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Sites of vulnerability in HCV E1E2 identified by comprehensive functional screening.

ABSTRACT: The E1 and E2 envelope proteins of hepatitis C virus (HCV) form a heterodimer that drives virus-host membrane fusion. Here, we analyze the role of each amino acid in E1E2 function, expressing 545 individual alanine mutants of E1E2 in human cells, incorporating them into infectious viral pseudoparticles, and testing them against 37 different monoclonal antibodies (MAbs) to ascertain full-length translation, folding, heterodimer assembly, CD81 binding, viral pseudoparticle incorporation, and infectivity. We propose a model describing the role of each critical residue in E1E2 functionality and use it to examine how MAbs neutralize infection by exploiting functionally critical sites of vulnerability on E1E2. Our results suggest that E1E2 is a surprisingly fragile protein complex where even a single alanine mutation at 92% of positions disrupts its function. The amino-acid-level targets identified are highly conserved and functionally critical and can be exploited for improved therapies and vaccines.

SUBMITTER: Pfaff-Kilgore JM

PROVIDER: S-EPMC9281441 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Sites of vulnerability in HCV E1E2 identified by comprehensive functional screening.

Pfaff-Kilgore Jennifer M JM Davidson Edgar E Kadash-Edmondson Kathryn K Hernandez Mayda M Rosenberg Erin E Chambers Ross R Castelli Matteo M Clementi Nicola N Mancini Nicasio N Bailey Justin R JR Crowe James E JE Law Mansun M Doranz Benjamin J BJ

Cell reports 20220501 8

The E1 and E2 envelope proteins of hepatitis C virus (HCV) form a heterodimer that drives virus-host membrane fusion. Here, we analyze the role of each amino acid in E1E2 function, expressing 545 individual alanine mutants of E1E2 in human cells, incorporating them into infectious viral pseudoparticles, and testing them against 37 different monoclonal antibodies (MAbs) to ascertain full-length translation, folding, heterodimer assembly, CD81 binding, viral pseudoparticle incorporation, and infec ...[more]

PMID: 35613596

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Project description:Increasing evidence indicates that broadly neutralizing antibodies (bNAbs) play an important role in immune-mediated control of hepatitis C virus (HCV) infection, but the relative contribution of neutralizing antibodies targeting antigenic sites across the HCV envelope (E1 and E2) proteins is unclear. Here, we isolated thirteen E1E2-specific monoclonal antibodies (MAbs) from B cells of a single HCV-infected individual who cleared one genotype 1a infection and then became persistently infected with a second genotype 1a strain. These MAbs bound six distinct discontinuous antigenic sites on the E1 protein, the E2 protein, or the E1E2 heterodimer. Three antigenic sites, designated AS108, AS112 (an N-terminal E1 site), and AS146, were distinct from previously described antigenic regions (ARs) 1 to 5 and E1 sites. Antibodies targeting four sites (AR3, AR4-5, AS108, and AS146) were broadly neutralizing. These MAbs also displayed distinct patterns of relative neutralizing potency (i.e., neutralization profiles) across a panel of diverse HCV strains, which led to complementary neutralizing breadth when they were tested in combination. Overall, this study demonstrates that HCV bNAb epitopes are not restricted to previously described antigenic sites, expanding the number of sites that could be targeted for vaccine development.IMPORTANCE Worldwide, more than 70 million people are infected with hepatitis C virus (HCV), which is a leading cause of hepatocellular carcinoma and liver transplantation. Despite the development of potent direct acting antivirals (DAAs) for HCV treatment, a vaccine is urgently needed due to the high cost of treatment and the possibility of reinfection after cure. Induction of multiple broadly neutralizing antibodies (bNAbs) that target distinct epitopes on the HCV envelope proteins is one approach to vaccine development. However, antigenic sites targeted by bNAbs in individuals with spontaneous control of HCV have not been fully defined. In this study, we characterize 13 monoclonal antibodies (MAbs) from a single person who cleared an HCV infection without treatment, and we identify 3 new sites targeted by neutralizing antibodies. The sites targeted by these MAbs could inform HCV vaccine development.

Project description:BackgroundIt is unclear whether sites that screen large numbers of patients for Hepatitis C Virus but achieve limited follow-up are more or less effective at having patients succeed through linkage and treatment than lower volume sites that have higher linkage percentages. The objective was to compare the rates of HCV identification, linkage to care, and treatment success between different study sites including the Emergency Department, 3 outpatient clinics with unique patients, and the inpatient setting at one medical center.MethodsThis is a descriptive analysis of 2 years of data from a protocol that integrated HCV screening and treatment into clinical services throughout multiple departments in one medical center. The program used a best practice advisory to prompt testing at all sites, with different triggers for it to fire at each site, and one central navigation program that attempted to link all patients diagnosed with hepatitis C virus to outpatient care. Outcomes included volume of tests performed in each site, Antibody and RNA rates at each site, demographic data, navigation and linkage outcomes, and post-linkage treatment completion.Results28,435 patients were screened across 5 clinical locations. RNA+ rates and absolute numbers linked to MD (linkage rates among all RNA+) were: ED 7.2% RNA+, 224 (22.6%) linked; Inpatient 14.8% RNA+, 27 (17.6%) linked, General Internal Medicine 3.9% RNA+, 269 (65.8%) linked, Infectious Diseases 4.0% RNA+, 34(70.8%) linked, Family Medicine 2.0% RNA+, 28 (75.7%) linked. Demographics, linkage barriers, and treatment initiation rates were different at all sites.ConclusionAmong sites there were differences in the sociodemographic characteristics of patients diagnosed with HCV, as well as differences in the success linking patients to outpatient care. At this medical center, the ED screened the most patients, the inpatient area had the highest RNA positivity rate, the FM clinic had the highest linkage rate, GIM linked the most patients by absolute number, and GIM also had the highest number of patients start treatment.

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Sites of vulnerability in HCV E1E2 identified by comprehensive functional screening.

Publications

Sites of vulnerability in HCV E1E2 identified by comprehensive functional screening.

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