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

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

Epidemiological manifestations of hepatitis C virus genotypes and its association with potential risk factors among Libyan patients

<p>Abstract</p> <p>Background</p> <p>The information on hepatitis C virus genotypes and subtypes among Libyan population and its association with various risk factors is not known. The objectives of this study were to determine the epidemiological manifestations of HCV genotypes among Libyan patients and their association with certain potential risk factors.</p> <p>Methods</p> <p>A total of 1240 of HCV infected patients registered at Tripoli Medical Centre were studied in five years period from January 2005 to October 2009. The information were reviewed and the data were collected. A sample from each patient (785 male; 455 female) was analysed for genotyping and sub-typing using specific genotyping assay. The information was correlated with the risk factors studied and the statistical data were analyzed using SPSS version 11.5.</p> <p>Results</p> <p>Off the total patients studied, four different genotypes were reported, including genotypes 1, 2, 3, and 4. Genotype4 was the commonest (35.7%), followed by genotype1 (32.6%). According to subtypes 28% were unclassified genotype 4, 14.6% were genotype 1b and some patients infected with more than one subtype (2.3% genotype 4c/d, 1% genotype 2a/c). Genotypes 1 was the commonest among males, while genotype 4 among females. According to the risk factors studied, Genotype1 and genotype 4 were found with most of the risk factors. Though they were particularly evident surgical intervention, dental procedures and blood transfusion while genotype 1 was only followed by genotype 3 mainly which mainly associated with certain risk groups such as intravenous drug abusers.</p> <p>Conclusion</p> <p>Here in we report on a detailed description of HCV genotype among Libyans. The most common genotype was type 4 followed by genotype 1, other genotypes were also reported at a low rate. The distribution of such genotypes were also variable according to gender and age. The commonly prevalent genotypes found to be attributable to the medical -related transmission of HCV, such as blood, surgery and dental procedures when compared with other risk factors. This however, raises an alarming signal on the major steps to be taken to reduce such infection in Libya</p

Downregulation of HLA-I by the molluscum contagiosum virus mc080 impacts NK-cell recognition and promotes CD8+ T-cell evasion.

Molluscum contagiosum virus (MCV) is a common cause of benign skin lesions in young children and currently the only endemic human poxvirus. Following the infection of primary keratinocytes in the epidermis, MCV induces the proliferation of infected cells and this results in the production of wart-like growths. Full productive infection is observed only after the infected cells differentiate. During this prolonged replication cycle the virus must avoid elimination by the host immune system. We therefore sought to investigate the function of the two major histocompatibility complex class-I-related genes encoded by the MCV genes mc033 and mc080. Following insertion into a replication-deficient adenovirus vector, codon-optimized versions of mc033 and mc080 were expressed as endoglycosidase-sensitive glycoproteins that localized primarily in the endoplasmic reticulum. MC080, but not MC033, downregulated cell-surface expression of endogenous classical human leucocyte antigen (HLA) class I and non-classical HLA-E by a transporter associated with antigen processing (TAP)-independent mechanism. MC080 exhibited a capacity to inhibit or activate NK cells in autologous assays in a donor-specific manner. MC080 consistently inhibited antigen-specific T cells being activated by peptide-pulsed targets. We therefore propose that MC080 acts to promote evasion of HLA-I-restricted cytotoxic T cells