Isolation and functional analyses of monoclonal antibodies against the HIV-1 antisense protein ASP from people living with HIV-1

About This Grant

PROJECT SUMMARY The antisense gene asp maps in the HIV-1 genomic region overlapping env at the SU/TM boundary. Asp is found in pandemic strains of group M, but not in other primate lentiviruses including non-pandemic HIV-1 groups N, O, and P. We showed that asp is highly conserved despite constraining the evolution of env. We also reported that the asp gene is found at a higher frequency in people living with HIV-1 (PLWH) who progress to AIDS in <3 years (rapid progressors) compared to those who progress to AIDS in >12 years (long term non-progressors). The asp gene encodes the 189-aa hydrophobic protein, ASP. We reported that ASP shows high sequence iden- tity across HIV-1 isolates from all group-M subtypes. Work from our lab described the presence of ASP on the plasma membrane of infected cells, and on the envelope of infectious HIV-1 particles. Our unpublished studies demonstrate that the presence of ASP on the surface of HIV-1 particles facilitates viral entry. Several studies have shown the presence of cellular and humoral immune responses to ASP in PLWH, which proves its expression in vivo. A recent report reported that antibodies against ASP were specific for epitopes in the predicted ectodomain of ASP. Our preliminary studies confirmed the presence of antibodies against the ASP ectodomain in Elite Controllers (EC). Yet, none of the studies published so far endeavored to isolate ASP anti- bodies from PLWH and to test their functional activity as a way to investigate the role of ASP in HIV-1 infection. The overall aim of this application is to isolate monoclonal antibodies (mAbs) against the ectodomain of ASP from EC, Viremic Controllers, and PLWH both on and off ART. We will test their activity in in vitro and ex vivo assays. These studies will be performed in collaboration with Dr. Mohammad Sajadi (Institute of Human Virology, University of Maryland School of Medicine), who has established a cohort of >200 PLWH from whom he has already obtained paired serum and PBMC samples that are immediately available for the studies proposed here. Dr. Sajadi has developed a method for the identification, isolation, and cloning of mAbs that led to the discovery of best-in-class mAbs against HIV-1, SARS-CoV2, and CCHFV. Here, we propose the following specific aims: In Specific Aim 1, we will generate pools of overlapping peptides that span the ectodomain of ASP, and we will use these peptide pools to screen serum samples from PLWH in Dr. Sajadi’s cohort to identify those with strong- est binding to each of the five ASP peptide pools, and to determine their peptide sequence specificity. Next, we will use single-cell PCR and mass spectrometry to isolate and clone high affinity anti-ASP mAbs from the paired PBMC samples of the same donors. We will then validate the ASP specificity of these mAbs in ELISA and virion capture assays. In Specific Aim 2, we will test the activity of the ASP mAbs in mediating antibody dependent cellular toxicity (ADCC), reducing viral entry in single-round infection and viral replication in multiple rounds of infection, and detecting ASP on the cell surface, in the cytosol, and within nuclei.