Interventions towards a functional cure: detailed phenotyping of the HIV-specific polyfunctional CD8+ T cell responses of controllers

Combined antiretroviral therapy (cART) has dramatically improved the clinical outcome of HIV-1 infected patients. Successful cART requires nevertheless lifetime adherence, has no effect on the eradication of viral reservoirs and do not restore an effective virus-suppressive immune response against HIV. An urgent need exists for developing an HIV cure overcoming the important limitations of cART including treatment resistance, adverse effects in the medium-long term and high financial cost. HIV cure could be achieved either by completely clearing the virus from the host (sterilizing cure) or by inducing host-mediated control of viral replication in the absence of cART (functional cure). Functional cure is spontaneously achieved in a small proportion (1%) of HIV-infected patients characterized by low or undetectable viraemia and stable CD4+ T-cell counts for many years without the need of cART. Although these so-called HIV Controllers contained different subpopulations and have multiple underlying mechanisms of immune defense, efficient CTL responses represent a critical component of spontaneous viral control. Apart from spontaneous controllers, there is a growing body of evidence that stopping treatment in a carefully selected population may not only be safe but also lead to a natural control of HIV infection. These post-treatment controllers (PTC) showed an extremely low HIV reservoir before interrupting treatment, the absence of HIV transcription, a low viral fitness but suboptimal CD8+ T-cell responses. The common characteristic of PTC and ECs is an exceptionally low proviral DNA reservoir. All in all this highly intricate picture of viral control supports the idea that thorough characterization of the CD8+ T cells responses targeting the viral reservoirs in longitudinal samples of different type of HIV controllers are still required. The aims of the study are (1) to correlate the cytotoxic/polyfunctional HIVspecific CD8 T cells subsets in different viral controller populations to the size and characteristics of the viral reservoirs (measured by digital droplet PCR) using the viral inhibition assay in vitro. A detailed phenotypic and functional characterization of HIV specific CD8 T cells will be performed using18 colors flow cytometry frames addressing polyfunctionality, cytotoxicity, exhaustion, differentiation, clonal turnover and coinhibtion. Bioinformatical analysis will be done in collaboration with a team from LIH using computational tools such as combinatorial polyfunctionality analysis of antigen specific T-cell subsets (COMPASS). These subsets will be further sorted and analysed for their gene expression profiles using Affymetrix microarrays in collaboration with a micro array group from LIH. To compare this phenotype to the one of c-ART treated humanized mice receiving an mRNA based therapeutic vaccination formula encoding for Trimix and the HIVACAT antigen enhancing efficient CD8 T cell responses, and (3) to define correlates of protection in the context of the ISALA trial. The ISALA trial is a prospective trial with structured treatment interruption of HIV infected and cART taking patients set on therapy during acute phase of infection. The focus of this trial will be screening for post treatment control.

Trefwoorden:B780-tropische-geneeskunde