P16-37. HIV controllers with weak CD8+ T cell responses maintain a tight control of infection despite carrying infectious viruses

International audienc

HIV-1 concentrates and shelters cell-associated infectivity a “viral biofilm”: Oral abstracts of the 21st International AIDS Conference- Abstract #WEAA0102

International audienceBackground: Highly active antiretroviral therapy (HAART) does not allow the complete clearance of the virus since it does not target viral reservoirs nor efficiently block HIV-1 cell-to-cell transmission in vivo. HIV-1 cell-to-cell spread is thousands-fold more efficient than cell-free infection; yet, how virions are transferred via cell contacts remains unknown.Methods: Using a panel of cutting-edge imaging techniques (Cryo- TEM, CL/SEM, CL/FIB and super-resolution imaging) to functional assays, we investigated and characterized viral structures involved in HIV-1 cell-associated infectivity. We analysed a range of infected T-cell cultures (chronically infected T-cell lines, primary CD4+ T cells infected in vitro with virus primary isolates and CD4+ T lympho- cytes from untreated HIV-1-infected patients with a detectable viraemia).Results: We show here that HIV-1 cell-associated infectivity mostly resides at the surface of CD4+ T lymphocytes in a viral biofilm, formed by viral particles aggregated within a scaffold ofextracellular matrix (ECM) components. Our set of data demon- strates that (i) biofilm-associated viral particles are more effi- cient in establishing infection than free viral particles and (ii) they confer HIV with important properties characterizing cell-to- cell spread. This includes the decreased sensitivity to HAART and to the broad neutralizing antibody 3BNC117. HIV-1 regu- lates biofilm matrix composition that controls both viral parti- cles organization at the cell surface and the resulting cell- associated infectivity. The organized clustering of viral particles along an ECM framework locally concentrates virions, favours their collective transfer to target cells and limits their exposure to nAbs. Finally, CD4+ T cells from HIV-1-infected patients pro- duce and transmit viral biofilms, supporting that they may also be involved in vivo.Conclusions: This study thus unveils HIV biofilm as a new highly infectious extracellular entity that concentrates, stores, dissemi- nates and shelters HIV-1 infectivity. This may have implications for HIV-1 spread and persistence in host, including for maintain- ing HIV-1 sanctuaries in treated patients. Our results unveil a new role for the ECM in clustering and protecting HIV-1 at the plasma membrane and in their collective transfer through viro- logical synapses. Targeting biofilm ECM components could repre- sent a promising approach to favour HIV-1 clearance or to potentiate the effect of available anti-viral therapies

Ex vivo T cell-based HIV suppression assay to evaluate HIV-specific CD8+ T-cell responses

International audienceTo advance T cell-based HIV vaccine development, it is necessary to evaluate the immune correlates of a protective CD8(+) T-cell response. We have developed an assay that assesses the capacity ex vivo of HIV-specific CD8(+) T cells to suppress HIV-1 infection of autologous CD4(+) T cells. This assay directly reflects the ultimate effector function of CD8(+) T cells, the elimination of infected cells, and accurately differentiates the effective CD8(+) T-cell response in spontaneous HIV controllers from ineffective responses in other patients. In this article, we describe all the steps from cell purification to assessment of viral replication by HIV-p24 ELISA and analysis, along with conditions for cell culturing, and how to choose the viral infectious dose that gives the most reliable results. We also depict the conditions of a rapid assay on the basis of flow cytometry analysis of intracellular HIV-Gag products. These procedures take 14-17 d when the p24 ELISA assay is used, or 6 d with the intracellular Gag assay