Refresher: How Vaccines Work; Vaccine Research Today

1. Refresher: How Vaccines Work; Vaccine Research Today Jerald C. Sadoff MD AIDS Vaccine 2009 Journalist Scholarship Training Overview October 18th 2009 Paris, France

2. Topics to be covered • Refresher: How Vaccines Work • Basic principles in developing vaccines • Vaccine Research Today

3. Refresher: How Vaccines Work • The general answer • The battle between the bugs and us • Their Genes and our Genes • Timing and location are everything

4. The general answer how vaccines work • Vaccines work by fooling the body into thinking it is infected with a bug so that next time when it sees the real thing it will be ready faster with a more powerful response • Sometimes it gets the body to do something different and better then if it were naturally infected

5. The Battle Between Us and the Bugs:What we can do • We recognize them as something different not belonging inside the body • Once recognized we try and kill them • We have two systems of doing this: • The Innate system • The Cognate system

6. The Innate System • Ancient system found in almost all living things in some form • Recognizes patterns in pieces of the bugs rather then specific pieces • Immediate but no memory for next time • Poisons released quickly that kill everything around • Massive numbers of all kinds of cells called in rapidly that eat what they encounter (called inflammation)

7. Cognate System • Newer more sophisticated system found in higher animals which is dependent on the innate system • Recognizes very specific parts of the bug called antigens or epitopes • Comes up slower if hasn’t seen it before • It remembers from one time to the next • Its weapons: antibodies and T cells recognize and kill very precisely

8. Vaccines induce the cognate system to remember, recognize, and kill viruses, bacteria, parasites or cancer cells

9. The cognate system has 3 weapons: • Antibodies • White cells: Macs and Polys • White cells: T cells

10. Antibodies • Antibodies are proteins floating in our fluids and organs everywhere they can get • At one end they recognize and stick on the surface of the bug • When they bind bad things happen to the bug

11. White cells: Macs and Polys • Recognize the back end of the antibody stuck on the surface of the bug • They use the antibodies like a zipper to close around the bug and eat it • Once the bug is inside the cell its held in a bag and poisons are dumped in that kill it

12. White cells: T cells • Recognize our cells that have been infected by bacteria, viruses or parasites • They get very close to the infected cell • They secrete signals to the cell in very high concentrations that tell the cell to kill the bug • Some of these T cells are memory cells that live a long time and some are effectors that are out in the tissues ready to pounce

13. B - cell Central or Effector Memory CD 8 T cell CD 4 T cell antibodies TH2 TH1 TH1 TH2 IFN-γ IL-2 TNF-α IL-4 DTP, Hib, Pneumococcus, Measles, Polio, Hep B, Rotavirus, HPV, Malaria TB, Malaria, HIV

14. Battle with the Bugs: What they do • They protect themselves from innate White cell engulfment and killing • Bacteria like Pneumococcus build thick walls of sugar on their outsides that white cells cant engulf without the zipper of antibody – basis of the new pneumococcal vaccine • TB organisms poison the bag they are in inside the cell so they cant be killed once inside • Viruses like varicella hide in the nerves where white cells cant go

15. Battle with the Bugs: What they do • They move rapidly from one site to another so they are gone by the time the cognate system has responded • The malaria parasite is only in the blood for less then a minute before it gets to the liver and then it changes so adaptive antibody isnt made • It only stays in the liver for 10-14 days so that adaptive T cells are too slow • The new malaria vaccine induces both antibody and T cells that are ready for it

16. Battle with the Bugs: What they do • They avoid the cognate T cell response by changing the ability of the cells they have infected to show they are infected • Measles, CMV and HIV all turn down the ability of the infected cells to put pieces of the virus on its surface so that a cognate response is dampened

17. Battle with the BugsTheir Genes and Our Genes • They can change their genes rapidly because • They reproduce so fast • Sometimes like HIV they don’t reproduce very accurately • They are a population attacking us not an individual while we tend to be concerned about protecting each individual in our population

18. Battle with the BugsTheir Genes and Our Genes • We cant change our genes rapidly • We have a lot of genes • We have genes to make antibodies that can recognize just about everything including plastic that doesn’t exist in nature • We have genes for T cells that can recognize just about everything but each individual is unique on what pieces of viruses can be presented • We can slowly change our antibody genes

19. Battle with the Bugs: What they do • They can change so rapidly that they can out run the cognate responses • HIV changes its surface variable regions so that it avoids neutralizing antibody that develops • About 25% of humans eventually develop broad neutralizing antibodies • HIV changes the epitopes that are recognized by T cells within 10-20 days of first infecting humans thus avoiding that cognate response • HIV can eventually find something that it human host cant respond to

20. Battle with the Bugs: What they do • They misdirect the cognate system to immunodominant antigens that they can change and away from antigens they cant change • Gonorrhea and E. coli pilus antigens highly variable and immunodominant – distract from tip proteins that are required for attachment and sex • HIV gp120 variable regions are B cell dominant and can vary rapidly • HIV subdominant T cell antigens protect in the few animals that recognize them (Watkins)

21. Timing and Location are Everything • Timing - Vaccines work because the cognate response after vaccination is much faster when the bug is first seen then what occurs if it has to develop from scratch • Pneumococcal anti sera given within 3 days of hospitalization 40% survival after 3 days no survival • Most vaccines have very little effect after the infection has progressed since the system is already mounting a cognate response due to the infection • Rabies is an exception - following a rabid animal bite the virus travels slowly up the nerve to the brain – immediate immunization can save your life if the immunity develops before the virus gets there, that’s why a bite on the face is worse then the arm

22. Timing and Location are Everything • Location is important because the cognate immune response has to get to the pathogen rapidly to be effective • Only 4 of 8 sets of T cells directed exactly at the same piece of malaria worked to protect mice from malaria • The 4 that worked are the one that got to the liver

23. Studies with NIH VRC – Bob Seder, Mario Roederer

24. Timing and Location are Everything • An example of where timing and location are both thought to be critical is the protection induced by CMV vaccine against SIV infection to be further presented at this meeting by Louis Picker • The effector T cells induced by this vaccine are not only ready to kill at the time of infection but they are already located where the virus goes.

25. Basic Principles • Use what the disease gives you • Correlates and Surrogates make everything easy • When everything else fails – Proof of Principle studies and bootstrapping • Manufacturing – Vaccines are not iPods • Assays rule • Eternal triangle of risk vs time vs resources

26. What the disease gives you • Epidemiology – • Hemophilus type B – no disease till 4-6 month • Rotavirus – 2nd infection with different type • Zoster – more disease >65 years of age • High Attack rate – • Rotavirus - efficacy in 400 children • Malaria – efficacy in 2000 children

27. What the disease gives you • Animal Model – • Hep B - Non Human Primate • Pnumococcus, Hemophilus, • TB – (?) low dose NHP challenge • HIV- (?) SIV low challenge dose

28. What the disease gives you • Possibility of Human Challenge studies • Shigella • Cholera • Malaria • HIV (?)

29. Basic Principles • Use what the disease gives you • Correlates and Surrogates make everything easy • When everything else fails – Proof of Principle studies and bootstrapping • Manufacturing – Vaccines are not iPods • Assays rule • Eternal triangle of risk vs time vs resources

39. Basic Principles • Use what the disease gives you • Correlates and Surrogates make everything easy • When everything else fails – Proof of Principle studies and bootstrapping • Manufacturing – Vaccines are not iPods • Assays rule • Eternal triangle of risk vs time vs resources

40. RISK RESOURCES TIME

41. Vaccine Research Today • Antigens • Reverse Engineering • Bioinformatics • Epitopes • Vaccine Delivery • Adjuvants • Non-replicating vectors • Replicating vectors

42. Reverse Engineering • Utilizing molecular modeling and immune responses in protected volunteers to down select from thousands of possible proteins • Limited number of proteins put in mouse or other small animal studies • Recent promising examples: • Common Group B meningococcal protein • Common Pneumococcal protein • Common Staphylococcal protein

43. Reverse Engineering – Structural studies • Understanding the detailed molecular structure of a target protein and its interaction with antibody design an immunogen to induce that antibody • Influenza and HIV tremendous current work • Identified binding regions of monoclonals that neutralize somewhat broadly including new ones that bind V3 stem • So far unsuccessful in designing immunogen

44. Bioinformatics • Using scoring systems with internal validation combine all of the information about antigen candidates to select promising antigens for inclusion in vaccine vector • Example: TB antigens for inclusion in a recombinant BCG for over-expression

45. Rv2627c Rv2780 Rv1884c Rv2620c Rv2744c Rv3875 Rv1926c Rv2030c Rv3132c Rv3347c Rv0467 Rv1130 Rv1169c Rv1793 Rv2629 Scoring of Antigens Over-expressed/Up-regulated in AERAS-427 – From List of Top 45 Rv1738 Rv1733c Rv2029c Rv1996 Rv2450c Rv2389c Rv2623 Rv0685 32/45 top scoring antigens by bioinformatics analysis directly over-expressed or up-regulated in AERAS-427 Rv1009 Rv2628 Rv1980c Rv0867c Rv3804c Rv2031c Rv0079 Rv1886c Rv3130c Rv0288 Rv3131 Rv2032 Rv0824c Rv1908c Rv2626c Rv1174c Rv3873 Rv1349 Rv2005c Rv1813c Rv3127 Rv2006 Rv2029c

46. Epitopes • Fundamental problem in B and T cell based vaccines is epitope selection to cover the variety of pathogens that might be encountered • Second problem is the virus changing its epitopes • Third problem is immunodominance of some epitopes over others

47. Epitope Diversity • The approach with Pneumococcal, rotavirus and HPV vaccines is to make multiple serotypes (up to 16 for Pneumo) with the broadest epidemiologic coverage

48. Epitope Diversity- HIV • Informatics approach to combine all known variablility in the data base with natural segments and maximize coverage • Criticism of this is that the variability is escape to variants that cant be responded to • That this does represent incoming virus • Search for epitopes that cant vary because of their function

49. Epitope Immunodominance- HIV • Utilization of subdominant antigens in absence of dominant antigens • Sequential immunization • Immunization with separate vaccines

50. Vaccine Delivery - Adjuvants • Adjuvants stimulate the innate system – mainly through toll receptors • Several new adjuvants in clinical trials • AS04 with flu vaccines responses in 200-800 range compared to 20-60 for most flu vaccine • AS01-E in malaria and TB vaccines provide very high CD4 T cells in humans • IC-31 in TB vaccines induce CD4 T cells