The Irish paradigm on the natural progression of hepatitis C virus infection: an investigation in a homogeneous patient population infected with HCV 1b (Review)

The aetiological agent of chronic hepatitis C is the hepatitis C virus. The hepatitis C virus is spread by parenteral transmission of body fluids, primarily blood or blood products. In 1989, after more than a decade of research, HCV was isolated and characterised. The hepatitis C viral genome is a positive-sense, single-stranded RNA molecule approximately 9.4 kb in length, which encodes a polyprotein of about 3100 amino acids. There are 6 main genotypes of HCV, each further stratified by subtype. In 1994, a cohort of women was identified in Ireland as having been iatrogenically exposed to the hepatitis C virus. The women were all young and exposed as a consequence of the receipt of HCV 1b contaminated anti-D immunoglobulin. The source of the infection was identified as an acutely infected female. As part of a voluntary serological screening programme involving 62,667 people, 704 individuals were identified as seropositive for exposure to the hepatitis C virus; 55.4% were found to be positive for the viral genome 17 years after exposure. Of these women 98% had evidence of inflammation, but suprisingly, a remarkable 49% showed no evidence of fibrosis. Clinicopathology and virological analysis has identified associations between viral load and the histological activity index for inflammation, and, between inflammation and levels of the liver enzyme alanine aminotransferase. Infection at a younger age appears to protect individuals from progression to advanced liver disease. Molecular analyses of host immunogenetic elements shows that particular class II human leukocyte associated antigen alleles are associated with clearance of the hepatitis C virus. Additional class II alleles have been identified that are associated with stable viraemia over an extended period of patient follow-up. Although, investigation of large untreated homogeneous cohorts is likely to become more difficult, as the efficacy of anti-viral therapy improves, further investigation of host and viral factors that influence disease progression will help provide an evidence based approach were realistic expectations regarding patient prognosis can be ascertained.

Pregnancy-specific glycoprotein function, conservation and receptor investigation

Pregnancy-specific glycoproteins (PSGs) are highly glycosylated secreted proteins encoded by multi-gene families in some placental mammals. They are carcinoembryonic antigen (CEA) family and immunoglobulin (Ig) superfamily members. PSGs are immunomodulatory, and have been demonstrated to possess antiplatelet and pro-angiogenic properties. Low serum levels of these proteins have been correlated with adverse pregnancy outcomes. Objectives: Main research goals of this thesis were: 1). To attempt to replicate previously reported cytokine responses to PSG-treatment of immune cells and subsequently to investigate functionally important amino acids within PSG1. 2). To determine whether candidate receptor, integrin αvβ3, was a binding partner for PSG1 and to investigate whether PSG1 possessed functionality in a leukocyte-endothelial interaction assay. 3). To determine whether proteins generated from recently identified putative PSG genes in the horse shared functional properties with PSGs from other species. Outcomes: 1). Sequential domain deletion of PSG1 as well as mutation of conserved residues within the PSG1 Ndomain did not affect PSG1-induced TGF-β1. The investigated response was subsequently found to be the result of latent TGF-β1 contaminating the recombinant protein. Protein further purified by SEC to remove this showed no induction of TGF-β1. The most N-terminal glycosylation site was demonstrated to have an important role in PSG N domain secretion. PSG1 attenuated LPS-induced IL-6 and TNF-α. Investigations into signalling underpinning this proved inconclusive. 2). Integrin αvβ3 was identified as a novel PSG1 receptor mediating an as yet unknown function. Preliminary investigations into a role for PSGs as inhibitors of leukocyte endothelial interactions showed no effect by PSG1. 3). Horse PSG protein, CEACAM49, was shown to be similarly contaminated by latent TGF-β1 particle and once removed did not demonstrate TGF-β1 release. Interestingly horse PSG did show anti-platelet properties through inhibition of the plateletfibrinogen interaction as previously published for mouse and human PSGs.