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Title: Genetic, structural, and functional exploration of the restrictive capacity of TRIM proteins against immunodeficiency viruses
Author: Simpson, Shmona
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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HIV-2 differs from HIV-1 in that many infected people experience normal survival, whilst only 20% progress rapidly to AIDS. Understanding mechanisms of delayed HIV-2 disease progression could provide new insights into HIV control. The Caio Community Cohort was established in Guinea-Bissau in the setting of high HIV-2 prevalence. This thesis investigates the role of polymorphic host restriction factors of the TRIM family in HIV-2 outcome. TRIM proteins are a family of E3 ubiquitin-ligases, where closely-related TRIM5α and TRIM22 are thought to inhibit HIV-1 transcription, uncoating and budding. There was an association between TRIM5α amino acid substitution R136Q and reduced HIV-2 viral load/prolonged survival. Conversely, P479L was enriched among HIV-2 infected participants and progressors with CD4+ T cell decline. TRIM22 was highly polymorphic in this cohort, revealing three novel coding variants. Although most substitutions were located in the putative virus-interacting PRYSPRY domain, two in the coiled-coil, D155N and R242T, showed significant and divergent associations with survival. R242T was enriched in HIV-2 infected participants, who progressed to death at twice the rate of wild-type controls. In silico studies predicted D282, D360, and R321 of TRIM22 to be highly conserved, exposed residues, for which polymorphisms would be deleterious. When aligned with sequences from the potent HIV-1 restriction factor, rhesus macaque TRIM5α, TRIM22 substitutions R321K, T415I, and D360Y were spatially relevant to residues involved in HIV-1 restriction. The role of TRIM22 in HIV restriction was supported by in vitro pilot studies showing that TRIM22 was upregulated by HIV-1 infection in a lymphoid cell line and co-localised with the HIV-1 capsid protein p24. Overexpression of TRIM22 resulted in the restriction of VSV-G pseudotyped HIV-1 and SIVmac. The R242T substitution diminished TRIM22's restriction of HIV-1 and SIVmac: protein analysis suggested that this may be due to the inability of the R242T mutant to fully dimerise.
Supervisor: Rowland-Jones, Sarah ; Carrington, Mary Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Medicine ; Infectious Disease ; Global Health ; Immunogenetics ; Host Restriction Factors ; Population Genetics ; HIV-2 ; HIV-1 ; TRIM22 ; West Africa ; TRIM5