Neutralization resistance of hepatitis C virus can be overcome by recombinant human monoclonal antibodies

Abstract

Immunotherapy and vaccine development for hepatitis C virus (HCV) will depend on broadly reactive neutralizing antibodies. However, studies in infectious JFH1-based culture systems expressing patient derived Core-NS2 proteins have suggested neutralization resistance for specific HCV strains, in particular of genotype 2. To further examine this phenomenon, we developed a panel of HCV genotype 2 recombinants for testing of sensitivity to neutralization by chronic-phase patient sera and lead human monoclonal antibodies. The novel Core-NS2 recombinants, with patient derived genotype 2a (strain T9), 2b (strains DH8 and DH10), and 2c (strain S83) consensus sequences, were viable in Huh7.5 hepatoma cells without requirement for adaptive mutations, reaching HCV infectivity titers of 3.9–4.5 log10 focus-forming units per mL. In in vitro neutralization assays, we demonstrated that the novel genotype 2 viruses as well as prototype strains J6(2a) and J8(2b), all with authentic envelope proteins, were resistant to neutralization by genotype 2a, 2b, 2c, 2j, 2i, and 2q patient sera. These patient sera, however, had high titers of HCV-specific neutralizing antibodies, since they efficiently reduced the infectivity of J6(2a) and J8(2b) with deleted hypervariable region 1. The genotype 2a, 2b, and 2c viruses, found resistant to polyclonal patient sera neutralization, were efficiently neutralized by two lead human monoclonal antibodies, AR4A and HC84.26. Conclusion: Using novel 2a, 2b, and 2c cell culture systems, expressing authentic envelope proteins, we demonstrated resistance of HCV to patient-derived polyclonal high-titer neutralizing antibodies. However, the same genotype 2 culture viruses were all sensitive to human monoclonal HCV antibodies recognizing conformational epitopes, indicating that neutralization resistance of HCV can be overcome by applying recombinant antibodies. These findings have important implications for HCV immunotherapy and vaccine development.

Multiplexed screening of natural humoral immunity identifies antibodies at fine specificity for complex and dynamic viral targets

“…1 For example, accessing the functional successes of in vivo humoral immune system defenses, which have evolved side-by-side with dynamic infectious agents, has allowed the cloning of broadly neutralizing antibodies to complex infectious diseases using a variety of approaches. [2][3][4][5][6][7] A fascinating trend is the discovery of specific Ig germline usage among unrelated and geographically disperse individuals against specific viral antigens. 3,8 A parental germline sequence has not generally been anti-viral, but rather provides the best possible scaffold for the development of an affinity-matured, efficacious monoclonal antibody (mAb).…”

Adaptive Mutations Enhance Assembly and Cell-to-Cell Transmission of a High-Titer Hepatitis C Virus Genotype 5a Core-NS2 JFH1-Based Recombinant

“…Subsequently, several different types of intra-and intergenotypic JFH1-based recombinant culture systems, as well as full-length cultures of other strains, have been developed (13)(14)(15)(16)(17), with Core-NS2 and NS5A infection cultures available for all 7 major HCV genotypes (18)(19)(20). Introduction of adaptive mutations has been necessary for efficient propagation of most HCVcc recombinants (18,19,(21)(22)(23)(24)(25)(26), except JFH1-based 5= untranslated region (UTR)-NS2 or Core-NS2 genotype 2 recombinants (11,18,21,23,27,28). Although these systems have advanced HCV research, they produce insufficient amounts of virus particles for morphological or vaccine studies, highlighting the need for improved culture systems.…”

Immunoglobulin with High-Titer In Vitro Cross-Neutralizing Hepatitis C Virus Antibodies Passively Protects Chimpanzees from Homologous, but Not Heterologous, Challenge

“…During chronic infection, HCV persists despite the presence of high-titer NAbs, perhaps because it is shielded from neutralization (47)(48)(49)(50) or neutralization-resistant mutants are continuously developing (22,23,51). It was demonstrated in vitro that chronic-phase patient H sera neutralized only variants from time points early in infection, not later variants (22).…”

“…However, the lack of protection against heterologous strains highlights significant issues regarding the possibility of developing broadly protective immunoglobulin preparations using patient-derived antibodies alone. More likely, efficient neutralization will require monoclonal antibodies against conserved conformational epitopes and/or combinations of antibodies targeting different HCV epitopes or viral variants (44,50,(52)(53)(54).…”