Expression and purification of the hepatitis C virus core protein in Ecoli and testing of human sera with this core antigen

Abstract

The hepatitis C virus (HCV) infection is an important cause of morbidity and mortality world wide. Infection with HCV becomes chronic in more than 80% of the cases and it accounts for 20%of all cases of acute hepatitis. Hepatitis C virus was first identified by the molecular cloning of the virus genome in 1989. It is an enveloped, positive strand RNA virus with a genome size of around 9.5 Idlobases. The single stranded RNA genome of the virus contains a large open reading frame codes for a large poly-protein of 3,010 to 3,033 amino acids which is shown to be processed by a combination of host and viral proteinases to produce at least ten proteins post-translationally. The proteins that are closer to the amino terminal of the poly-protein are termed as structural and the rest closer to the carboxy terminal are called non-structural (NS) proteins. The core protein is the putative nucleocapsid component of the virion, and it is highly basic in nature. Core protein is the most highly conserved region of the hepatitis C virus open reading frame and it is shown to be highly immunogenic. Also, as the core protein is the putative capsid protein of the hepatitis C virus, antibodies against core antigen most probably arise much earlier than the antibodies against nonstructural proteins. In this study, the core protein of the hepatitis C virus was cloned, expressed and purified in order to establish an ELISA system to test the human sera with this viral antigen. It was shown that in 86% of the patients, diagnosed previously with the third generation enzyme immunoassays to be infected with hepatitis C, have antibodies against this core antigen. The core antigen gave no false positive results when tested with the negative control samples which were found to be Anti-HCV negative previously.