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Strategies for Vaccine Design

Strategies for Vaccine Design. Jay A. Berzofsky, M.D., Ph.D. Chief, Vaccine Branch, CCR, NCI. Preparing for Biothreats: Emerging and Re-emerging Infectious Diseases Boston University, Boston, MA, December 14, 2005. Rationale.

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Strategies for Vaccine Design

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  1. Strategies for Vaccine Design Jay A. Berzofsky, M.D., Ph.D. Chief, Vaccine Branch, CCR, NCI Preparing for Biothreats: Emerging and Re-emerging Infectious Diseases Boston University, Boston, MA, December 14, 2005

  2. Rationale • For viruses causing acute, self-limited infections, the most widely used strategy is to mimic the natural infection with an attenuated, inactivated, or subunit vaccine. • However, for viruses causing chronic infection, such as HIV or hepatitis C virus, or for cancer, the natural disease does not induce sufficient immunity to eradicate the infection or tumor. • A vaccine must elicit better immunity than the virus or cancer itself.

  3. Vaccine strategies to elicit cytotoxic T lymphocytes (CTL) need to focus on several properties: • Quantity of CTL. • Avidity of CTL ==> Greater efficacy at clearing virus or killing tumor • Longevity or memory of CTL. Strategies based on use of: Cytokines Costimulatory molecules Inhibitors of negative regulation Enhanced epitopes--sequences modified to increase binding to MHC molecules Targeting of vaccines to mucosal sites

  4. Peptide Fragments of Viral Proteins Bind Specifically in the Grooveof Major Histocompatibility Molecules such as HLA-A, B, C Sendai Virus Peptide Bound to H-2Kb From DH Fremont, M. Matsumura, EA Stura, PA Peterson, & IA Wilson. Science 257: 919-926, 1992 Strategy: Epitope Enhancement by Sequence Modification to Increase Peptide Affinity for the MHC Molecule

  5. IL-2 & IL-15: SHARED FUNCTIONS IN IMMUNE SYSTEM (ADOPTIVE IMMUNITY) Macrophage DC Epithelium BM Stroma Activated CD4 IL-2 IL-15 B CTL CD4 CD8 Proliferation Effector Function Proliferation IgA

  6. IL-2 & IL-15: DISTINCT FUNCTIONS IL-15 IL-2 Activated T cells Memory T cells Mast cell proliferation Antigen- Induced Cell Death NK cell development Maintenance

  7. Boosted Unimmunized 5 vPE16 vPE16/VV-IL-15 vPE16/VV-IL-2 4 % of IFN-gamma producing CD8+ T cells 3 2 1 0 6 months 8 months 3 wks 2 months 14 months 4 months Time after Booster Immunization IL-15 expression by a vaccine vector induced longer-lived memory CD8+ CTL: IFN-gamma-producing cells Explained by 1. Higher IL-15Ra expression 2. Greater homeostatic proliferation Oh et al., PNAS 2003

  8. Immunization with antigen + IL-15 induces higher avidity memory CD8+ CTL vPE16 120 vPE16/IL-15 100 80 % of maximum lysis 60 40 20 0 1 10 0.1 0.01 0.001 1E-05 0.0001 Control Target cells pulsed with [P18-I10], mM 2 months after immunization Oh et al., PNAS 2004

  9. High Avidity CTL Clear Virus Infection in SCID Mice More Effectively Than Low Avidity CTL Alexander-Miller et al., PNAS 1996

  10. Improved viral clearance by high avidity CTL Low avidity CTL High avidity CTL Derby et al., J. Immunol. 2001

  11. Role of IL-15 and costimulation in CTL Avidity Maturation APC IL-15 in vaccine Signal 1 Signal 2 CD8 T cells Strong Signal 2 Selection Induction Increased survival and Homeostatic proliferation Increased CD8 ab Higher functional avidity Induction at individual cell level Selection at population level High Avidity CTL Increased IL-15Ra IL-15 Oh et al. J. Immunol. , 2003; and Oh et al. PNAS, 2004

  12. IL-15 with vaccine CD4+ Helper T cell CD40L IL-15 IL-12 TCR B7 costimulator CD4+ T-cell Help for CD8+ CTL Mediated Through Activation of Dendritic Cell + CD8 Cytotoxic T cell TCR CD28 MHC Class I CD40 MHC Class II Dendritic Cell

  13. Immunotherapy of cancer or HIV is still not an established modality of treatment. WHY? Immune suppression by tumor or HIV Immune evasion Immune suppression by immune cells M2 macrophages or tumor associated macrophages (TAM) Myeloid suppressor cells (MSC) CD4+CD25+ T regulatory cells (Treg) Natural Killer (NK) T cells

  14. Ts Th3 Tr1 NKT TReg Regulatory/Suppressor T cells CD4 Contact inhibition MHC class II-restricted CD25 (IL-2Ra) TGF-bMHC class II-restricted abTCR IL-10 (& TGF-b) MHC class II-restricted CD4 IFN-g, IL-4, IL-13CD1d-restricted NK1.1 CD8 ? Qa-1-restricted abTCR

  15. TGF- IL-13 NKT cells and IL-13 suppress CTL tumor immune surveillance though the IL-4R-STAT6 pathway to induce TGF-b production by CD11b+Gr-1+ cells CTL Tumor cells tumor lysis suppression of CTL activation APC glycolipid CD1d CD1d-restricted CD4+NKT IL-4Ra IL-13Ra1 STAT6 CD11b+ Gr1+ Terabe et al., Nat Immunol, 2000., Terabe et al., J Exp Med, 2003.

  16. CD1- KO Wild-type BALB/c anti-CD8 anti-CD4 anti-CD4,CD8 Absence of CD1d-restricted NKT cells unmasks CD8+ Cell- dependent immunosurveillance and not improved by deletion of CD4+ Cells >250 200 150 Number of Nodules 100 Lungs stained with India ink for contrast 50 0 Untreated RatIgG BALB/c CD1-KO Park et al., Internat. J. Cancer, 2005.

  17. Prevention of lung tumor metastases of CT26 by anti-TGF-b antibody Number of nodules/lung control mAb(13C4) control anti-TGF-b (1D11) Terabe et al., J Exp Med , 2003

  18. Conclusions: CT26 model CTL Tumor cells tumor lysis suppression of CTL activation APC TGF- IL-13 CD1d glycolipid CD1d-restricted CD4+NKT IL-4Ra IL-13Ra1 STAT6 CD11b+ Gr1+ • Even in a non-regressor tumor model, this new immunoregulatory circuit plays a role in suppressing CD8+ CTL-mediated immunosurveillance. • Abrogation of this pathway unmasks otherwise inapparent spontaneous natural tumor immunosurveillance and reduces tumor growth even in the absence of any vaccine or other immunotherapy.

  19. Enhancement of Vaccine Elicited CD8+ CTL response by in vivo treatment with an IL-13 inhibitor Immunization: PCLUS6.1-P18 +GM-CSF+CD40L % specific lysis E:T ratio Ahlers et al. PNAS, Oct. 2002

  20. INTRARECTAL IMMUNIZATION WITH SYNTHETIC PEPTIDE HIV VACCINE INDUCES BOTH SYSTEMIC AND MUCOSAL CTL TARGET CELLS + peptide - peptide Intrarectal Subcutaneous Immunization Immunization SPLEEN PEYER'S PATCH LAMINA PROPRIA 0 10 20 30 40 50 0 10 20 30 40 50 % SPECIFIC LYSIS AT 50:1 Belyakov et al. PNAS 1998

  21. Belyakov et al., JCI 1998

  22. Belyakov et al., JCI 1998

  23. Berzofsky et al., Nature Reviews Immunology 2001; Belyakov et al., Nature Medicine, 2001.

  24. Belyakov IM, Berzofsky JA, Immunity, 2004, Vol.20, 247

  25. Comparison of Mucosal Peptide or Poxviral Vaccine with Peptide-Prime, Poxviral Boost in Rhesus Macaques Prime Boost All animals received GM-CSF, IL-12, CpG, and LT(R192G) In DOTAP with or without peptide at the times of peptide priming.

  26. Peptide-Prime/NYVAC Boost Mucosal Vaccine Delays Acute Peak Viremia, Suggesting Delayed Dissemination from Mucosal Site of Transmission Belyakov et al., Blood, in press 2006

  27. 7 6 5 4 3 2 1 0 0 1 2 3 4 Strong inverse correlation between vaccine-induced Tetramer+CD8+ T cells in colon before challenge and viral load in blood after challenge r = -0.84; p<0.00001 Viral Load (log10) % CL10-Tetramer+CD8+ Belyakov et al., Blood, in press 2006

  28. No correlation between vaccine-induced Tetramer-binding T cells in blood before challenge and viral load in blood after challenge r = 0.007, p > 0.7 7- 6- 5- 4- Viral Load (log10) 3- 2- 1- 0- % CL10-Tetramer+CD8+ Belyakov et al., Blood, in press 2006

  29. Inverse Relationship with Viral Load is greater for high avidity CTL Day 17 after Challenge Low avidity Viral load (log10) High avidity Belyakov et al., Blood, in press 2006

  30. Conclusions • Natural transmission of many viruses is through mucosal surfaces. High avidity mucosal CTL may prevent or reduce dissemination from this site and abort the infection. • Mucosal immunization is most effective at inducing mucosal CTL. • CTL avidity is critical in clearing virus infections. • CTL avidity & longevity can be increased by immunization in the presence of IL-15 or costimulatory molecules. • Immunogenicity can be increased by • Use of appropriate cytokines • Epitope enhancement by sequence modification to increase binding to MHC molecules • Blockade of negative regulatory pathways, including NKT cells and T reg cells, IL-13 and TGF-beta

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