Characterisation of bacterially expressed structural protein E2 of hepatitis C virus

The E2 glycoprotein is a structural component of the hepatitis C virus (HCV) virion. It interacts with putative cellular receptors, elicits production of neutralising antibodies against the virus, and is involved in viral morphogenesis. The protein is considered as a major candidate for anti-HCV vaccine. Despite this, relatively little is known about this protein. Previous studies have focused on the antigenic and functional analysis of the glycosylated forms. This report describes expression of the ectodomain of E2 (recE2) in Escherichia coli cells, its purification, and initial characterisation of its structural and functional properties. It is demonstrated that the purified protein forms small soluble aggregates, which retain functional characteristics of its native counterpart, i.e., it interacts with a putative cellular receptor, CD81, and is recognised by both conformation-dependent and -independent anti-E2 monoclonal antibodies.