1. So tell me, this physician of whom you were just speaking, Is he a money maker, an earner of fees, or a healer of the sick? Plato, The Republic

2. Antigenic escape Inaccessible epitopes Downregulating MHC Destruction of CD4+ T cells Integration and latency Blocking Cytosine Deamination This formidable array of defense mechanisms Allows HIV to avoid being suppressed by our immune system How can we help the body fight back?

3. Antigenic escape Inaccessible epitopes Downregulating MHC Destruction of CD4+ T cells Integration and latency Blocking Cytosine Deamination This formidable array of defense mechanisms Allows HIV to avoid being suppressed by our immune system How about an AIDS vaccine?

4. Even 2,500 Years Ago, People Knew Immunity Worked. Greek physicians noticed that people who survived smallpox never got it again. The insight: Becoming infected by certain diseases gives immunity.

5. Vaccination Edward Jenner 1796 : Cowpox/Swinepox 1800’s Compulsory childhood vaccination Fast forward 2300 years

6. Smallpox 1% v. 25% mortality Life-long immunity UK: 1700’s China 1950 Pakistan/Afghanistan/Ethiopia 1970 pathmicro.med.sc.edu/ppt-vir/vaccine.ppt Variolation was a huge advance

7. Smallpox No animal reservoir Lifelong immunity Subclinical cases rare Infectivity does not precede overt symptoms One Variola serotype pathmicro.med.sc.edu/ppt-vir/vaccine.ppt Smallpox presented many advantages that made this possible

8. Smallpox As a result, after a world-wide effort Smallpox was eliminated as a human disease in 1979 pathmicro.med.sc.edu/ppt-vir/vaccine.ppt

9. Reported cases per 100000 population 100 10 1 0.1 0.00 1 0.01 1950 1960 19701980 1990 Inactivated (Salk) vaccine Oral vaccine Cases per 100,000 population United States Other vaccines have followed, making once feared diseases a thing of the past

10. How does vaccination work? A live or inactivated substance (e.g., protein, polysaccharide) derived from a pathogen (e.g bacteria or virus) capable of producing an immune response Expose the patient to an Antigen

11. A live or inactivated substance (e.g., protein, polysaccharide) derived from a pathogen (e.g bacteria or virus)capable of producing an immune response Expose the patient to an Antigen If the patient is subsequently exposed to infectious agent carrying this Antigen they will mount a faster immune response How does vaccination work?

12. Molecular Biology of the Cell Alberts et al Patient exposed to pathogen Carrying antigens A and B It works like this

13. Vaccines can be divided into two types Live attenuated Inactivated

14. Inactivated Vaccines fall into different categories viruses bacteria Individual proteins from pathogen Pathogen specific complex sugars Whole Fractional

15. Live Attenuated Vaccines have several advantages Attenuated (weakened) form of the "wild" virus or bacterium Can replicate themselves so the immune response is more similar to natural infection Usually effective with one dose

16. Live Attenuated Vaccines also have several disadvantages Severe reactions possible especially in immune compromised patients Worry about recreating a wild-type pathogen that can cause disease Fragile – must be stored carefully MMWR, CDC

17. A number of the vaccines you received were live Attenuated Vaccines Viral measles, mumps, rubella, vaccinia, varicella/zoster, yellow fever, rotavirus, intranasal influenza, oral polio BacterialBCG (TB), oral typhoid

18. Inactivated Vaccines are the other option No chance of recreating live pathogen Less interference from circulating antibody than live vaccines Pluses

19. Inactivated Vaccines are the other option Cannot replicate and thus generally not as effective as live vaccines Usually require 3-5 doses Immune response mostly antibody based Minuses

20. Inactivated Vaccines are also a common approach today Viral polio, hepatitis A, rabies, influenza* Bacterialpertussis*, typhoid* cholera*, plague* Whole-cell vaccines *not used in the United States

21. Other Inactivated Vaccines now contain purified proteins rather than whole bacteria/viruses Proteinshepatitis B, influenza, acellular pertussis, human papillomavirus, anthrax, Lyme Toxinsdiphtheria, tetanus

22. Sabin Polio Vaccine Attenuated by passage in foreign host (monkey kidney cells) Selection to grow in new host makes virus less suited to original host

23. Sabin Polio Vaccine Attenuated by passage in foreign host (monkey kidney cells) Selection to grow in new host makes virus less suited to original host Grows in epithelial cells Does not grow in nerves No paralysis Local gut immunity (IgA)

24. Salk Polio Vaccine Formaldehyde-fixed No reversion

25. US: Sabin attenuated vaccine ~ 10 cases vaccine-associated polio per year = 1 in 4,000,000 vaccine infections Scandinavia: Salk dead vaccine No gut immunity Cannot wipe out wt virus Polio Vaccine illustrates the pluses and minuses of live vaccines pathmicro.med.sc.edu/ppt-vir/vaccine.ppt

26. Reciprocal virus antibody titer 51 2 12 8 32 8 2 1 Serum IgG Serum IgM Nasal and duodenal IgA Nasal IgA Serum IgA Duodenal IgA Days Vaccination 4848 48969696 Killed (Salk) Vaccine Live (Sabin) Vaccine Live virus generates a more complete immune response

27. Modern molecular biology has offered new approaches to make vaccines

28. 1.Clone gene from virus or bacteria and express this protein antigen in yeast, bacteria or mammalian cells in culture

29. Modern molecular biology has offered new approaches to make vaccines 2. Clone gene from virus or bacteria Into genome of another virus (adenovirus, canary pox, vaccinia) And use this live virus as vaccine

30. Cloned protein antigens have pluses and minuses Pluses Easily manufactured and often relatively stable Cannot “revert” to recreate pathogen Minuses Poorly immunogenic Post-translational modifications Poor CTL response

31. Viral vectors have pluses and minuses Pluses Infects human cells but some do not replicate Better presentation of antigen Generate T cell response Minuses Can cause bad reactions Can be problems with pre-exisiting immunity to virus Often can only accommodate one or two antigens

32. Given that introduction, should we search for a vaccine against HIV and how would we do so? 30 million deaths caused by HIV 33 million living with HIV/AIDS 2.7 million new infections in 2008

33. An effective vaccine could have a MAJOR Impact on the future prognosis iavi.org

34. This allows T cells to recognize HIV infected cells, for example, and even internal proteins like reverse transcriptase can serve as antigens An effective vaccine must get around the strategies HIV uses to evade the immune system

35. This allows T cells to recognize HIV infected cells, for example, and even internal proteins like reverse transcriptase can serve as antigens The vaccine must be able to target conserved and essential parts of the viruses machinery Antigenic escape Inaccessible epitopes + existence of many viral strains

36. Molecular Biology of the Cell Alberts et al This allows T cells to recognize HIV infected cells, for example, and even internal proteins like reverse transcriptase can serve as antigens The vaccine must act early in the process Before the virus becomes firmly established And destroys the immune system Destruction of CD4+ T cells Integration and latency

37. There are many possible HIV Vaccine Approaches Protein subunit Synthetic peptide Naked DNA Inactivated Virus Live-attenuated Virus Live-vectored Vaccine Ramil Sapinoro, University of Rochester Medical Center

38. To begin we need to ask some key questions What should vaccine elicit?

39. To begin we need to ask some key questions What should vaccine elicit? Neutralizing antibodies to kill free virus

40. To begin we need to ask some key questions What should vaccine elicit? Neutralizing antibodies to kill free virus T cell response to kill infected cells OR

41. To begin we need to ask some key questions What should vaccine elicit? Neutralizing antibodies to kill free virus T cell response to kill infected cells OR OR BOTH?

42. The biology of HIV provides some clues

43. Remember the long term non-progressors Infected with a Nef mutant virus?

44. This would generate both an antibody and a T cell response Could this be used to generate a vaccine?

45. This prompted an experiment that demonstrated the feasibility of a vaccine

46. December 1992: Live attenuated SIV vaccine Lacking the gene Nef protected all monkeys for 2 years against massive dose of virus All controls died cell mediated immunity was key

47. However, this approach is still viewed as too risky to try on human subjects December 1992: Live attenuated SIV vaccine Lacking the gene Nef protected all monkeys for 2 years against massive dose of virus All controls died cell mediated immunity was key

48. Another effort attempted to use recombinant viral proteins as antigens in an effort to generate neutralizing antibodies

49. VaxGen made two different forms of gp120 from different HIV strains and began human trials after chimp testing

50. Human vaccine trials are large and very expensive

51. The trial was a failure, with only minor effects seen that were viewed as statistically insignificant NY Times

52. The next approach involved using viral vectors to try to also boost the T cell response

53. Many different viral vectors are being investigated but this trial used the human cold virus called adenovirus

54. They actually used three adenoviruses carrying three different viral proteins Gag Pol Nef

55. Early results suggested the immune system was being stimulated

56. The hotly awaited results were released at the 2007 AIDS Meeting

57. You be the judge—what happened?

59. This stunning failure led to a re-thinking of the approach

60. “DNA” vaccines are a novel approach

61. The field has decided in part to go back to the basics: how does HIV work and how can we assess vaccine success? Questions: For a vaccine what are the measures of protection? Can we overcome polymorphism? What are the key antigens? Attenuated or killed or neither? Is Mucosal immunity critical? Should it Prevent infection or prevent disease? What are the best Animal models How does HIV kill cells anyway?

62. However trials continue, but with more focus on the details of how they affect immunity