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Analysis of MHC-I homologues in molluscum contagiosum and human cytomegalovirus

Elasifer, Hana 2018. Analysis of MHC-I homologues in molluscum contagiosum and human cytomegalovirus. PhD Thesis, Cardiff University.
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Abstract

Molluscum contagiosum virus (MOCV) and human cytomegalovirus (HCMV) each encode two MHC-I homologues: mc080 and mc033 in MOCV, UL18 and UL142 in HCMV. Codon optimised versions of the mc080 and mc033 genes were cloned in to a second-generation lentivirus system, vaccinia virus and a replicationdeficient adenovirus (Ad) vector. MOCV mc033 and mc080 were expressed from the Ad vector as endoglycosidase H (EndoH) sensitive glycoproteins with apparent molecular weights of 64kDa and 44kDa respectively, both localised predominantly to the ER. MC033 had no effect on either MHC-I or HLAE expression, nor did it impact NK cells or T cell function. MC080 downregulated cell surface expression of classical HLA-I and HLA-E in a TAP independent, although not MICA/B. This downregulation of HLA-1 correlated with protection against CD8+ T cell activation, thus MC080 is here identified as a novel viral T cell evasion function. MC080 was capable of supressing or activating NK cell, depending on context and consistent with MC080’s control of HLA-I and HLA-E. UL142 expression was enhanced by optimising codon usage and through provision of an alternative leader sequence. Using an Ad vector, UL142 was expressed as a heavily glycosylated 105kDa protein that localised to the ER, cell surface and was released into the supernatant in an EndoH-resistant form. When over-expressed from the Ad vector UL142 suppressed full length MICA, but not in the context of a productive HCMV infection where that function was performed by the US12 gene family. Preliminary allogenic functional NK cell assays showed UL142 to suppress NK cell function in one of four donors. However, cell-associated and secreted UL142 both activated NK cell degranulation when the assay was moved to an autologous setting. The results suggest that UL142 can modulate NK cell function independently of MICA.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Medicine
Date of First Compliant Deposit: 30 April 2019
Last Modified: 30 Apr 2019 09:26
URI: http://orca.cf.ac.uk/id/eprint/121984

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