Project 2 - Development of HLA-E-peptide antibodies for enhancing NK and CD8 killing of HIV infected CD4 T cells in vivo

ABSTRACT Natural Killer (NK) cells and CD8+ T cells play critical roles in immune surveillance, and their activity is mediated by a balance of stimulatory and inhibitory signals. The NKG2A/CD94 heterodimeric inhibitory receptor, found on subsets of NK cells and CD8+ T cells, interacts with the non-classical HLA class Ib molecule HLA-E to limit NK and T cell activation. HLA-E binds a restricted subset of peptides called VL9 that derive from the leader sequence of HLA class 1a molecules. Antibodies developed by us against HLA-E-VL9 and by others against NKG2A/CD94 disrupt the NKG2A/HLA-E-VL9 checkpoint and lead to NK and T cell activation. In addition to VL9, HLA-E can also display viral peptides, such as Rev IL9, RL9, or KF11, derived from HIV proteins. Targeting of HLA-E displaying HIV-derived peptides is a promising way to clear HIV-infected cells during acute retroviral infection, as demonstrated by multiple published studies and our preliminary data. Building on these findings, the central hypothesis of this project is that high-affinity antibodies against HLA-E-VL9 and HLA-E-HIV peptide complexes will enhance NKG2A+ NK and CD8+ T cell cytotoxicity, promote NK cell ADCC of HIV-infected CD4+ T cells, and potentiate the anti-HIV activity of engineered T cells from Project 1. This hypothesis will be tested by engineering and characterizing high-affinity antibodies against HLA-E-VL9 (Specific Aim 1) and HLA-E-HIV peptides (Specific Aim 2) and by evaluating their safety (Specific Aim 3). Antibodies with high affinity and specificity against HLA- E-peptide complexes will be developed using structure-based design, library screening, AI-based modeling, and state-of-the-art high throughput B cell receptor isolation, sequencing, and antigenic characterization. The resulting HLA-E-peptide monoclonals will be characterized biochemically, structurally, in cellular assays, and in vivo to assess their ability to enhance NK and T cell activity of killing of HIV-infected cells. Anti-HLA-E antibodies with acceptable safety profiles will be combined with T cell therapies developed by Project 1 and tested in relevant animal models of HIV infection in Project 3. Success in this project will provide a powerful new therapeutic approach that can be combined with existing cure AIDS strategies to reduce proviral DNA in the latent pool of HIV-infected CD4+ T cells in humans.