Hepatitis C virus (HCV) is a blood borne human pathogen which is responsible for life long, chronic infection of the liver. The humoral immune response to the virus has not been as intensively studied as the cellular response though antibody has been shown to prevent infection of cells in culture and to prevent spread of HCV in mice with human liver grafts. It is expected that the optimal HCV vaccine will contain both cell mediated immunity and antibody stimulating epitopes. Our aim is to characterise antibodies against HCV elicited by infection that are genotype cross-reactive and infection neutralising in vitro.
Previously we have reported that 98% of a cohort of 100 chronic hepatitis C patients responded by ELISA to g2 (JFH-1) HCV prior to treatment. Analysis by denaturing western blot in a subset of this cohort revealed that each person recognised HCV core antigens but this was not true for the viral envelope glycoprotein, E2, which is the target of many infection neutralising antibody responses. Neutralisation of JFH-1 HCV infection of Huh7 cells in vitro was also commonly amongst the entire cohort irrespective of whether patients were infected with genotype 1, 2, 3 or 4 HCV. The presence of antibody to E2 has been tested by ELISA in a subset of patients using recombinant E2 for genotypes 1, 2, 3 and 4 produced in HEK 293T cells with a plasmid vector system kindly provided by Dr H Drummer. Cross-reactivity of the antibody response between genotypes was common while the strength of the response to E2 was not directly related to the infecting HCV genotype. This information is used to refine the donors of B cells being used to provide epitope information for the capture of immunoglobulin sequences for diagnostic antibodies and vaccine development purposes.