Completion of Hepatitis C Virus Replication Cycle in Heterokaryons Excludes Dominant Restrictions in Human Non-liver and Mouse Liver Cell Lines

Anne Frentzen,Dirk Lindemann,Juliane Gentzsch,Thomas Pietschmann,Florian Zielecki,Martina Friesland,Gert Zimmer,Eike Steinmann,Sibylle Haid,Friedemann Weber,Kathrin Hüging,Julia Bitzegeio,Markus Hoffmann,Charles M Rice

doi:10.1371/journal.ppat.1002029

Abstract

Hepatitis C virus (HCV) is hepatotropic and only infects humans and chimpanzees. Consequently, an immunocompetent small animal model is lacking. The restricted tropism of HCV likely reflects specific host factor requirements. We investigated if dominant restriction factors expressed in non-liver or non-human cell lines inhibit HCV propagation thus rendering these cells non-permissive. To this end we explored if HCV completes its replication cycle in heterokaryons between human liver cell lines and non-permissive cell lines from human non-liver or mouse liver origin. Despite functional viral pattern recognition pathways and responsiveness to interferon, virus production was observed in all fused cells and was only ablated when cells were treated with exogenous interferon. These results exclude that constitutive or virus-induced expression of dominant restriction factors prevents propagation of HCV in these cell types, which has important implications for HCV tissue and species tropism. In turn, these data strongly advocate transgenic approaches of crucial human HCV cofactors to establish an immunocompetent small animal model.

Highlights

Hepatitis C virus (HCV) is an enveloped virus that at present chronically infects about 130 million people worldwide [1]
We investigated if virus-induced or constitutively expressed dominant restriction factors preclude HCV propagation in non-liver tissue and in non-human cells
Using cell fusions between human and mouse cells we show that HCV completes its replication cycle in these heterokaryons

Summary

Introduction

HCV is an enveloped virus that at present chronically infects about 130 million people worldwide [1]. It possesses a positive strand RNA genome of about 9.6 kb composed of non-translated regions (NTRs) at the 59and 39 termini required for translation and RNA replication and a single open reading frame encoding a large polyprotein [2]. One hallmark of HCV is its high degree of sequence variability which likely contributes to its ability to establish chronic infections. The best available treatment, a combination of polyethylene glycol (PEG)-conjugated interferon alpha (IFN-a) and ribavirin, is effective in only a fraction of patients and associated with severe side effects [5].

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