Miami CFAR HIV Symposium

Transcription

1 Miami CFAR HIV Symposium Some Reflections on the Past Science in HIV/AIDS Research and Thoughts for Future Progress April 9, 2015 Robert C. Gallo, MD Director, Institute of Human Virology The Homer and Martha Gudelsky Distinguished Professor of Medicine University of Maryland School of Medicine Co -founder and Scientific Director, Global Virus Network Baltimore, Maryland

2 It Seems that Humans Have Only a 25 to 30 Year Memory Span Think of the great flu (influenza) epidemic of (forgot flu of 1889?-about 30 yrs before) Polio of the early 1950s (See David Oshinsky s book). (Forgot flu of 1918?-about 30 yrs) HIV of (forgot polio of 1950?-about 30 years before) -- In all 3, lessons of the prior epidemic were lost roughly years or so after the prior epidemic

3 Remarkable Biases of the Recent Past (1970s) Serious Epidemic infectious diseases are over in the industrialized world, therefore.. Retroviruses do not infect humans and there are many reasons for this... No viruses cause cancer in man.

4 In the early 1980S the Biases Were Shattered Viruses shown to be the cause of about 20% of human cancers. Retroviruses discovered in humans, shown to cause some leukemia's and neurologic diseases- HTLV and HTLV One of the great pandemics of history (AIDS) appears and is caused by another retrovirus.

5 AIDS and HIV: The Beginning of the Research AIDS is recognized in 1981 by US clinicians. CDC suggests several risk factors and Ideas of the cause are generated.

6 Ideas for the Cause of AIDS Begin in 1982, Some of the Notable Theories: Non-Infectious Poppers (amyl nitrate) (FDA) Autoimmunity to autologous leukocytes: (NIH)

7 Ideas for the Cause of AIDS Begin in 1982: Some of the Notable Theories Infectious A specific Adenovirus: (Albert Einstein Univ.) A specific EBV: (several groups) A specific CMV: (several groups) Mycoplasma: (Armed Forces Inst. Of Pathology) A new Fungus: early 1984 (NIAID) A new, T lymphotropic retrovirus: 1982 (NCI, Harvard) Ridiculous There is no cause and really no AIDS (Duesberg): 1984 to eternity. It was deliberately created (by the U.S. of course!!!).

8 What led to the idea of a new T cell tropic retrovirus as the best idea for the cause of AIDS? It was our experience with HTLV-1 and 2 HTLV-1 and 2---the 1 st and 2 nd human retroviruses discovered only just before AIDS (1979 and 1981). HTLV-1 causes T cell leukemia, fatal neurological disease, and moderate immune deficiecy. HTLVs are transmitted by blood, sex, and mother to infant--- these were related to risk groups described for AIDS by James Curran at CDC. HTLVs target CD4 + T cells, the very cells clinicians described as in decline in AIDS. So a new variant was the idea.

9 What were the keys to discovery of the HTLVs and then for the discovery of HIV? The story of HIV science and discovery is intricately related to the earlier discoveries of the HTLVs Sensitive and specific assay---this was the reverse transcriptase (RT) discovered in animal viruses by the late Howard Temin and by David Baltimore (1970). My colleagues and I, as well as D. Baltimore, made tests for RT very sensitive and sufficiently specific so it could be used as a surrogate marker for a retrovirus ( ). We discovered T-Cell Growth Factor now known as Interleukin-2 (IL-2) enabling us and others to grow human T cells in culture for the 1 st time a boom for immunology and a requisite for us in finding human retroviruses--- and for all labs in finding HIV. IL-2 was one of the earliest cytokines. A few points now on the HTLVs

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11 Global prevalence of Human T-cell Leukemia Virus type 1 (HTLV-1) Brown: 1-5% Tan: less than 1% Yellow: unknown

12 virus Retroviral integration patterns indicate causality If integration pattern is clonal, it indicates that the original cell giving rise to the tumor was infected, and implies that infection caused transformation. If integration pattern is random, it indicates that infection occurred only after transformation. virus

13 The Strategy of HTLV-1: (Its Survival) Depends upon propagation of the integrated DNA provirus BECAUSE THERE IS VERY LITTLE VIRAL REPLICATION Therefore, survival depends on T cell proliferation. Adult T cell Leukemia is the occasional accidental consequence. How does this occur?

14 LEGACY OF HTLV-1 FIRST HUMAN RETROVIRUS AND ONLY KNOWN LEUKEMIA VIRUS. ONLY HUMAN TUMOR VIRUS NOT KNOWN TO NEED ONE OR MORE CO-FACTORS. CAN PROVIDE CONTINUOUS GROWTH OF ANY MATURE CD4+ OR CD8+ T CELL. (useful in the lab.) INSIGHTS INTO THE MECHANISMS OF LEUKEMOGENESIS AND DEMYELINATING DISEASES PROVIDED CONCEPT AND TECHNOLOGY FOR THE DISCOVERY OF HIV.

15 What was the science of finding HIV and linking it to AIDS as the cause? 1) the clinical and epidemiologic information 2) the idea of a retrovirus-(1982) 3) the technology to grow human blood T cells (IL-2) (1976) and sensitive assays for a retrovirus (1970s) 4) first detection of a new retrovirus(1983) 5) linkage of HIV to AIDS by many isolates of the virus and a test (the HIV blood test) that allowed large scale screening and verification all over the world ).

16 T cell co-infected with HTLV-1 and HIV (Feb. 1983): from a tourist who received blood transfusions in Haiti

17 Finding the Virus Was One Thing; Showing Causation Was Another. AIDS Presented Unique Challenges Unlike Past Viral Epidemics or the Recent SARS Outbreak: 1. Clinical latency of 5-15 years 2. Multiple other microbial infections (which one was causative?) Several clinical-scientists were our critical collaborators, especially James Oleske (New Jersey Med), R. Redfield (Walter Reed), Jim Hoxie (U. Penn.), B. Haynes (Duke), J. Groopman (Harvard), M. Kaplan (Cornell) and Sam Broder (National Cancer Institute).

18 Frequent Detection or Isolation of Virus: A Total of 48 Isolates from 48 Different Patients in Our First Report in 1984 and 105 Isolates in Our Early 1985 Report as well as some Additional Isolates from Paris Were Still Nonetheless Probably Insufficient to Conclude That.

19 HIV Was the Cause of AIDS Because Verification is Necessary, and Verification by Virus Isolation Would Be Difficult Since: 1. Tissue specimens were limited and not even allowed in some institutions--the fear factor. 2. T cell culture technology was not widely available in virology labs at this time. 3. AIDS had to be clinically recognized, and by that time the patients generally had very few T cells to culture-making virus isolation very tricky. THE CONSEQUENCE WAS THAT VERY FEW GROUPS WERE INVOLVED

20 Fall of 1983 A Key Advance* Capacity for continuous cell line culture of five of our HIV isolates made several things possible: e.g., blood test, drug screening, detailed molecular analysis of HIV genes and proteins, etc. * My key colleagues in this work were Dr. Mika Popovic and my (and his) technician Betsy Read-Connole.

21 The Blood Test Was Able to Verify Etiology Because: The blood test was safe to work with simple to perform sensitive accurate inexpensive rapid Thus, verification was almost instant; it enabled surveys of thousands of sera samples globally

22 Development of the blood test Depended on a continuous and large scale production of HIV (as described in a previous slide). Based on a standard and sensitive immunoassay for patient serum antibodies specific to HIV (ELISA) as a screen. Confirmation and higher specificity with the Western Blot enabling detection of precise HIV proteins. This was the 1 st time the Western Blot was used in clinical medicine.

23 Major Practical Advances from HIV Research to date are: 1) Blood Test ) Anti-HIV Therapy-1986 first with AZT and then with the Combination of Drugs. The AZT Development was Historical.

24 Why The Blood Test Was the Key Advance It saved the blood supply, preventing blood transfusion infection as well as the consequent infections from the recipients. It allowed the epidemic to be followed for the first time. The culture system allowed the first screening for anti- HIV drugs. When therapy became available we could determine who to treat as well as block mother to child transmission. Critically, it also verified HIV as the cause of AIDS.

25 Needs for the Future CONTINUED RESEARCH ON NEW THERAPEUTIC APPROACHES. The push for a virological cure seems fanciful to me and, whereas a functional cure may be doable. What does that mean and how to approach it? BRINGING CORRECT THERAPY TO A MUCH HIGHER % OF INFECTED PERSONS. THE ULTIMATE-PREVENTING INFECTION AND ELIMINATING HIV. Test, test, test and treat ASAP, chemoprevention in the right setting, and of course a VACCINE is the ultimate.

26 Today the push is for a virological cure and the cry is to find the latently infected cells and kill them (purging or so called shock and kill )---while using anti-hiv drugs to block HIV spread when these memory T cells are activated. 26

27 In my view there are inherent problems with this view: 1) It is an assumption that reactivation of HIV from latently infected T cells leads to the death of all these cells. 2) It is an assumption that the anti-hiv drugs will completely prevent NEW infections from HIV released from the activated cells. 3) It is unlikely that the drugs used as activation agents can reach all the tissue sites of location of the latently infected cells.

28 Problems (continued) 4) The concept does not deal with infected macrophages and their related microglial cells of the brain see the classical studies of CFAR leader Mario Stevenson. These cells may be a continuous low level source of HIV. Short life spans of all subtypes of these cells is another assumption. 5) The approach depends on strict activation of proviruses without activating T cells, otherwise new activated uninfected T cells will be new HIV targets. Do we know that the activating agents in current use do not activate any of the CD4 T cell subtypes?

29 What is an alternative approach? Perhaps it is better to: 1) make major increases in outreach--- testing, testing, testing followed by quick therapy---especially in view of CDC data that 15% of US infected people do not know they are infected and another 20% are either lost to follow-up or improperly treated. 2) Continued development and use of safe, effective, and long lasting therapy such as the new integrase inhibitors and some of the neutralizing antibodies. Soothe and Snooze instead of shock and kill?

30 A vaccine against HIV can t be entirely based on principles from classical virus vaccinology because: HIV is a retrovirus-- and as such differs in critical ways from those viruses we have succeeded in developing successful vaccines.

31 What are the critical major differences? Its genome is RNA and it uses an error prone DNA Polymerase in its replication cycle leading to high variability. More importantly: its genes integrate in the host cell chromosomal DNA, and this occurs within about 24 hour soon establishing infection and providing little time for immune recall.

32 What are the consequences? Infection is established quickly and permanently with no time for immune recall. Therefore, a protective immune response must persist never before required for other vaccines. Complete block of infection (sterilizing immunity) may be required this too has never before a requirement for a successful vaccine.

33 Still another difficulty (but not so much of a problem) is: Need for a subunit vaccine, i.e., we cannot use a live attenuated virus (such as the Sabin Polio vaccine)---too dangerous, nor a killed whole virus (such as Salk Polio vaccine) also may be too dangerous and inactivation alters the outer envelope protein, gp120, in ways that it is not appropriately immunogenic. But we do have successful examples of subunit vaccines (Hilleman/Merck HBV for example).

34 So was Albert correct? A successful vaccine against HIV won t be doable. --Albert Sabin in late 1980s

35 Work from the primate centers with the SIV and subsequent SHIV macaque model Gave us most of our advances in the vaccine field as well as much in the pathogenesis field. Best results were from R. Desrossier years ago and came closest to proving an effective vaccine is possible- but approach raised safety issues.

36 The approaches with the major clinical trials (total of 6) to date 1) Based solely on cell mediated immunity (no antibodies) completely ineffective. 2) Adenovirus delivered HIV immunogens with or without antibody (Ab) generation actually increased infection. 3) Gp120 protein induced Ab failed likely because of mainly type specific antigp120 Abs. 4) Modified gp120 as protein as delivered by a pox vector with some other HIV proteins some success early-but fails some months after last boost (RV144).

37 Approach from the Institute of Human Virology (IHV) 1) The vaccine should induce protective Abs. 2) The Abs should target gp120 because it is the 1st thing which the cell sees and initiates the infection. 3) The Ab must be broadly reactive, targeting conserved regions which are functionally required by HIV for infection BUT these sites are hidden so.

38 so we opened internal hidden sites by methods which also fixed the mobile gp120, allowing Abs to bind several new epitopes.

39 HIV Binding and Fusion

40 HIV Binding and Fusion and Illustration of IHV Candidate Vaccine Vaccine is gp120 bound to D1D2 of CD4

41 Testing and Enabling the Concept: Single Chain gp120-cd4 Complexes Full length single chain (FLSC) Rhesus Full length single chain (rhflsc) Codon optimized BaL gp residue S-G-A Linker hcd4 (D1D2) Rhesus CD4 (D1D2) Human CD4 sequences for clinical testing; rhesus CD4 sequences for monkey studies

42 Viral Load Viral Load Patterns of Viral Replication in Sterilizing and Non- Sterilizing Protection in Monkey s with Heterologous challenges Non-sterilizing protection Sterilizing protection Challenge control group Challenge control group Vaccine group Vaccine group: protection Time Time Virus can be isolated from tissues at the end of the experiment in both groups. Virus can be isolated from tissues at the end of the experiment only in the control group, but as in the RV144 clinical trial protection was short lived

43 Loss of antibody persistence and and associated eventual loss of protection in the RV144 clinical trial 43

44 Attempting to solve the problem of failure of anti-gp120 Abs to persist: By adjuvants By vectors By using other HIV proteins Can cause loss of all efficacy! Why?

45 Antibody Persistence and T Cell Balance 45

46 Relationships Among ADCC, IFN-g Elispots, and the Number of Intra-rectal Challenges with SHIV162p3 Required for Infection: A zone of immune balance

47 Conclusions for an effective HIV vaccine: My View --- Even if we have the perfect ENV immunogen lessons from RV144 and Monkey studies show that: 2 Critical Basic Science Problems remain that must be solved for a successful anti-envelope HIV vaccine: Durability of the antibodies A correct immune balance (My key co-workers on the vaccine candidate from IHV are :Tim Fouts of Profectus and George Lewis and Tony DeVico of IHV).

48 In 1985 the late Jonathan Mann of WHO called HIV/AIDS research the fastest progress in the history of medicine from the inception of a new and mysterious epidemic. But we could have done better because though technically prepared I believe we were not prepared conceptually. In fact the only responsible groups were the WHO (no labs) and the CDC limited by their US government auspices and by the fact that though excellent cannot be experts in every thing. In fact the labs that made the greatest progress at the onset of the problem had no responsibility and became involved almost whimsically. For this reason I co-founded with Billy Hall of Dublin and the late Reinhard Kurth of Berlin-- the GLOBAL VIRUS NETWORK (GVN).

49 GVN s Mission To strengthen medical research and response to current viral causes of human disease and to prepare for new viral pandemic threats. GVN meets its mission in three ways: --Supports cutting edge research and training --Provides authoritative information to the public and policymakers about viruses, vaccines, treatments --Advocates for resources for medical virology worldwide.

50 Global Virus Network: composed of experts that cover all types of known viruses and who are available for advice, training and targeted research Centers of Excellence

51 The Threat of Outbreaks is Constant: some current examples GVN is focused on Influenza SARS MERS Ebola Dengue Norovirus Chikungunya HIV Various encephalitis viruses

52 Thank you for the invitation and the opportunity to see several friends once again. 52