title: Mapping a region of hepatitis C virus E2 that is responsible for escape from neutralizing antibodies and a core CD81-binding region that does not tolerate neutralization escape mutations.
abstract: Understanding the interaction between broadly neutralizing antibodies and their epitopes provides a basis for the rational design of a preventive hepatitis C virus (HCV) vaccine. CBH-2, HC-11, and HC-1 are representatives of antibodies to overlapping epitopes on E2 that mediate neutralization by blocking virus binding to CD81. To obtain insights into escape mechanisms, infectious cell culture virus, 2a HCVcc, was propagated under increasing concentrations of a neutralizing antibody to isolate escape mutants. Three escape patterns were observed with these antibodies. First, CBH-2 escape mutants that contained mutations at D431G or A439E, which did not compromise viral fitness, were isolated. Second, under the selective pressure of HC-11, escape mutations progressed from a single L438F substitution at a low antibody concentration to double substitutions, L438F and N434D or L438F and T435A, at higher antibody concentrations. Escape from HC-11 was associated with a loss of viral fitness. An HCV pseudoparticle (HCVpp) containing the L438F mutation bound to CD81 half as efficiently as did wild-type (wt) HCVpp. Third, for HC-1, the antibody at a critical concentration completely suppressed viral replication and generated no escape mutants. Epitope mapping revealed contact residues for CBH-2 and HC-11 in two regions of the E2 glycoprotein, amino acids (aa) 425 to 443 and aa 529 to 535. Interestingly, contact residues for HC-1 were identified only in the region encompassing aa 529 to 535 and not in aa 425 to 443. Taken together, these findings point to a region of variability, aa 425 to 443, that is responsible primarily for viral escape from neutralization, with or without compromising viral fitness. Moreover, the region aa 529 to 535 is a core CD81 binding region that does not tolerate neutralization escape mutations.
authors.affiliation: Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Zhen-Yong
authors.initials: ZY
authors.lastname: Keck
authors.forename: Anasuya
authors.initials: A
authors.lastname: Saha
authors.forename: Jinming
authors.initials: J
authors.lastname: Xia
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Patrick
authors.initials: P
authors.lastname: Lau
authors.forename: Thomas
authors.initials: T
authors.lastname: Krey
authors.forename: Felix A
authors.initials: FA
authors.lastname: Rey
authors.forename: Steven K H
authors.initials: SK
authors.lastname: Foung
mesh_terms: D019943:Amino Acid Substitution; D057134:Antibodies, Neutralizing / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology*; D018604:Epitope Mapping; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D016174:Hepacivirus / Q000235:genetics / Q000254:growth & development / Q000276:immunology*; D006801:Humans; D020125:Mutation, Missense; D011485:Protein Binding; D014758:Viral Core Proteins / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D000939:Epitopes; D014758:Viral Core Proteins; D014759:Viral Envelope Proteins; C069130:nucleocapsid protein, Hepatitis C virus; C091015:glycoprotein E2, Hepatitis C virus