1. Main questions on HIV persistence and on obstacles to HIV eradication Jean-Pierre Routy M.D. McGill University Montreal Toward an HIV cure: Insight into residual viral replication, establishment of HIV reservoirs and understanding mechanism of persistence

2. IAS international working group:

4. Even best candidates are not cured by HAART: “The Toronto patient” Early infection treatment, plasma VL < 50 copies, x 10,5 years HIV DNA undetectable from blood and sigmoid tissues at the time of the analysis HAART discontinuation Chun, Kovacs, Fauci AIDS 2010; 24:2803

5. The Berlin patient: Treated for acute myeloid leukemia by allo-stem cell transplatation

6. “The Berlin patient”

7. ABC news December 17, 2010 “A risky and inconvenient method” ABC News December 17, 2010

8. What does cure mean ? Sterilizing cure: –No genetic material can be found in the host, HIV infection is eradicated “Pax romana” or functional cure: –Some HIV genetic material remains in the host, but the immune system fully controls viral replication in absence HAART

9. Why HAART does not cure HIV ? HAART only blocks HIV replication/entry HAART does not kill infected cells: –The immune system should eliminate infected cells like –Persistence in long-lived cells –Integrated into the host cell nucleus –HIV DNA survives as long as the cell –9% of our human genome is also made from old integrated retroviruses

10. What do we know on HIV-infected cells under HAART ? Hematopoietic cells +/- Macrophages + Microglia + Memory CD4 T cells +++

11. Heterogeneity of the infected memory CD4 T cells Naive Central memory Transitional memory Chomont et al Nat med 2009

12. Why residual viremia persists with HAART (few copies only) ? Ongoing low viral replication: –Not allowing drug resistance development –New cells been infected –Reservoir maintained by replenishment –Localization: Lymphoid tissues Anatomic sanctuaries: CNS –Lower antiretroviral drug penetration –More antiretroviral drugs should do better

13. Residual plasma viremia and size of pro viral DNA in treated patients Chun, Kovac, Fauci et al JID 2011; 204:135 No correlation between CD4 and CD8 CD38 ceils and reservoir size Reservoir size Viral load < 50

14. Why residual viremia persists with HAART (few copies only) ? Viral production by infected cells not undergoing lytic cell death –Decay kinetic with a flat phase 3 –Long lived cells –Virus released when cells divide Central memory CD4 T cells: TCR dependant Transitional memory CD4 T cells: Homeostatic T cell proliferation associated with T cell activation Mathusalem: 969 years old

15. Role of T cell activation in the establishment and maintenance of reservoir Chomont et al Nat Med 2009 Da Fonseca et al IAS MOPE082 ActivationProliferation

16. Factors associated with CD4 T cell activation may impact reservoir size Corbeau P, J Reynes, Blood 2011; 117:5582 adapted LDL

17. What are the relative contribution of mechanisms associated with HIV persistence on HAART ?

18. Obstacle to HIV eradication

19. Timing of HAART initiation and the reservoir size and localization Limiting the pool of latently infected cells Preserving immune functions Reducing gut associated lymphoid tissue damage and in turn limiting subsequent inflammation triggered by systemic leakage of microbial products Can this strategy be implemented on a large scale ?

20. CD4/CD8 ratio and duration of viremia drive the reservoir size Chomont et al. Nat Med June 2009

21. HAART intensification Can HAART intensification completely suppress residual viral replication ? Is there a threshold for a functionally important decay of the latent reservoir following intensified HAART ? How long should we intensified treatment before assessing reservoir changes

22. Long-lived CD4 T cells: The Trojan Horse issue Mechanisms involved in the generation and maintenance of memory CD4 T cells are also responsible for the establishment and persistence of HIV in the long-lived cellular compartment Laocoonte, Vatican Museum “Do not trust the Horse, Trojans Whatever it is, I fear the Greeks even bearing gifts”

23. Tools to monitors reservoir changes Type of tests: –Ultra sensitive plasma viral load (RNA) –HIV DNA: integration –2-LTR: replication –Integrated DNA infectious units –Cell associated RNA Validation Frequency of sampling

24. Tissue sampling for monitoring of HIV persistence Blood: –Leukapheresis Lymph nodes Gut: –Rectum, colon, ileum Central nervous system: –CSF Genital fluids

25. Ethical and clinical trial issues Toxicity of experimental therapy(ies) Drug-drug interaction Reservoir assessment: –Tissue markers –HAART discontinuation as a read out for study outcome Quality of the informed consent Study design

26. “Higher risk, higher hope”

27. Conclusion Key topic at the Rome IAS conference Translational research challenge Community participation International collaboration

28. Acknowledgement Université de Montréal: –Patricia Montéro –Annie Gosselin –Petronela Ancuta –Cécile Tremblay –Rejean Thomas –Benoit Trottier –Jean–Guy Baril –Harold Dion VGTI Florida –Rafick Sékaly –Nicolas Chomont Cytheris: IL-7 –Michel Morre –Thérèse Croughs Université McGill: –Rachid Boulassel –Bertrand Lebouché –Roger LeBlanc –Richard Lalonde –Marina Klein –Martin Potter –Alexanda de Pokomandi –Norbert Gilmore –Mark Wainberg CIHR /CTN: –Joel Singer –Jacquie Sas –Jo Pankovich –David Cox

30. T cell survival and homeostatic proliferation Chomont, Sekaly et al Curr opin in HIV AIDS 2011;6: 30

31. Model for persistent infection in hematopoietic progenitor cells Mcnamara et al Curr Opin HIV AIDS 2010; 6:43

32. Diversité des formes du réservoir viral: Cellules latentes et productives

33. Cohen J Science; 2011; 332:784