Adaptive mutations allow establishment of JFH1-based cell culture systems for hepatitis C virus genotype 4A

摘要

The present inventors developed three 4a/2a intergenotypic recombinants in which the JFH1 structural genes (Core, E1 and E2), p7 and all of or part of NS2 were replaced by the corresponding genes of the genotype 4a reference strain ED43. The 4a/2a junction in NS2 was placed after the first transmembrane domain (α), in the cytoplasmic part (β) or at the NS2/NS3 cleavage site (y). Following transfection of Huh7.5 cells with RNA transcripts, infectious viruses were produced in the ED43/JFH1-β and -y cultures only. Compared to the 2a control virus, production of infectious viruses was significantly delayed. However, in subsequent passages efficient spread of infection and high HCV RNA titers were obtained. Infectivity titers were approximately 10-fold lower than for the 2a control virus. Sequence analysis of recovered 4a/2a recombinants from 3 serial passages and subsequent reverse genetic studies revealed a vital dependence on a mutation in the NS2 4a part. ED43/JFH1-γ further depended on a second NS2 mutation. Infectivity of the 4a/2a viruses was CD81 dependent. Conclusion: The developed 4a/2a viruses provide a robust in vitro tool for research in HCV genotype 4, including vaccine studies and functional analyses of an increasingly important genotype in the Middle East and Europe.