Investigating HIV-1 Resistance to Broadly Neutralizing Antibodies Through Ex Vivo Viral Outgrowth Assays 9232

Abstract Description Anti-HIV-1 broadly neutralizing antibodies (bNAbs), which target conserved epitopes on the HIV-1 envelope glycoprotein, have been tested in clinical trials as long-acting alternatives to current antiretroviral therapies. We developed an ex vivo viral outgrowth assay to investigate the sensitivity of viruses obtained from the lymphocytes of people living with HIV (PLWH) to bNAbs. This approach is used to guide the development of newly discovered bNAbs and multispecific monoclonal antibodies. In this assay, CD4 T cells from PLWH are activated in vitro to stimulate HIV-1 replication and mixed with activated CD4 T cells from anonymous HIV-uninfected donors. When the co-culture starts producing p24, the HIV-1 capsid protein, the cells are divided, incubated with bNAbs, and monitored for p24 production over two weeks. To address whether variation in the ability of bNAbs to suppress viral outgrowth reflects the selection of de novo mutations during the assay, or from pre-existing bNAb-resistant quasispecies, we used HIV-1 infected lymphocytes obtained from different volunteers and conducted deep sequencing of the HIV-1 env gene of virions propagated in the presence of bNAbs or control antibodies. The sequencing results identified unique patterns of adaptation to selection by bNAbs of different classes. This work advances an understanding of HIV-1 antibody resistance mechanisms that inform the design of next-generation bNAbs and combination bNAb therapies. Topic Categories Vaccines and Immunotherapy (VAC)