Basic Science Award

HIV-infected individuals are at increased risk for a number of diseases typically associated with aging, including cardiovascular disease. It is now well accepted that poorly defined HIV-associated immunologic perturbations, in addition to traditional risk factors and antiretroviral therapy toxicity, contribute to this risk. This study will explore the pathogenesis of HIV-associated cardiovascular disease with a focus on telomere maintenance and aging.

Understanding the mechanism of HIV-1 transcription is key for developing a new class of antiviral drugs. HIV-1 Tat is an essential protein that transactivates HIV transcription by binding to the TAR region of HIV mRNA. p300-mediated acetylation of Tat is required for transactivation of the HIV long terminal repeat. Full activation of the HIV promoter also requires nuclear factor kappa-B (NF!B), which activates HIV transcription. Full activation of NF_B also requires p300-mediated acetylation.

Progressive depletion of CD4 T cells is a hallmark of HIV/SIV-induced AIDS. While HIV/SIV directly infects and kills CD4 T cells, the number of productively infected cells in vivo cannot account for the massive CD4 T-cell losses that occur. To gain a better understanding of this phenomenon, primary human lymphoid aggregate cultures (HLAC) from human tonsil and spleen tissue were examined. Three surprising discoveries emerged.

One of the remaining questions in HIV research is how the virus establishes a dormant (latent) state and thereby escapes eradication by current antiretroviral therapy. Latently infected T cells do not produce significant amounts of viral genomes or proteins due to the silencing of a specific step in the virus life cycle?viral transcription. Viral transcription can be reactivated in latently infected cells, a process that rekindles HIV infection after antiretroviral therapy is discontinued and remains a major barrier to eradication.

CD8+ T cells play an important role in inhibiting HIV replication through a non-cytotoxic antiviral activity. This response is mediated by a soluble CD8+ T cell anti-HIV factor (CAF). Several studies have shown that all known anti-HIV factors lack identity with CAF. CAF appears to be a novel anti-HIV protein. A great effort has been given to evaluating the gene candidates associated with CAF identified by DNA microarray procedures. The list of potential genes was narrowed down to twenty-five.

We have previously shown that infection-impaired HIV with incompletely processed capsid-spacer protein 1 (CA-SP1) is rescued by either cellular activation or increased expression of HSP90AB1, a member of the cytosolic heat shock protein 90 family of cellular chaperones. Expanding on our initial results, we found that HSP90AB1 is present in HIV virions and that recombinant HSP90AB1, but not nonfunctional mutated HSP90AB1E42A+D88A, restores infectivity to HIV with mutations in CA that alter core stability and impair infectivity.

Although macrophages are important in vivo targets for Human Immunodeficiency Virus Type 1 (HIV-1) infection, their relevance for the transmission, spread, and pathogenesis of HIV-1 remains unclear. This may be due to heterogeneity in subpopulations of macrophages, such that some but not all are permissive for infection. In part, this tropism could be related to tissue localization, but cell-intrinsic restriction factors, such as APOBEC3 and SAMHD1, have also recently been shown to exhibit direct antiviral activity.

Progressive depletion of CD4 T cells is a hallmark of untreated acquired immune deficiency syndrome (AIDS), but the mechanism of CD4 T-cell death by HIV remains poorly understood. While HIV directly infects and kills CD4 T cells, the number of productively infected cells in vivo cannot account for the massive CD4 T-cell losses that occur. To better understand how HIV infection depletes CD4 T cells, we used primary human lymphoid aggregate cultures (HLAC) from human tonsil and spleen tissue. Using this system three surprising discoveries emerged.

Detection of gene expression by flow cytometry is currently limited to transcripts that are abundantly expressed, however the recently reported RNAscope technology offers greatly improved sensitivity and specificity and has the potential to change the approach to single-cell transcript measurements that currently require low sensitivity approaches and are extremely low throughput. As yet these probes have not been utilized for study of patient samples by flow cytometry.

Sexual transmission accounts for most cases of HIV infection worldwide, with semen being the main carrier of viral particles during this process. Recent studies revealed that positively charged amyloid fibrils from human semen can substantially boost HIV infectivity rates. In two separate studies, M?nch et al. and our group identified two distinct HIV-enhancing semen amyloids.