A  therapeu*c  nanopar*cle  vaccine  against  Trypanosoma  cruzi  in  a  mouse  model  of  Chagas  disease    

Meagan  A.  Barry1,2,3,  Qian  Wang4,  Kathryn  M.  Jones1,4,  Michael  J.  Heffernan4,  Eric  Dumonteil5,  &  Peter  J.  Hotez1,3,4    1Na*onal  School  of  Tropical  Medicine,  2Medical  Scien*st  Training  Program,  3Program  in  Transla*onal  Biology  and  Molecular  Medicine,  4Department  of  Pediatrics,  Baylor  College  of  Medicine,  Houston,  TX,  USA.    

5Laboratory  of  Parasitology,  Universidad  Autonoma  de  Yucatan,  Merida,  Mexico.  

VACCINE  FORMULATION  

Chagas  disease  is  a  neglected  tropical  disease  of  great   importance  in  the  Americas,  with  7-­‐8  million  people  infected.  The  causa*ve  agent  is  Trypanosoma  cruzi  (T.  cruzi),  and   results   in   an   acute   febrile   illness   that   progresses   to   chronic   chagasic  cardiomyopathy  in  30%  of  pa*ents.  Current  pharmacological  treatments  are  plagued  by  significant  side  effects,  poor  efficacy,  and  are  contraindicated  in  pregnancy.  There  is   an  urgent   need   for   new   treatment  modali*es.  A   therapeu*c   vaccine   for   Chagas  disease  has  poten*al  advantages  that  include  cost  savings,  reduced  adverse  effects,  and  the  poten*al  to  be  used  as  a  replacement  for  current  therapies  or  when  paired  with  chemotherapy.  Prior  work  in  mice  has  iden*fied  an  efficacious  T.  cruzi  an*gen  (Tc24).      We  hypothesize   that   the   recombinant   Tc24,  when  delivered   in   a  poly(lac<c-­‐co-­‐glycolic   acid)   (PLGA)   nanopar<cle   delivery   system   with   CpG   mo<f-­‐containing  oligodeoxynucleo<des   (ODN)  as   an   immunomodulatory   adjuvant,  will  induce  a  TH1-­‐mediated  CD8+  T  cell  immune  response,  ul<mately  resul<ng  in  decreased  parasitemia,  increased  survival,  and  reduced  cardiac  pathology  in  our  murine  model.  

ACKNOWLEDGEMENTS  

Our   nanopar*cle   vaccine,   comprised   of   Tc24   and   CpG  ODN   encapsulated   in   PLGA  nanopar*cles,   produced   a   robust   TH1-­‐baised   immune   response.   When   tested   for  therapeu*c   efficacy   in   T.   cruzi   infected   BALB/c  mice,   improved   survival   was   seen.  Addi*onally,   there   was   a   significant   reduc*on   in   the   number   of   parasites   in   the  cardiac   *ssue,   sugges*ng   protec*on   from   parasite-­‐driven   cardiac   damage.   These  data   demonstrate   the   immunogenicity   and   efficacy   of   a   Tc24/CpG   ODN  nanopar<cle  vaccine  and  are  convincing  evidence  for  a  poten<al  new  therapeu<c  vaccine  against  Chagas  disease.    

We  thank  Coreen  M.  Beaumier  and  Brian  P.  Keegen  for  their  invaluable  help.  Meagan  Barry,  e-­‐mail:  mabarry@bcm.edu  

Baylor  College  of  Medicine,  1  Baylor  Plaza,  Houston,  TX  77030  

MEDICAL SCIENTIST TRAINING PROGRAM

M.D./PH.D.

OO

O

Ox y

•  Flagellar  Ca2+  binding  protein    

•  Expressed  in  all  developmental  stages    

•  Highly  immunogenic  

An*gen:  Tc24  

Delivery  System:  PLGA  nanopar*cles  

•  Biocompa*ble    •  Biodegradable    •  FDA  approved  as  an  

excipient    

Study  Groups  PLGA[Tc24]  

Alum  with  Tc24  

Soluble  Tc24  

0 5 10 15 20 250

50

100

150

200

Days post-injection

Perc

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of in

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flu

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cenc

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tens

ity PLGA[Tc24]Alum with Tc24Soluble Tc24

AF660-­‐labeled  Tc24  

In  vivo  Imaging  

Inject  SQ  

BALB/c  

IMMUNOGENICITY    

KINETICS  OF  ANTIGEN  DISPERSAL  

500  T.  cruzi    H1  trypomas*gotes  

Study  Groups  

PLGA[Tc24]  +PLGA[CpG]  

Unvaccinated  

PLGA[Tc24]  

PLGA[CpG]  

0 10 20 30 40 500

50

100

Perc

ent s

urvi

val

Days

PLGA[Tc24] + PLGA[CpG] UnvaccinatedPLGA[Tc24]PLGA[CpG]

d0   d24  d7   d14  d1   d3   d5  d2   d10   d19  

FINDINGS:  The  PLGA  nanopar*cle  serves  as  a  depot,  similar  to  alum,  allowing  a  prolonged  release  of  protein  over  *me    

Soluble  Tc24  

Tc24  +  Alum  

PLGA

[Tc24]  

10min   4hr   1d   10d  

Study  Groups  

Group  Name   A   B   C   D   E   F  

Nanopar*cles  (mg)   2   1   0.5   0.25   0.13   -­‐  

Tc24  (ug)   14.4   7.2   3.6   1.8   0.9   -­‐  

CpG  (ug)   7.6   3.8   1.9   0.95   0.48   -­‐  

Immunize  SQ  

BALB/c  d0   d56  d28  

FINDINGS:  A  sta*s*cally  significant  TH1-­‐biased  immune  response  with  increased  dose  

Representa*ve  Mice   Dispersal  of  Fluorescently  Labeled  Tc24  Over  Time  

Tc24-­‐specific  IFN-­‐γ  Producing  Cells     Tc24-­‐specific  IgG2a  An*body  Titers  

Infect  IP  

Immunize  SQ  

d0   d50  d14  d7  

THERAPEUTIC  EFFICACY  

Survival  Through  Acute  Phase  of  Disease   Parasite  Burden  In  Cardiac  Tissue  

Cardiac  Tissue

:  Vaccinated  

INTRODUCTION  

CONCLUSIONS  

FINDINGS:  The  vaccine  results  in  improved  survival  and  significant  reduc*on  in  parasites  in  the  cardiac  *ssue  

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PLGA[Tc2

4] + P

LGA[CpG]

Unvacc

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PLGA[Tc2

4]

PLGA[CpG]

0

100

200

300p < 0.01

Key

Alive at d50 post-infectionDead at d50 post-infection1.90

1.95

2.00

2.05

2.10

Alive at d50 post-infectionDead at d50 post-infection

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Unvacc

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PLGA[Tc2

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PLGA[CpG]

0

100

200

300p < 0.01

Cardiac  Tissue

:  Unvaccinated  

•  Short,  synthe*c  DNA  that  contains  CpG  mo*fs  

•  Toll  like  receptor  (TLR)  9  agonist  

Adjuvant:  CpG  ODN  

Poly(lac*c-­‐co-­‐glycolic  acid)  

Characteriza*on  of  Nanopar*cles  

•  Morphology  &  size  •  Size  distribu*on    •  Loading  efficacy  

A   B   C   D   E   F  

Study  Groups  

A   B   C   D   E   F  

Study  Groups  

BALB/c