Essay On Hepatitis C
These nonstructural proteins are necessary for viral propagation and have been the targets for newer antiviral therapies, such as the direct-acting antiviral agents (DAAs).
NS2/3 and NS3/4A are proteases responsible for cleaving the HCV polyprotein.
Most patients with acute and chronic infection are asymptomatic.
Patients and healthcare providers may detect no indications of these conditions for long periods; however, chronic hepatitis C infection and chronic active hepatitis are slowly progressive diseases and result in severe morbidity in 20-30% of infected persons.
The major HCV genotype worldwide is genotype 1, which accounts for 40%-80% of all isolates.
Genotype details are as follows: Transfusion of blood contaminated with hepatitis C virus (HCV) was once a leading means of HCV transmission.Cirrhosis develops in 20-50% of patients with chronic hepatitis C infection.Liver failure and HCC (11%-19%) can eventually result.Two regions of the E2 protein, designated hypervariable regions 1 and 2, have an extremely high rate of mutation, believed to result from selective pressure by virus-specific antibodies.The envelope protein E2 also contains the binding site for CD-81, a tetraspanin receptor expressed on hepatocytes and B lymphocytes that acts as a receptor or coreceptor for HCV.Almost 75% of HCV deaths occurred among adults between the ages of 45 and 64 years.Because most patients infected with HCV have chronic liver disease, which can progress to cirrhosis and HCC, chronic infection with HCV is one of the most important causes of chronic liver disease (see the image below) and, according to a report by Davis et al, the most common indication for orthotopic liver transplantation (OLT) in the United States.The HCV genome consists of a single, open reading frame and two untranslated, highly conserved regions, 5'-UTR and 3'-UTR, at both ends of the genome.The genome has approximately 9500 base pairs and encodes a single polyprotein of 3011 amino acids that are processed into 10 structural and regulatory proteins (see the image below).HCV core protein is an important risk factor in the development of liver disease; it can modulate several signaling pathways affecting cell cycle regulation, cell growth promotion, cell proliferation, apoptosis, oxidative stress, and lipid metabolism.Other viral components are nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A, NS5B, and p7), whose proteins function as helicase-, protease-, and RNA-dependent RNA polymerase, although the exact function of p7 is unknown.