Mutations That Alter Use of Hepatitis C Virus Cell Entry Factors Mediate Escape From Neutralizing Antibodies

Abstract

BACKGROUND & AIMS The development of vaccines and other strategies to prevent hepatitis C virus (HCV) infection is limited by rapid viral evasion. HCV entry is the first step of infection; this process involves several viral and host factors and is targeted by host-neutralizing responses. Although the roles of host factors in HCV entry have been well characterized, their involvement in evasion of immune responses is poorly understood. We used acute infection of liver graft as a model to investigate the molecular mechanisms of viral evasion. METHODS We studied factors that contribute to evasion of host immune responses using patient-derived antibodies, HCV pseudoparticles, and cell culture–derived HCV that express viral envelopes from patients who have undergone liver transplantation. These viruses were used to infect hepatoma cell lines that express different levels of HCV entry factors. RESULTS By using reverse genetic analyses, we identified altered use of host-cell entry factors as a mechanism by which HCV evades host immune responses. Mutations that alter use of the CD81 receptor also allowed the virus to escape neutralizing antibodies. Kinetic studies showed that these mutations affect virus–antibody interactions during postbinding steps of the HCV entry process. Functional studies with a large panel of patient-derived antibodies showed that this mechanism mediates viral escape, leading to persistent infection in general. CONCLUSIONS We identified a mechanism by which HCV evades host immune responses, in which use of cell entry factors evolves with escape from neutralizing antibodies. These findings advance our understanding of the pathogenesis of HCV infection and might be used to develop antiviral strategies and vaccines.

Hepatitis C virus resistance to broadly neutralizing antibodies measured using replication-competent virus and pseudoparticles

“…Our work supports prior more limited studies showing that HCVcc and HCVpp with identical E1E2 have similar relative neutralization resistance (Bailey et al, 2015a;Fofana et al, 2012;Swann et al, 2016;Urbanowicz et al, 2015). Importantly, to our knowledge, this is the first study to show this correlation using a diverse panel of human bNAbs targeting distinct epitopes across E1E2 and a large panel of diverse natural E1E2 variants, suggesting that these results are broadly applicable to other E1E2 variants and other antibodies.…”

“…Neutralization results obtained using HCVcc and HCVpp have generally been similar (Fofana et al, 2012;Meunier et al, 2005;Scheel et al, 2008;Swann et al, 2016;Urbanowicz et al, 2015), but comparisons of specific infectivity and neutralization of HCVpp and HCVcc expressing genetically identical E1E2 variants have previously been performed only on a fairly limited basis, and to our knowledge neutralization of E1E2-matched HCVpp and HCVcc has never been compared using a diverse panel of bNAbs targeting distinct epitopes.…”

Apolipoprotein E Mediates Evasion From Hepatitis C Virus Neutralizing Antibodies

“…Clearly, the development of an effective vaccine requires a detailed understanding of viral evasion from host immune responses, including nAbs. Previous studies investigating the molecular mechanisms of HCV liver graft infection, identified a viral variant termed VL 5,6 with efficient escape from patient nAbs. 5,6 Functional genetics had identified phenylalanine at HCV polyprotein residue 447 as being important for neutralization escape.…”

“…Previous studies investigating the molecular mechanisms of HCV liver graft infection, identified a viral variant termed VL 5,6 with efficient escape from patient nAbs. 5,6 Functional genetics had identified phenylalanine at HCV polyprotein residue 447 as being important for neutralization escape. 6 This amino acid is widely conserved among HCV isolates, as shown by its prevalence of 98.4% in all genotypes (including Jc1, Japanese fulminant hepatitis virus [JFH1], and H77) and 96.2% in genotype 1b strains (including VL).…”

“…5,6 Functional genetics had identified phenylalanine at HCV polyprotein residue 447 as being important for neutralization escape. 6 This amino acid is widely conserved among HCV isolates, as shown by its prevalence of 98.4% in all genotypes (including Jc1, Japanese fulminant hepatitis virus [JFH1], and H77) and 96.2% in genotype 1b strains (including VL). 6 In addition, previous studies had shown that replacement of phenylalanine by leucine (F447L) rendered HCV highly susceptible to neutralization.…”