Junctional and somatic hypermutation-induced CX4C motif is critical for the recognition of a highly conserved epitope on HCV E2 by a human broadly neutralizing antibody

Induction of broadly neutralizing monoclonal antibodies(bNAbs)that bind to the viral envelope glycoproteins is a major goal of hepatitis C virus(HCV)vaccine research.The study of bNAbs arising in natural infection is essential in this endeavor.We generated a human antibody,8D6,recognizing the E2 protein of HCV isolated from a chronic hepatitis C patient.This antibody shows broadly neutralizing activity,which covers a pan-genotypic panel of cell culture-derived HCV virions(HCVcc).Functional and epitope analyses demonstrated that 8D6 can block the interaction between E2 and CD81 by targeting a highly conserved epitope on E2.We describe how the 8D6 lineage evolved via somatic hypermutation to achieve broad neutralization.We found that the V(D)J recombination-generated junctional and somatic hypermutation-induced disulfide bridge(C-C)motif in the CDRH3 is critical for the broad neutralization and binding activity of 8D6.This motif is conserved among a series of broadly neutralizing HCV antibodies,indicating a common binding model.Next,the 8D6 inferred germline(iGL)was reconstructed and tested for its binding affinity and neutralization activity.Interestingly,8D6 iGL-mediated relatively strong inhibition of the 1b genotype PR79L9 strain,suggesting that PR79L9 may serve as a potential natural viral strain that provides E2 sequences that induce bNAbs.Overall,our detailed epitope mapping and genetic studies of the HCV E2-specific mAb 8D6 have allowed for further refinement of antigenic sites on E2 and reveal a new mechanism to generate a functional CDRH3,while its iGL can serve as a probe to identify potential HCV vaccine strains.

Prevalence and Severity of HBV-Associated Acute-on-Chronic Liver Failure Due to Irregular Medication of Nucleos(t)ide Analogs

Hepatitis B virus(HBV)represents the commonest etiologic agent of acute-on-chronic liver failure(ACLF)in most Asian countries.Nucleos(t)ide analogs(NAs)are effective in the treatment of chronic HBV infections,but may also exacerbate the disease and stimulate its development into HBV-associated ACLF if not used appropriately.The current study aimed to assess the prevalence and severity of HBV-associated ACLF as a result from irregular medication of NAs(IMNA).A total of 1134 individuals with HBV-associated ACLF in nine hospitals in Heilongjiang Province were enrolled in this study between 2005 and 2015.Among these,777 chronic hepatitis B(CHB)and 357 HBV-associated liver cirrhosis cases were classified based on various predisposing factors,including IMNA,HBV reactivation(HBVR),infections,treatment drugs,alcohol use and others(hepatitis C virus,hepatitis E virus,gastrointestinal bleeding and unknown reasons).The percentage and improvement rate were examined.Among individuals with HBV-associated ACLF and CHB,IMNA was found in 9.01%,HBVR in 46.20%,infections in 9.52%,treatment drugs in 14.67%,alcohol in 11.71%,and others in 24.58%as predisposing factors.Improvement rates in cases with IMNA,HBVR,infections,treatment drugs,alcohol and others were 41.43%,58.50%,58.11%,56.14%,53.85%,and 65.97%,respectively.Multivariable analysis showed that IMNA,others,infections,hepatic encephalopathy and hepatorenal syndrome were associated with prognosis.Only IMNA independently predicted HBV-associated ACLF prognosis.Overall,our study demonstrated that the percentage of IMNAinduced HBV-associated ACLF was 12.61%,and worse disease conditions resulted from IMNA compared with other factors.Thus,the suitability of treatment with NAs should be thoroughly evaluated.