Abstract
Sequence variation in the envelope E1 and E2 glycoproteins of hepatitis C virus (HCV) could account for differences in disease pathogenesis in patients infected with different genotypes. A cDNA encoding the structural region of the hepatitis C polyprotein was constructed to match the majority sequence of viral RNA extracted from a patient infected with genotype 3a (designated strain HCV3aβGla). The principal differences predicted between E2 of HCV3aβGla and the corresponding H77c genotype 1a protein were that the former contained six more amino acids (361 vs. 355), but it had one fewer glycosylation site. Expression studies showed that, in common with the H77c glycoproteins, E1 and E2 from HCV3aβGla localised to the endoplasmic reticulum (ER) membrane in both Huhβ7 and BHK tissue culture cells and interacted to form native complexes. Analysis of the crossβreactivity of antibodies raised against glycoproteins of genotype 1a strains showed that three of five monoclonal antibodies that recognise linear epitopes were able to detect E2 from strain HCV3aβGla. However, neither conformational E2 antibodies nor antibodies raised against E1 were able to detect the HCV3aβGla glycoproteins. In receptor binding assays, E2 of HCV3aβGla consistently failed to bind CD81, a putative cell receptor for HCV. Absence of binding to CD81 and lack of recognition by most antibodies raised to genotype 1a glycoproteins indicate important differences between these glycoproteins representative of genotypes 3a and 1a. These may be pertinent to the differences in response to interferon therapy and the prevalence of steatosis reported in patients infected with these genotypes. J. Med. Virol. 70:361β372, 2003. Β© 2003 WileyβLiss, Inc.