Poly(rC)-Binding Protein 1 Limits Hepatitis C Virus Virion Assembly and Secretion.

Sophie E Cousineau,Selena M Sagan,Marylin Rheault

doi:10.3390/v14020291

Abstract

The hepatitis C virus (HCV) co-opts numerous cellular elements, including proteins, lipids, and microRNAs, to complete its viral life cycle. The cellular RNA-binding protein, poly(rC)-binding protein 1 (PCBP1), was previously reported to bind to the 5′ untranslated region (UTR) of the HCV genome; however, its importance in the viral life cycle has remained unclear. Herein, we sought to clarify the role of PCBP1 in the HCV life cycle. Using the HCV cell culture (HCVcc) system, we found that knockdown of endogenous PCBP1 resulted in an overall decrease in viral RNA accumulation, yet resulted in an increase in extracellular viral titers. To dissect PCBP1’s specific role in the HCV life cycle, we carried out assays for viral entry, translation, genome stability, RNA replication, as well as virion assembly and secretion. We found that PCBP1 knockdown did not directly affect viral entry, translation, RNA stability, or RNA replication, but resulted in an overall increase in infectious particle secretion. This increase in virion secretion was evident even when viral RNA synthesis was inhibited, and blocking virus secretion could partially restore the viral RNA accumulation decreased by PCBP1 knockdown. We therefore propose a model where endogenous PCBP1 normally limits virion assembly and secretion, which increases viral RNA accumulation in infected cells by preventing the departure of viral genomes packaged into virions. Overall, our findings improve our understanding of how cellular RNA-binding proteins influence viral genomic RNA utilization during the HCV life cycle.

Highlights

Previous reports suggested that the poly(rC)-binding protein 1 (PCBP1) protein directly interacted with the 50 untranslated regions (UTR)
We assessed how PCBP1 knockdown affected the accumulation of HCV cell culture (HCVcc) using two viral strains: the cell culture-adapted JFH-1T strain, and the chimeric J6/JFH-1 strain (Figure 1A) [17,18]
We found that knocking down endogenous PCBP1 decreased viral protein expression and Hepatitis C virus (HCV) RNA accumulation of both strains, resulting in an approximately 2.2-fold and 3.3fold decrease in JFH-1T and J6/JFH-1 viral RNA accumulation, respectively (Figure 1B–D)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Hepatitis C virus (HCV) is an enveloped virus of the Flaviviridae family (genus: hepacivirus) that typically causes a persistent liver infection [1]. Its ~9.6 kb single-stranded, positive-sense RNA genome contains a single open reading frame flanked by 50 and 30 untranslated regions (UTR). A highly structured internal ribosomal entry site (IRES) in the

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Conclusion