Browsing by Subject "retrovirus"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Studies On The Determinants Of HIV Mutagenesis And Strategies For Its Enhancement(2015-12) Rawson, JonathanHuman immunodeficiency virus type-1 (HIV-1) is one of the fastest evolving entities on earth, due in part to a mutation rate that is at least 10,000-fold higher than that of eukaryotic genomic DNA. The adaptability of HIV-1 prevents clearance of the virus by the immune system, promotes drug resistance, and has impeded development of effective vaccines. The viral mutation rate is a composite result of mutations that are contributed by multiple host and viral enzymes involved in viral replication. However, the precise determinants of viral mutagenesis in HIV-1 and the degree of their contribution to HIV-1 genetic diversity remain incompletely understood. Furthermore, differences in viral mutagenesis among different HIV types (e.g., HIV-1 and human immunodeficiency virus type 2, HIV-2) and subtypes have not been explored to date. Lastly, the elimination of HIV-1 infectivity by increasing the viral mutation rate has not been extensively investigated – in terms of mechanism of action and in preclinical and clinical evaluations. Based upon these general observations, this dissertation research was conducted to test the following hypotheses: 1) HIV-1 and HIV-2 have different mutation rates; 2) decitabine, a HIV-1 mutagen, creates G-to-C transversion mutations in the absence of mutational hotspots; 3) 5-azacytidine causes HIV-1 mutagenesis after reduction to 5-aza-2’-deoxycytidine (i.e. decitabine); 4) the anti-HIV-1 activity of 5-azacytidine is antagonized by inhibitors of ribonucleotide reductase; 5) the anti-HIV-1 activity of ribonucleotide reductase inhibitors are potentiated by 5,6-dihydro-5-aza-2’-deoxycytidine. The studies conducted in this dissertation advance current understanding of the determinants for retroviral mutagenesis, the mechanisms by which small molecules promote mutations in HIV-1, and approaches for using combinations of small molecules to reduce viral infectivity by enhancing the mutagenesis of HIV-1. Supplementary data (figures, tables, and spreadsheets) associated with this thesis are available online.Item Studies on the Molecular Determinants of Human Retrovirus Diversity(2021-09) Meissner, MorganThe human immunodeficiency viruses (HIVs) are two species (HIV type 1, HIV-1; HIV type 2, HIV-2) in the Lentivirus genus of the Retroviridae family of viruses and are the etiological agents of acquired immunodeficiency syndrome (AIDS). Nearly 75 million people have been infected with HIV-1 and HIV-2 since their emergence in the human population and they are responsible for the deaths of almost 32 million individuals to date. One of the key drivers of the HIV-1 pandemic is the extreme genetic diversity of the virus, which drives the development of antiviral drug resistance and frustrates vaccine development. Retroviruses also exhibit considerable structural diversity, which may have important implications for infectivity and replication. Human T-cell leukemia virus type 1 (HTLV-1), within the Deltaretrovirus genus, is also a major pathogenic human retrovirus. HIV-2 and HTLV-1 exhibit markedly reduced rates of transmissibility and potentially evolution compared with HIV-1 and are therefore understudied relative to their pandemic counterpart. The overarching goal of this thesis was to characterize the viral and cellular determinants of the molecular diversity of human retroviruses, with an emphasis on HTLV-1 and HIV-2. To this end, experiments were conducted which 1) characterized the structural diversity of authentic HTLV-1 particles derived from the chronically infected SP cell line, demonstrating that intact capsid cores are relatively rare among HTLV-1 particles; and 2) examined the contribution of host apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) proteins to HIV-2 mutagenesis, which revealed that despite their role as potent mutagens of HIV-1, APOBEC3-mediated mutagenesis of HIV-2 is limited. Additionally, a user-friendly sequence analysis workflow was developed that enables the ultra-accurate detection of mutations within HIV-1 and HIV-2, which reduces the background error rate of traditional Illumina next-generation sequencing by approximately 100-fold. This workflow is already being employed to characterize the contributions of additional cellular proteins to retroviral mutagenesis, including the host protein SAM domain and HD domain- containing protein 1 (SAMHD1). Taken together, these studies provide new insights into the structural and genetic diversity of human retroviruses, particularly those which have historically been poorly characterized and underappreciated.