Novel Approaches: Treatment and HIV Pathogenesis L. Trautmann, Ph.D. VGTI Florida

Beyond Anti-Retroviral Therapy ART reduces HIV viremia to undetectable levels and increases life expectancy, but... immune activation does not normalize under ART a small pool of latently infected cells persists under ART low levels of residual viral replication can persist during ART New strategies are being developed to: decrease inflammation under ART purge HIV latent reservoir under ART achieve a natural control of viral replication without ART Antibodies, cytokines, gene therapy, chemotherapy Cell-based immunotherapies and therapeutic vaccines

In Vivo and In Vitro Models of Intervention under ART New regimen of drugs in non-human primates to control viral load New in vitro models of viral reactivation and inhibition of viral replication

HIV-Specific CD8 T Cells can Eliminate Reactivated Reservoir Cells Stimulation of HIV-1-Specific Cytolytic T Lymphocytes Facilitates Elimination of Latent Viral Reservoir after Virus Reactivation Shan et al. Immunity 2012, 36(3):

Enhance T Cell Immunity Against HIV-1 DC Viral vector Protein DNA ADJUVANT High affinity Cross-reactivity High breadth High Cytotoxicity Poly-functionality High Proliferative Capacity Mucosal Homing TEMRA High Frequency of Effector Memory Long-lasting Central Memory VACCINE TCR Co-stimulation T CM T EM CD8 /CD4 T cell

HIV-Specific CD8 T Cells Fate Depends on Antigen Load Limit of detection Circulating virus HIV-specific CD8 T cells Time START ART When antiretroviral drugs suppress HIV to undetectable levels, HIV-specific CD8 T cells wane High levels of circulating viruses and HIV-specific CD8 T cells HIV-specific CD8 T cells decrease to low levels after ART initiation

HIV-Specific CD8 T Cells do not Control Viral Rebound Limit of detection Time STOP ART The virus rebounds after cessation of therapy as well as HIV-specific CD8 T cells Viral load reaches pre-ART level after ART cessation and is not controlled by the memory HIV-specific CD8 T cells Circulating virus HIV-specific CD8 T cells

CD8 T cells express different T cell receptors (TCRs) HIV-specific CD8 T cells can be detected using Tetramers of MHC I + HIV peptides recognizing the TCRs specific for these HIV peptides The TCR repertoire is the ensemble of T cell clones called clonotypes expressing different TCRs recognizing a specific antigen Each clonotype expresses a TCR encoded by a unique nucleotide sequence that can be used to track HIV-specific clonotypes in vivo Analyzing HIV-Specific CD8 T Cells under ART

HIV-Specific CD8 T Cells Wane with Antigen Decay

Phenotypic Changes after Antigen Decay Under low antigen load, HIV-specific CD8 T cells gain a more differentiated phenotype, express higher levels of IL7R and lower levels of negative regulator PD-1

Improved Function after Antigen Decay Low Ag Under low antigen load, HIV-specific CD8 T cells gain poly-functionality High Ag

TCR Repertoire Changes with Antigen Levels ART

Increased Function with Low Antigen at the Clonal Level Low Ag ART The same clonotype gained function after decrease of antigen load High Ag

Selection of Clonotypes with Superior Functional Capabilities Tetramer 1m17m TRBV 6-2 1m17m Low Ag ART Only the clonotype becoming dominant under ART gained function under low antigen load compared to the total epitope-specific CD8 T cells High Ag

Selection of Clonotypes with Superior Functional Capabilities HIV-specific CD8 T cells secreting cytokines upon restimulation before antigen decrease consisted only in the clonotype that became dominant under low antigen load

HIV-Specific CD8 T Cells under ART No ARTART Quality-+++ Quantity+++- Increase the number of HIV-specific CD8 T cells HIV-specific CD8 T cells

CD8 T Cells in Novel Approaches Defining strategies to increase the number of high affinity HIV- specific CD8 T cells would help in controlling viral reservoirs under ART and in controlling viral rebound after ART cessation High number of CD8 T cells under ART Control latent viral reservoir Efficient CD8 T cells at ART cessation Control viral rebound after ART withdrawal Achieve functional cure Drug free remission

Acknowledgements TRANSLATING RESEARCH INTO HEALTH VGTI Florida Rafick-Pierre Sékaly Elias Haddad Nicolas Chomont Glenda Canderan Abdelali Filali-Mouhim Montreal University Loury Janbazian McGill University Mohamad Rachid Boulassel Jean-Pierre Routy FRSQ-SIDAMI VRC NIH Daniel C. Douek David A. Price Richard A. Koup Tedi E. Asher David R. Ambrozak Phillip Scheinberg