHA

[95]

Romidepsin

HDAC

inhibitor

ClinicalH

IV-in

fected

celllin

esSafe

[96]

JQ1

BETinhibitor

Celllines

Aversatile

chem

icalscaffoldbind

ingto

itsbrom

odom

ains

[40]

I-BE

T151

BETinhibitor

Tcells

from

cART

avire

micpatients

P-TE

Fb-releasin

gagents

[97]

MS417

BETinhibitor

J-Latcelllinesprim

aryCD

4+Tcells

ReleasingBR

D4fro

mthe51015840LT

R[97]

Interle

ukin

(IL)-2

Cytokinesa

ndchem

okines

HIV-1-infected

CD4+

Tcells

With

limitedsuccess

Interle

ukin

(IL)-7

Cytokinesa

ndchem

okines

Perip

heralblood

mon

onuclear

cells

Increasin

gviralprodu

ctionin

prod

uctiv

elyinfecting

cells

with

outd

isrup

tingthelatency

[9899]

Aza-C

dRDNMTinhibitors

Latentlyinfected

cells

AnFD

Aapproved

drug

[43]

Chaetocin

DNMTinhibitors

JurkatTcells

Increasin

gHIV

expressio

nwith


[100]

HMTi

3-deazaneplano

cinA

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

TargetingHKM

Tenhancer

ofZe

ste2

[101]

BIX-

01294

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

Synergisticactio

nthefi

rstH

MTinhibitoru

sedto

reactiv

ateH

IV-1in

vitro

[102]

Ingeno

lBPK

Cactiv

ators

J-LatA

1cell

Morep


1[44]

HMBA

P-TE

Fbactiv

ators

RestingCD

4+cells

Overcom

ingbarriersto

LTRexpressio

n[103]

Disu

lfiram

Unclassified

agents

CD4+

cells

Clinicaltrial

ZF-VP6

4Specificb

inding

tothe51015840-LTR

prom

oter

Latentlyinfected

cells

With

outalterin

gcellproliferatio

nor

cellcycle

progression

[45]

TALE

1-VP6

4Transcrip

tionactiv

ator-like

effector

C11and

A106cells

Nodistrib

utionof

cellproliferatio

nor

cellcycle

[46]

Dilazep

Nucleosidetranspo

rtinhibitor

JurkatTcell


ated

transcrip

tionwith

valproic

acid

[49]

















41205737

















Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


Table1Re

agentsto

reactiv

ateH

IV-1fro

mlatency

Latencyreactiv

ating

reagents

Mechanism

Mod

elAd

vantageo

rdisa

dvantage

Reference

Valproicacid

(VPA

)HDAC

inhibitors

Clinical

Weakandno

nspecific

[87]

Butyric

acid

HDAC

inhibitors

Clinical

Approved

bytheF

DA

[88]

Vorin

ostat

(SAHAM

K0683)

HDAC

inhibitors

ACH-2U

1J-LAT

restin

gCD

4+cells

Approved

bytheF

DA

[3989]

Givinostat

HDAC

inhibitors

HIV-in

fected

celllin

esC

linical

Superio

rtoVPA

[90]

Pano

bino

stat

HDAC

inhibitors

ClinicalH

IV-in

fected

celllin

esLo

wer

toxicity

[3991]

Apicidin

Histon

emod

ificatio

nA106celllin

eSynergizew

ithtricho

statin

A[92]

Scrip

taid

Increasin

gthea

cetylatio

nlevelofh

iston

esH3

andH4

JurkatTcelllin

eLo

wer

toxicity

[93]

MC1

293

HDAC

inhibitor

Latencycelllin

esLo

wer

toxicitycomparedto

tricho

statin

A[47]

M344

HDAC

inhibitor

JurkatTcell

Anim

portantrolefor

histo

nemod

ificatio

ns[94]

As2O


nfactorsa

ndpathways

JurkatTcell

Synergisticallywith

prostratin

orVPA

[48]

OTX

015

Activ

atingNF-kapp

aBCell

EC50

valuelow

erthan

JQ1

[42]

Entin

ostat(MS275)

Inhibitin

gHDAC

1and

HDAC

3A7cell

Cytotoxicitylower

than

SAHA

[95]

Romidepsin

HDAC

inhibitor

ClinicalH

IV-in

fected

celllin

esSafe

[96]

JQ1

BETinhibitor

Celllines

Aversatile

chem

icalscaffoldbind

ingto

itsbrom

odom

ains

[40]

I-BE

T151

BETinhibitor

Tcells

from

cART

avire

micpatients

P-TE

Fb-releasin

gagents

[97]

MS417

BETinhibitor

J-Latcelllinesprim

aryCD

4+Tcells

ReleasingBR

D4fro

mthe51015840LT

R[97]

Interle

ukin

(IL)-2

Cytokinesa

ndchem

okines

HIV-1-infected

CD4+

Tcells

With

limitedsuccess

Interle

ukin

(IL)-7

Cytokinesa

ndchem

okines

Perip

heralblood

mon

onuclear

cells

Increasin

gviralprodu

ctionin

prod

uctiv

elyinfecting

cells

with

outd

isrup

tingthelatency

[9899]

Aza-C

dRDNMTinhibitors

Latentlyinfected

cells

AnFD

Aapproved

drug

[43]

Chaetocin

DNMTinhibitors

JurkatTcells

Increasin

gHIV

expressio

nwith


[100]

HMTi

3-deazaneplano

cinA

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

TargetingHKM

Tenhancer

ofZe

ste2

[101]

BIX-

01294

DNMTinhibitors

RestingCD

4+Tcells

orJurkatTcells

Synergisticactio

nthefi

rstH

MTinhibitoru

sedto

reactiv

ateH

IV-1in

vitro

[102]

Ingeno

lBPK

Cactiv

ators

J-LatA

1cell

Morep


1[44]

HMBA

P-TE

Fbactiv

ators

RestingCD

4+cells

Overcom

ingbarriersto

LTRexpressio

n[103]

Disu

lfiram

Unclassified

agents

CD4+

cells

Clinicaltrial

ZF-VP6

4Specificb

inding

tothe51015840-LTR

prom

oter

Latentlyinfected

cells

With

outalterin

gcellproliferatio

nor

cellcycle

progression

[45]

TALE

1-VP6

4Transcrip

tionactiv

ator-like

effector

C11and

A106cells

Nodistrib

utionof

cellproliferatio

nor

cellcycle

[46]

Dilazep

Nucleosidetranspo

rtinhibitor

JurkatTcell


ated

transcrip

tionwith

valproic

acid

[49]

















41205737

















Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

















41205737

















Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology












Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Naive cell



ldquoKillrdquo

Protectnaive cells


Therapeutic vaccine


Infection

ADCC

CTL

New drugs







4 Conclusion








Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology







Acknowledgments


References


















































































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology























































































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology






















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




















Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

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Advancements in Developing Strategies for Sterilizing and …downloads.hindawi.com/journals/bmri/2017/6096134.pdf · 2019. 7. 30. · by using specially designed zinc-finger nucleases