Hepatitis C virus (HCV) E1 and E2 protein regions that specifically bind to HepG2 cells

Background/Aims: Identify hepatitis C virus (HCV) sequences in El and E2 protein binding to HepG2. Methods: Synthetic 20-mer long, ten-residue overlapped peptides, from El and E2 proteins, were tested in HepG2 or Raji cell-binding assays. Affinity constants, binding site number per cell and Hill coefficients were determined by saturation assay for high activity binding peptides (HABPs). Receptors for HepG2 cell were determined by cross-linking and sodium dodecyl sulfate-polyacrylamide get electrophoresis analysis. Results: Twelve HABPs were found in HCV genotype la, allowing six hepatocyte-binding sequences (HBSs) to be defined: two peptide-binding regions in El HABPs 4913 (YQVRNSTGLYHVTNDCPNSS) and 4918 (MTPTVATRDGKLPATQLRRHY). Four hepatocyte-binding regions were defined in E2: region-I, peptide 4931 (ETHVTGGSAGHTVSGFVSLLY); region-H, 4937-4939 (HHKFNSSGCPERLASCRPLTDFDQGWGPISYANGSGPDQR); region-III, 4943-4945 (PVYCFTPSPVVVGTTDRSGAPTYSWGENDTDVFVLNNTR) and region-IV, 4949-4952 (CGAPPCVIGGAGNNTLHCPTDCFRKHPDATYSRCGSGPWITPRCLVDYPY). The underlined sequences are most relevant in the binding process. HABPs 4913 and 4938 also bind to CD81 positive Raji cells. Region-H 4938 HABPs bind to 50 and 60 kDa HepG2 cell membrane surface proteins. Conclusions: Six HVRs to the HepG2 were identified. Some HABPs have been previously found to be antigenic and immunogenic. HABPs, 4918 (from El), 4938, 4949,4950,4951 and 4952 (from E2) have not been previously recognised. These HABPs could be relevant to HCV invasion of hepatocytes. (C) 2002 Published by Elsevier Science B.V. on behalf of the European Association for the Study of the Liver.