Productive homologous and non-homologous recombination of hepatitis C virus in cell culture

PLoS Pathog. 2013 Mar;9(3):e1003228. doi: 10.1371/journal.ppat.1003228. Epub 2013 Mar 28.

Abstract

Genetic recombination is an important mechanism for increasing diversity of RNA viruses, and constitutes a viral escape mechanism to host immune responses and to treatment with antiviral compounds. Although rare, epidemiologically important hepatitis C virus (HCV) recombinants have been reported. In addition, recombination is an important regulatory mechanism of cytopathogenicity for the related pestiviruses. Here we describe recombination of HCV RNA in cell culture leading to production of infectious virus. Initially, hepatoma cells were co-transfected with a replicating JFH1ΔE1E2 genome (genotype 2a) lacking functional envelope genes and strain J6 (2a), which has functional envelope genes but does not replicate in culture. After an initial decrease in the number of HCV positive cells, infection spread after 13-36 days. Sequencing of recovered viruses revealed non-homologous recombinants with J6 sequence from the 5' end to the NS2-NS3 region followed by JFH1 sequence from Core to the 3' end. These recombinants carried duplicated sequence of up to 2400 nucleotides. HCV replication was not required for recombination, as recombinants were observed in most experiments even when two replication incompetent genomes were co-transfected. Reverse genetic studies verified the viability of representative recombinants. After serial passage, subsequent recombination events reducing or eliminating the duplicated region were observed for some but not all recombinants. Furthermore, we found that inter-genotypic recombination could occur, but at a lower frequency than intra-genotypic recombination. Productive recombination of attenuated HCV genomes depended on expression of all HCV proteins and tolerated duplicated sequence. In general, no strong site specificity was observed. Non-homologous recombination was observed in most cases, while few homologous events were identified. A better understanding of HCV recombination could help identification of natural recombinants and thereby lead to improved therapy. Our findings suggest mechanisms for occurrence of recombinants observed in patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Carcinoma, Hepatocellular / virology
  • Cell Line, Tumor
  • Genome, Viral / genetics
  • Hepacivirus / genetics*
  • Hepacivirus / pathogenicity
  • Hepatocytes / virology*
  • Homologous Recombination*
  • Humans
  • Molecular Sequence Data
  • RNA, Viral / chemistry
  • RNA, Viral / genetics*
  • Sequence Analysis, RNA
  • Transfection
  • Virus Replication

Substances

  • RNA, Viral

Grants and funding

TKHS is supported by a Postdoctoral Fellowship and a Sapere Aude Research Talent award from The Danish Council for Independent Research. AG is the recipient of a Marie Curie International Reintegration Grant. The study was supported by research grants from Lundbeck Foundation (TKHS, AG, JMG and JB), The Danish Cancer Society (YL, JMG and JB), Novo Nordisk Foundation (YL, JMG and JB), The Danish Medical Research Council (YL, JB), A. P. Møller and Chastine Mc-Kinney Møllers Medical Research Foundation (TKHS, JMG and JB), Hvidovre Hospital Research Foundation (TKHS and JMG), Aage Thuesen Bruun and Emmy Katy Bruun's memorial foundation (TKHS) and Leo Nielsen and Karen Margethe Nielsens Foundation for Basic Medical Research (TKHS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.