CD81 Receptor Regions outside the Large Extracellular Loop Determine Hepatitis C Virus Entry into Hepatoma Cells

• Published in: Viruses Vol. 10; no. 4; p. 207
• Main Authors: Banse, Pia, Moeller, Rebecca, Bruening, Janina, Lasswitz, Lisa, Kahl, Sina, Khan, Abdul G, Marcotrigiano, Joseph, Pietschmann, Thomas, Gerold, Gisa
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 20.04.2018; MDPI
• Subjects: Amino Acid Sequence; Animals; CD81; CD81 antigen; Cell culture; Cell Line; Chimeras; Cholesterol; cholesterol-binding residue; Glycoproteins; HCV; Hepacivirus - pathogenicity; Hepacivirus - physiology; Hepatitis C; hepatitis C virus; Hepatocytes; Hepatocytes - virology; Hepatoma; Homology; Humans; Infections; Infectivity; Insects; Intracellular; Lipids; Liver cancer; Mutation; Phenotypes; Protein Binding; Protein Domains; Proteins; receptor; Receptors, Virus - chemistry; Receptors, Virus - genetics; Receptors, Virus - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; Susceptibility; susceptibility-determining domains; tetraspanin; Tetraspanin 28 - chemistry; Tetraspanin 28 - genetics; Tetraspanin 28 - metabolism; transmembrane domain four; Transmembrane domains; Tumor Cells, Cultured; Viral Envelope Proteins - metabolism; Virus Internalization; Viruses; St Louis Missouri; United States > US; chimeras; susceptibility-determining domains; receptor; CD81; tetraspanin; hepatitis C virus; transmembrane domain four; HCV; cholesterol-binding residue
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v10040207

Hepatitis C virus (HCV) enters human hepatocytes using four essential entry factors, one of which is human CD81 (hCD81). The tetraspanin hCD81 contains a large extracellular loop (LEL), which interacts with the E2 glycoprotein of HCV. The role of the non-LEL regions of hCD81 (intracellular tails, four transmembrane domains, small extracellular loop and intracellular loop) is poorly understood. Here, we studied the contribution of these domains to HCV susceptibility of hepatoma cells by generating chimeras of related tetraspanins with the hCD81 LEL. Our results show that non-LEL regions in addition to the LEL determine susceptibility of cells to HCV. While closely related tetraspanins ( CD81 and CD81) functionally complement hCD81 non-LEL regions, distantly related tetraspanins ( TSP9 amd TSP96F) do not and tetraspanins with intermediate homology (hCD9) show an intermediate phenotype. Tetraspanin homology and susceptibility to HCV correlate positively. For some chimeras, infectivity correlates with surface expression. In contrast, the hCD9 chimera is fully surface expressed, binds HCV E2 glycoprotein but is impaired in HCV receptor function. We demonstrate that a cholesterol-coordinating glutamate residue in CD81, which hCD9 lacks, promotes HCV infection. This work highlights the hCD81 non-LEL regions as additional HCV susceptibility-determining factors.