RESUMO
Broadly-neutralizing monoclonal antibodies (bNAbs) may guide vaccine development for highly variable viruses including hepatitis C virus (HCV), since they target conserved viral epitopes that could serve as vaccine antigens. However, HCV resistance to bNAbs could reduce the efficacy of a vaccine. HC33.4 and AR4A are two of the most potent anti-HCV human bNAbs characterized to date, binding to highly conserved epitopes near the amino- and carboxy-terminus of HCV envelope (E2) protein, respectively. Given their distinct epitopes, it was surprising that these bNAbs showed similar neutralization profiles across a panel of natural HCV isolates, suggesting that some viral polymorphisms may confer resistance to both bNAbs. To investigate this resistance, we developed a large, diverse panel of natural HCV envelope variants and a novel computational method to identify bNAb resistance polymorphisms in envelope proteins (E1 and E2). By measuring neutralization of a panel of HCV pseudoparticles by 10 µg/mL of each bNAb, we identified E1E2 variants with resistance to one or both bNAbs, despite 100% conservation of the AR4A binding epitope across the panel. We discovered polymorphisms outside of either binding epitope that modulate resistance to both bNAbs by altering E2 binding to the HCV co-receptor, scavenger receptor B1 (SR-B1). This study is focused on a mode of neutralization escape not addressed by conventional analysis of epitope conservation, highlighting the contribution of extra-epitopic polymorphisms to bNAb resistance and presenting a novel mechanism by which HCV might persist even in the face of an antibody response targeting multiple conserved epitopes.
Assuntos
Anticorpos Neutralizantes/imunologia , Hepacivirus/genética , Anticorpos Anti-Hepatite C/imunologia , Evasão da Resposta Imune/imunologia , Polimorfismo Genético , Receptores Depuradores Classe B/metabolismo , Algoritmos , Sequência de Aminoácidos , Ensaio de Imunoadsorção Enzimática , Hepacivirus/imunologia , Hepacivirus/metabolismo , Hepatite C/imunologia , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Mutagênese Sítio-Dirigida , Testes de Neutralização , Filogenia , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/imunologiaRESUMO
UNLABELLED: Hepatitis C virus (HCV) infection is a global health problem, with millions of chronically infected individuals at risk for cirrhosis and hepatocellular carcinoma. HCV vaccine development is vital in the effort toward disease control and eradication, an undertaking aided by an increased understanding of the mechanisms of resistance to broadly neutralizing antibodies (bNAbs). In this study, we identified HCV codons that vary deep in a phylogenetic tree of HCV sequences and showed that a polymorphism at one of these positions renders Bole1a, a computationally derived, ancestral genotype 1a HCV strain, resistant to neutralization by both polyclonal-HCV-infected plasma and multiple broadly neutralizing monoclonal antibodies with unique binding epitopes. This bNAb resistance mutation reduces replicative fitness, which may explain the persistence of both neutralization-sensitive and neutralization-resistant variants in circulating viral strains. This work identifies an important determinant of bNAb resistance in an ancestral, representative HCV genome, which may inform HCV vaccine development. IMPORTANCE: Worldwide, more than 170 million people are infected with hepatitis C virus (HCV), the leading cause of hepatocellular carcinoma and liver transplantation in the United States. Despite recent significant advances in HCV treatment, a vaccine is needed. Control of the HCV pandemic with drug treatment alone is likely to fail due to limited access to treatment, reinfections in high-risk individuals, and the potential for resistance to direct-acting antivirals (DAAs). Broadly neutralizing antibodies (bNAbs) block infection by diverse HCV variants and therefore serve as a useful guide for vaccine development, but our understanding of resistance to bNAbs is incomplete. In this report, we identify a viral polymorphism conferring resistance to neutralization by both polyclonal plasma and broadly neutralizing monoclonal antibodies, which may inform HCV vaccine development.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Produtos do Gene env/imunologia , Hepacivirus/imunologia , Anticorpos Anti-Hepatite C/imunologia , Polimorfismo Genético , Produtos do Gene env/genética , Hepacivirus/genética , Hepacivirus/fisiologia , Humanos , Evasão da Resposta Imune , Proteínas Mutantes/genética , Proteínas Mutantes/imunologia , Replicação ViralRESUMO
BACKGROUND: Men who have sex with men (MSM) are at high risk for hepatitis B virus (HBV) infection. Data on the effect of highly active antiretroviral therapy (HAART) on incident HBV infection in HIV-infected and HIV-uninfected MSM are limited. OBJECTIVE: To determine predictors of incident HBV infection in MSM during pre-HAART and HAART periods. DESIGN: Observational cohort study. SETTING: Cohort of MSM who have, or are at risk for, HIV infection. PATIENTS: 2375 HBV-uninfected MSM in the Multicenter AIDS Cohort Study. MEASUREMENTS: Poisson regression was used to compare incidence rates of HBV infection in the pre-HAART and HAART eras and to identify factors associated with incidence of HBV infection. RESULTS: In 25,322 person-years of follow-up, 244 incident HBV infections occurred. The unadjusted incidence rate was higher in HIV-infected MSM than in HIV-uninfected MSM (incidence rate ratio [IRR], 1.9 [95% CI, 1.5 to 2.4]) and was significantly lower in the HAART era than in the pre-HAART era among HIV-infected (IRR, 0.2 [CI, 0.1 to 0.4]) and HIV-uninfected (IRR, 0.3 [CI, 0.2 to 0.4]) MSM. Age younger than 40 years (IRR, 2.3 [CI, 1.7 to 3.0]), more than 1 recent sexual partner (IRR, 3.1 [CI, 2.3 to 4.2]), and HIV infection (IRR, 2.4 [CI, 1.8 to 3.1]) were independently associated with higher incidence of HBV infection, whereas HBV vaccination was protective (IRR, 0.3 [CI, 0.2 to 0.4]). Highly active antiretroviral therapy with HIV RNA levels less than 400 copies/mL was associated with protection (IRR, 0.2 [CI, 0.1 to 0.5]), but HAART in those with HIV RNA levels of 400 copies/mL or greater was not. LIMITATION: The observational nature limits inferences about causality. CONCLUSION: Effective HAART is associated with lower incidence of HBV infection; however, even in the HAART era, incidence of HBV infection remains high among MSM. PRIMARY FUNDING SOURCE: National Institute of Allergy and Infectious Diseases.
Assuntos
Terapia Antirretroviral de Alta Atividade , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Hepatite B/epidemiologia , Homossexualidade Masculina/estatística & dados numéricos , Adulto , Estudos de Coortes , Comorbidade , HIV/genética , Infecções por HIV/virologia , Vírus da Hepatite B , Humanos , Incidência , Masculino , RNA Viral/sangue , Fatores de Risco , Parceiros Sexuais , Carga ViralRESUMO
For hepatitis C virus (HCV) and other highly variable viruses, broadly neutralizing mAbs are an important guide for vaccine development. The development of resistance to anti-HCV mAbs is poorly understood, in part due to a lack of neutralization testing against diverse, representative panels of HCV variants. Here, we developed a neutralization panel expressing diverse, naturally occurring HCV envelopes (E1E2s) and used this panel to characterize neutralizing breadth and resistance mechanisms of 18 previously described broadly neutralizing anti-HCV human mAbs. The observed mAb resistance could not be attributed to polymorphisms in E1E2 at known mAb-binding residues. Additionally, hierarchical clustering analysis of neutralization resistance patterns revealed relationships between mAbs that were not predicted by prior epitope mapping, identifying 3 distinct neutralization clusters. Using this clustering analysis and envelope sequence data, we identified polymorphisms in E2 that confer resistance to multiple broadly neutralizing mAbs. These polymorphisms, which are not at mAb contact residues, also conferred resistance to neutralization by plasma from HCV-infected subjects. Together, our method of neutralization clustering with sequence analysis reveals that polymorphisms at noncontact residues may be a major immune evasion mechanism for HCV, facilitating viral persistence and presenting a challenge for HCV vaccine development.