Phalguni Gupta

Research Interest: Cellular and molecular basis of HIV pathogenesis, Molecular mechanisms of sexual transmission of HIV, Development of microbicides against HIV, HIV CURE

Research Summary: Molecular Mechanism of Sexual Transmission of HIV: A novel in vitro cervical tissue based organ culture has been developed to study heterosexual transmission of HIV-1. This model system allows the maintenance of the natural architecture of the tissue in the organ culture as evidenced by histology and quantitative immunostaining of immune and non-immune cellular proteins. Infectious virus is found to be transmitted from cell-free as well as cell-associated HIV-1 across the mucosal barrier. The model is being used to determine mechanism of sexual transmission of HIV-1, especially in elucidating viral and cellular factors that are involved in transmission through epithelial layer of cervical mucosa. Recently this organ culture is being extended to study the mechanism by which Neisseria gonorrhea (NG) enhances HIV-1 transmission across cervical mucosa. Using this organ culture we showed that NG exposure to cervical tissues induced epithelial membrane ruffling and inflammatory cytokine response, reminiscent of in vivo situation. Furthermore, we identified the NG induced cellular factors that may be responsible for enhanced HIV-1 transmission across cervical mucosa.

Development of anti-HIV Microbicides: An U19 Cooperative Agreement grant was funded by NIH to perform studies of preclinical optimization of an antimicrobial peptide, retrocyclin in combination with and a nonnucloside reverse transcriptase inhibitor 5-chloro-3-phenylsulfonylindole-2-carboxamide (CSIC) to block HIV transmission and be non-toxic to human. Our multidisciplinary approach to microbicide development targets two different sites of HIV-1 replication (entry and reverse transcription) through a controlled-release ring formulated product or a self-dissolving film formulation, utilizes a novel ex vivo organ culture to test toxicity, inflammation and antiviral activity across cervicovaginal mucosa, and applies macaque models to study toxicity and efficacy. In designing the scope of the proposed topical microbicide program, we have focused on extensively evaluating safety and toxicity of candidate microbicides utilizing in vitro studies, tissue explants and animal models, as well as an expanded and innovative organ culture model to study the interaction of HIV-1 and common sexually transmitted infections (STI) in assessing antiviral activity of microbicides in the presence and absence of STI. Therefore, the proposed study will provide new tools and strategies for the prevention of HIV-1 transmission and their sequelae for women.

HIV CURE Study: Although potent antiretroviral therapy suppresses HIV infection to undetectable levels of plasma viremia, the stably integrated HIV genome continues to persist in long lasting resting CD4+ T cells (rCD4). To achieve a CURE from HIV infection, these latently infected cells must be eliminated or functionally rendered silent. Assessing strategies to eliminate latently infected cells require an assay that can accurately quantitate the size of the latent reservoir. Studies are being conducted to determine the size of the latent reservoir. Recently we have developed a novel assay (TZA) to quantitate latent reservoir that are sensitive, less time consuming, and can be automated for use in a high throughput setting. Furthermore, we developed dendritic cell (DC)-based stimuli that are more potent inducers of latent HIV activation than those reported in the literature. There are ongoing study to investigate the level of latently infected HIV in resting CD4 cells in longitudinally isolated PBMC from the Multicenter AIDS Cohort Study (MACS) subjects following therapy that has been initiated at early stages of infection and late stages of infection, and continued for at least 10 years.