Functional analysis of hepatitis C virus E2 glycoproteins and virus-like particles reveals structural dissimilarities between different forms of E2.
Structure-function analysis of the hepatitis C virus (HCV) envelope glycoproteins, E1 and E2, has been difficult due to the unavailability of HCV virions. Truncated soluble forms of E2 have been used as models to study virus interaction with the putative HCV receptor CD81, but they may not fully mimic E2 structures on the virion. Here, we compared the CD81-binding characteristics of truncated E2 (E2(660)) and full-length (FL) E1E2 complex expressed in mammalian cells, and of HCV virus-like particles (VLPs) generated in insect cells. All three glycoprotein forms interacted with human CD81 in an in vitro binding assay, allowing us to test a panel of well-characterized anti-E2 monoclonal antibodies (MAbs) for their ability to inhibit the glycoprotein-CD81 interaction. MAbs specific for E2 amino acid (aa) regions 396-407, 412-423 and 528-535 blocked binding to CD81 of all antigens tested. However, MAbs specific for regions 432-443, 436-443 and 436-447 inhibited the interaction of VLPs, but not of E2(660) or the FL E1E2 complex with CD81, indicating the existence of structural differences amongst the E2 forms. These findings underscore the need to carefully select an appropriate ligand for structure-function analysis.
Owsianka
Ania
A
MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK1.
Clayton
Reginald F
RF
MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK1.
Loomis-Price
Lawrence D
LD
US Military HIV Research Program, Rockville, MD, USA2.
McKeating
Jane A
JA
University of Reading, School of Animal & Microbial Sciences, PO Box 228, Reading, UK3.
Patel
Arvind H
AH
MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK1.
D000818:Animals; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D015703:Antigens, CD / Q000378:metabolism; D016367:Baculoviridae / Q000235:genetics; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D000939:Epitopes / Q000737:chemistry; D005822:Genetic Vectors; D006023:Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016174:Hepacivirus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007313:Insecta; D008565:Membrane Proteins; D011485:Protein Binding; D011991:Receptors, Virus / Q000378:metabolism; D011995:Recombination, Genetic; D060225:Tetraspanin 28; D014162:Transfection; D014616:Vaccinia virus / Q000235:genetics; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000276:immunology
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D015703:Antigens, CD; C554798:CD81 protein, human; D000939:Epitopes; D006023:Glycoproteins; C400562:HVR1 protein, Hepatitis C virus; D008565:Membrane Proteins; D011991:Receptors, Virus; D060225:Tetraspanin 28; D014759:Viral Envelope Proteins; D014764:Viral Proteins