Trends in vaccinology

Mathieu Peeters, MD

Joint Conference of European Human Pharmacological Societies and Joint Conference of European Human Pharmacological Societies and 20th Anniversary of AGAHMarch 31 - April 01, 2011 | Berlin, Germany

Edward JENNER: 1796

Observed protection from Smallpox in milkmaids

Edward JENNER: 1796

Observed protection from Smallpox in milkmaids exposed to cowpox – injected an 8 year old boy with pus from a milkmaid’s cowpox lesion

Protection against human smallpox

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Many new vaccines since Jenner

rotavirus

Many new vaccines since Jenner

conjug pneumococcal

cervical cancer

HA/HB

hepatitis AHib

Pa comboDTP

rubellameningococcus

pneumococcushepatitis B

Hib

OPV (polio Sabin)measles

mumpsrubella

pertussisinfluenza

yellow fever

IPV (polio Salk)

rabies diphtheriatuberculosis

tetanuscholera

pertussis

rabies diphtheria

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What have vaccines achieved so far?What have vaccines achieved so far?

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Attenuated & Inactivatedvaccines historyvaccines history

Animal virus (vaccinia)18th Century

Physical attenuation(Rabies, Anthrax) Killed whole organisms

19th Century

Passage in animals,

Killed whole organisms(thypoid, cholera,

Whole-cell pertussis, IPV, hepatitis)20th Century

Passage in animals, eggs, in vitro

(Yellow fever, BCG)

Toxoids(Diptheria, Tetanus)

Extracts(Flu, Anthrax, Rabies)

Passage in cell culture

Polysaccharides (Pneumo, Typhoid)

Proteins(Acellular Pertussis, Hep B)Passage in cell culture

in vitro(Measles, OPV, Varicella, Mumps Rubella, Live flu) Conj. Polysaccharides

(pneumo, Hib, meningo)Peptides

(pneumo, Hib, meningo)

Adapted from : Plotkin et al. Clinical and vaccine immunology 2009, vol 16, 1709-19.

Live Attenuated Vaccines

Developing an attenuated strainDeveloping an attenuated strain

Live Attenuated Vaccines

Developing an attenuated strainDeveloping an attenuated strain

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Live attenuated vaccinesLive attenuated vaccines

� Extremely effective

� Best way to stimulate all the components of immunity that infection with the pathogenic organism does,

� Some pathogens considered too risky even in attenuated form

� Immune responses elicited by wild-type infection are not necessarily effective for � Immune responses elicited by wild-type infection are not necessarily effective for clearing a pathogen after an infection.

� Risk of reversion to virulent form

Inactivated VaccinesInactivated Vaccines

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Inactivated VaccinesInactivated Vaccines

�Generally used for pathogens for which a humoral immune �Generally used for pathogens for which a humoral immune response is considered the primary protective immune response

� Inadequate for inducing the appropriate forms of cellular immunity needed for certain diseases.

Subunit Vaccines

Recombinant vaccines e.g. Hepatitis B Surface AntigenRecombinant vaccines e.g. Hepatitis B Surface Antigen

Subunit Vaccines

Recombinant vaccines e.g. Hepatitis B Surface AntigenRecombinant vaccines e.g. Hepatitis B Surface Antigen

Subunit Vaccines

Recombinant subunit vaccinesRecombinant subunit vaccines

Subunit Vaccines

Recombinant subunit vaccinesRecombinant subunit vaccines

Subunit VaccinesSubunit Vaccines

�Free of infectious particles (↔ plasma-derived vaccines)�Free of infectious particles (↔ plasma-derived vaccines)

�Once a suitable Master Working Cell Bank has been established, the �Once a suitable Master Working Cell Bank has been established, the antigens can be produced efficiently, economically and on a large scale.

�The use of highly purified antigens has decreased the risk of vaccine �

toxicity but, as a consequence, the immunogenicity of some of these vaccine antigens is suboptimal.

Vaccinology : an evolving science

�Vaccine development has historically progressed by trial and error

�Shift towards knowledge based R&D

–Pathogen–Pathogen

–Immune system

–Immune response–Immune response

–Target population

�Modern approaches to develop new or improved vaccines

New technologies availableNew technologies available

�New adjuvants�New adjuvants

�Target antigen�Target antigen–Conjugates (carrier + peptide, carrier + PS, ...)–Gene based vaccines–Gene based vaccines

–DNA vaccines–Live vectored (virus/bact) vaccines

–Virus like particles

�� Immunisation routes–Intradermal

–Mucosal (oral, nasal, …) ...–Mucosal (oral, nasal, …) ...

Vaccine adjuvantsVaccine adjuvants

� Latin “adjuvare”: to help� Latin “adjuvare”: to help

�� An adjuvant can be an immunostimulant and/or a vaccine delivery system–– Vaccine delivery system : “transports” the antigen

– Immunostimulant : compound that acts directly or indirectly on the immunocompetent cells to increase the immune response to a given immunocompetent cells to increase the immune response to a given antigen

� It is designed to increase the specific immune response (intensity, quality and breadth)

Gaston Ramon : Adjuvant Innovation

In 1925, Ramon was first to recognize that a variety of substances could increase a variety of substances could increase antigen-specific antibody production

when added to diphtheria and tetanus toxoids prior to vaccination.toxoids prior to vaccination.

Aluminum salt is the most Aluminum salt is the most widely used adjuvant

Why Do We Need Better Adjuvants?

�To increase the magnitude of the immune response

�To bypass weakened immunity–Immunosenescence

�To increase production capacity by reducing antigen content/dose

�To increase the magnitude of the immune response

�To induce long-term protection–Long-term persistence of protection

–Immunosenescence–Immunosuppression

reducing antigen content/dose

–Long-term persistence of protection –Immunological memory

Vaccine with Adjuvant System

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Why Do We Need Better Adjuvants?

�Adjuvant’s activate different arms of the immune system and �Adjuvant’s activate different arms of the immune system and enhance the immune response

humoral cellular immunityhumoral cellular immunity

Extracellular targets Infected cellsExtracellular targets Infected cells

�However, need to keep an appropriate balance between immunogenicity and reactogenicityimmunogenicity and reactogenicity

Gene-Based VaccinesGene-Based Vaccines

�Recombinant plasmid DNA�Recombinant plasmid DNA–Mammalian expression vectors - express antigen gene(s) in transfected

cells after intramuscular or intradermal delivery

�Recombinant live virus vectors–Attenuated virus vector (e.g. Adenovirus) undergoes transient replication –Attenuated virus vector (e.g. Adenovirus) undergoes transient replication

after injection - expression of antigen gene(s)

Direct transfection of APCDNA vaccines

apoptosis, secreted,

Transfection of

secreted, VLP…

Transfection of muscle cells or keratynocytes

Adapted from: http://www.vical.com

Key advantages of DNA vaccinesKey advantages of DNA vaccines

� Induce both humoral and cellular immune responses (incl. CTL) similar to live attenuated platforms attenuated platforms

� Safe

– Unable to revert into virulent forms, unlike live vaccines– Unable to revert into virulent forms, unlike live vaccines

– No significant adverse events in clinical trials

� Stability

– Storage at room temperature

– No cold chain requirement

– Long shelf-life– Long shelf-life

– Easy distributable in developing countries

� Ease of manufacturing

– Rapid production and formulation

– Relatively inexpensive

– Large scale production– Large scale production

Potential concerns

� Efficacy� Efficacy

–First-generation DNA plasmids elicited low levels of T and B cell memory

� Safety

–DNA integration–DNA integration

–Autoimmunity against patient DNA

Viral vectorViral vector

Livevector

proteinLivevector

protein

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CD8

CD4 B

CD8

CD4 BCD8 CD4 B

CTL T helperAPC

CD8 CD4 B

CTL T helperAPC

CTL T helperCTL T helper

Potential advantages of virus derived vectorsPotential advantages of virus derived vectors

� High-level production of protein antigens directly within the cells of the � High-level production of protein antigens directly within the cells of the immunized host

� Possibility of efficient delivery of antigen directly to the components of the � Possibility of efficient delivery of antigen directly to the components of the immune system

� Potential adjuvant effects of the viral delivery system

� Potential to be administered via different routes; also intradermal, intranasal, � Potential to be administered via different routes; also intradermal, intranasal, intra-rectal, intra-vaginal (and induce mucosal immune response)

Potential issuePotential issue

� Pre-existing immunity against the vector

Virus Like Particles (VLP)Virus Like Particles (VLP)

� Multiprotein structure that mimic the oganization and conformation of � Multiprotein structure that mimic the oganization and conformation of authentic native viruses but lack the viral genome

VirusVLP

Virus Like Particles (VLP)Virus Like Particles (VLP)

Insertion of gene in virus

Initial stock of recombinant

virusvirus

Inoculation in Inoculation in fresh cellculture

Virus enters cell. ItsVirus enters cell. Itsgenome moves intothe nucleus

Production of Production of proteins, assemblyinto pentamers

Cells collectedand disrupted

Highly purified VLP

Potential advantages of VLPPotential advantages of VLP

� No requirement for inactivation or attenuation� No requirement for inactivation or attenuation

–Epitopes might be altered by inactivation

� Conformational epitopes more similar to the native virus� Conformational epitopes more similar to the native virus

–Improved immune system response

� Main challenge = bioengineering issues� Main challenge = bioengineering issues

Alternative Delivery

Samir Mitragotri

NATURE REVIEWS IMMUNOLOGYVOLUME 5 DECEMBER 2005

Cutaneous immunizationCutaneous immunization

Samir MitragotriNATURE REVIEWS IMMUNOLOGYVOLUME 5 DECEMBER 2005

Advantages and limitations of needle-free deliveryAdvantages and limitations of needle-free delivery

Samir MitragotriNATURE REVIEWS IMMUNOLOGYVOLUME 5 DECEMBER 2005

…and industrial feasibility, patient acceptance …

THERAPEUTIC VACCINESTHERAPEUTIC VACCINES

�Cancer: �Cancer:

–contain novel cellular antigens, vaccine with proteins/peptides expressed by cancerexpressed by cancer

�Tolerization to auto-antigens in auto-immune diseases (MS, diabetes)

�Drug addiction (cocaine, nicotine): Ab that removes drugs from body�Drug addiction (cocaine, nicotine): Ab that removes drugs from body

�Alzheimer: immunization against amyloid

�Contraception: immunization against hormones�Contraception: immunization against hormones

Advances in Molecular biology Discovery oftumor Associated Antigenstumor Associated Antigens

�Cancer cells have altered gene expression profile different from normal �Cancer cells have altered gene expression profile different from normal cells: tumor associated antigens exist !!

�Differences between normal and tumor cells are potential targets for �Differences between normal and tumor cells are potential targets for immunotherapy

Antigen specific cancer immunotherapyAntigen specific cancer immunotherapy

Antibody production

Helper T-Cells

Naive CD8+ Lymphocyte

Cytolytic T-cellsNaive CD4+

LymphocyteLymphocyte

Tumor (C)Draining Lymph Node (B)injection site (A) Tumor (C)Draining Lymph Node (B)injection site (A)

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Conclusions

� Many opportunities

– access to new technologies through research and collaborations– access to new technologies through research and collaborations

– progress in fundamental immunology

– development of support technologies – development of support technologies

– better understanding of molecules (eg. physical chemistry)

– better understanding of biological systems (eg. omics)– better understanding of biological systems (eg. omics)

�� Pave the way towards new vaccine targets in infectious disease, immunotherapy, allergy, life-style, autoimmunity, ...

Conclusions Conclusions

� …. but also many challenges� …. but also many challenges– Predicting immune correlates of protection

– Improving T cell responses – Improving T cell responses

–Delivery systems, vectors, adjuvants, combination “prime-boost” strategiesboost” strategies

– Vaccines for the elderly

– Vaccines for the very young– Vaccines for the very young

– Cold chain and supply …