Year: 2011
Type: dissertation
Abstract: Hepatitis C virus (HCV) is a small RNA encoded virus that causes acute and chronic infections of the liver and is associated with fibrosis, cirrhosis, hepatocellular carcinoma and end-stage liver disease.The infection is linked with elevated serum ferritin levels and iron deposits within the liver which are associated with an increased risk of progression of HCV disease.It is hypothesised firstly that the presence of excess iron affects HCV replication and secondly that iron homeostasis is altered by HCV replication.The main aim of this study was to investigate the influence of iron on HCV replication by analysing the spread of infection and the titre of infectious HCV produced in the presence of excess iron.The second aim was to determine if HCV infection itself alters the level of iron stored as ferritin in liver cells.HCV Japanese fulminant hepatitis (JFH-1) infection of the human hepatoma cell line, (Huh7), was used as the model for this study.The culture conditions were first optimised to allow detection of ferritin by western blot.Huh7 cells were then treated with iron provided by 5, 10 or 20 μg/ml ferric ammonium citrate (FAC) prior to HCV infection (0.001 MOI).No evidence of inhibition of HCV replication was found on day 7 post infection (PI) by analysis of the level of viral protein detected by western blot, the proportion of infected cells determined by immunohistochemistry and flow cytometry or the titre of infectious HCV produced.A comparison of iron donors was then undertaken and conditions were changed to add iron donors 1 day after HCV.Viral RNA levels were not significantly reduced on treatment with 20 μg/ml FAC and 25 μM holo-transferrin and assays for viral protein and production of infectious virus again showed no evidence of inhibition.Fe-PIH, a lipophilic iron donor, had the greatest effect, reducing both the proportion of infected cells and the titre of infectious virus produced.When the reduction UTR untranslated regions ZIP14 Zrt-and Irt-like proteins 14Chapter 1 contains 9099 nucleotides (Zein, 2000).The genotype affects the success of certain treatments; standard treatment is least effective against genotype 1 (Schlutter, 2011).The distribution of genotypes worldwide varies (Figure 1.1) (Gravitz, 2011); genotype 1 is widespread while others such as genotypes 10 and 11, which are only found in Indonesia, are localised to specific areas (Schlutter, 2011;Zein, 2000).Genotype 1 is predominant in 1.1.4.2 Developing treatments As the current standard treatment of HCV is least effective with the predominant genotype 1, other drugs are being developed to target this problem; such as Boceprevir and Telaprevir (Gravitz, 2011).Boceprevir from Merck and Telaprevir from Vertex Pharmaceuticals are currently in phase III trials.Both are direct-acting antivirals that target HCV directly.The drugs are protease inhibitors that block the HCV NS3/4A humans, chimpanzees and Tupaia belangeri, targeting hepatocytes (Dolgin, 2011).Glycoproteins E1 and E2 of the HCV surface bind to cell receptors of the host to gain entry into the cell.Accepted target receptors include the tetraspanin protein CD81, low density lipoprotein receptor, scavenger receptor class B type I and claudin-1 (Asselah and Marcellin, 2011; Moradpour, Penin, and Rice, 2007).which attenuates interferon stimulated genes that inhibit HCV replication (Gale and Foy, 2005).HCV directly inhibits natural killer cells and dendritic cells (Castello et al., 2010;Eisenstein, 2011).Activation and function of natural killer cells are impaired by HCV envelope proteins, resulting in natural killer cell anergy or exhaustion (Mondelli, Varchetta, and Oliviero, 2010).Viral antigen presentation by dendritic cells is impaired,
Author: Hayley Clark
Language: English
Topic: Hepatitis C virus research
Subfield: Hepatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funder: Murdoch University
OpenAlex ID: W1534012911