Characterization of modified hepatitis C virus E2 proteins expressed on the cell surface.
The envelope proteins of hepatitis C virus (HCV) are the likely targets of neutralizing antibodies and their molecular and functional characterization is relevant for vaccine development. We previously showed that surface-expressed E2 is a better immunogen than intracellular E2 and, therefore, we were interested in exploring more efficient ways to present E2 protein on the cell surface. We found that E2 targeted to the cell surface by replacement of its transmembrane domain did not bring E1 to the surface although E1 could be expressed independently on the cell surface if its transmembrane domain was similarly replaced. FACS analysis suggested that E2 expressed on the cell surface acquired its native conformation more efficiently when truncated at aa 661 than when truncated at aa 715. The shorter form of truncated E2 better retained the ability to bind the second extracellular loop (EC2) of CD81, the putative HCV receptor. Interestingly, deletion of the hypervariable region 1 (HVR1) did not perceptibly alter E2 structure; cell-surface forms of E2 lacking the HVR1 remained reactive with conformation-sensitive MAbs and were able to bind recombinant EC2 of CD81.
Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. XFORNS@clinic.ub.es
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D000596:Amino Acids; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D015870:Gene Expression; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D016296:Mutagenesis; D011485:Protein Binding; D011487:Protein Conformation; D011817:Rabbits; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D060225:Tetraspanin 28; D014407:Tumor Cells, Cultured; D014759:Viral Envelope Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
D000596:Amino Acids; D015703:Antigens, CD; C554798:CD81 protein, human; C554799:Cd81 protein, mouse; C087035:E1 protein, Hepatitis C virus; C400562:HVR1 protein, Hepatitis C virus; D008565:Membrane Proteins; D011991:Receptors, Virus; D011993:Recombinant Fusion Proteins; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C091015:glycoprotein E2, Hepatitis C virus