Hepatitis C virus enters liver cells using the CD81 receptor complex proteins calpain-5 and CBLB.

Janina Bruening,Felix Meissner,Lars Kaderali,Carine Marinach,Thomas Pietschmann,Lisa Lasswitz,Sina Kahl,Florian W Vondran,Gisa Gerold,Olivier Silvie,Pia Banse

doi:10.1371/journal.ppat.1007111

Abstract

Hepatitis C virus (HCV) and the malaria parasite Plasmodium use the membrane protein CD81 to invade human liver cells. Here we mapped 33 host protein interactions of CD81 in primary human liver and hepatoma cells using high-resolution quantitative proteomics. In the CD81 protein network, we identified five proteins which are HCV entry factors or facilitators including epidermal growth factor receptor (EGFR). Notably, we discovered calpain-5 (CAPN5) and the ubiquitin ligase Casitas B-lineage lymphoma proto-oncogene B (CBLB) to form a complex with CD81 and support HCV entry. CAPN5 and CBLB were required for a post-binding and pre-replication step in the HCV life cycle. Knockout of CAPN5 and CBLB reduced susceptibility to all tested HCV genotypes, but not to other enveloped viruses such as vesicular stomatitis virus and human coronavirus. Furthermore, Plasmodium sporozoites relied on a distinct set of CD81 interaction partners for liver cell entry. Our findings reveal a comprehensive CD81 network in human liver cells and show that HCV and Plasmodium highjack selective CD81 interactions, including CAPN5 and CBLB for HCV, to invade cells.

Highlights

The liver is the site of initial replication of diverse parenterally transmitted pathogens
CD81 is a cell membrane protein, which functions as entry factor for hepatitis C virus (HCV) and malaria sporozoites in the human liver. It remains enigmatic how CD81 guides the entry process of both pathogens and whether it functions in a similar way during liver cell invasion of Hepatitis C virus (HCV) and malaria parasites
Mass spectrometry based-proteomics has matured into a powerful technology to comprehensively analyze protein-protein interactions (PPIs) from cell culture and primary cell material [22,23,24]

Summary

Introduction

The liver is the site of initial replication of diverse parenterally transmitted pathogens. While HCV binds to the ectodomain of CD81 and co-internalizes with CD81 into clathrin-coated vesicles [5,7], P. falciparum and the murine parasite P. yoelii do not seem to directly interact with CD81, but still require CD81 for productive uptake into hepatocytes [4,8]. The viral nucleocapsid disassembles and releases the viral genome to the cytoplasmic sites of viral genome translation and replication. This uncoating and trafficking is thought to require serum response factor binding protein 1 (SRFBP1), which is recruited to CD81 during HCV entry [19]. CD81 fulfills multiple functions during HCV entry [20], the steady-state CD81 interaction partners required for HCV entry are largely unknown and demand elucidation

Methods

Results

Discussion

Conclusion