Characterization of determinants important for hepatitis C virus p7 function in morphogenesis by using trans-complementation

Brohm, C., Steinmann, E., Friesland, M., Lorenz, I. C., Patel, A. , Penin, F., Bartenschlager, R. and Pietschmann, T. (2009) Characterization of determinants important for hepatitis C virus p7 function in morphogenesis by using trans-complementation. Journal of Virology, 83(22), pp. 11682-11693. (doi: 10.1128/JVI.00691-09) (PMID:19726506) (PMCID:PMC2772676)

Abstract

Hepatitis C virus (HCV) p7 is an integral membrane protein which forms ion channels in vitro and that is crucial for efficient assembly and release of infectious virions. Due to these properties, p7 was included into the family of viroporins that comprises proteins like influenza A virus M2 and HIV-1 vpu which alter membrane permeability and facilitate release of infectious viruses. P7 from different HCV isolates sustains virus production with variable efficiency. Moreover, p7 determinants modulate processing at the E2/p7 and the p7/NS2 signal peptidase cleavage sites and E2/p7 cleavage is incomplete. Consequently, it was unclear if differential ability to sustain virus production was due to variable ion channel activity or due to alternate processing at these sites. Therefore, we developed a trans-complementation assay permitting analysis of p7 outside of the HCV polyprotein and thus independent of processing. Rescue of p7-defective HCV genomes was accomplished by providing E2, p7 and NS2, or in some cases by p7 alone both in a transient complementation assay as well as in stable cell lines. In contrast, neither influenza A virus M2 nor HIV-1 vpu compensated defective p7 in HCV morphogenesis. Thus, p7 is absolutely essential for production of infectious HCV particles. Moreover, our data indicate that p7 can operate independent of an upstream signal sequence and that a tyrosine residue close to the conserved di-basic motif of p7 is important for optimal virus production in the context of genotype 2a viruses. The experimental system described here should be helpful to investigate further key determinants of p7 that are essential for its structure and function in the absence of secondary effects caused by altered polyprotein processing

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Patel, Professor Arvind
• Authors: Brohm, C., Steinmann, E., Friesland, M., Lorenz, I. C., Patel, A., Penin, F., Bartenschlager, R., and Pietschmann, T.
• College/School: College of Medical Veterinary and Life Sciences; College of Medical Veterinary and Life Sciences > School of Infection & Immunity > Centre for Virus Research
• Research Group: MRC Virology
• Journal Name: Journal of Virology
• Journal Abbr.: J. Virol.
• Publisher: American Society for Microbiology
• ISSN: 0022-538X
• ISSN (Online): 1070-6321
• Published Online: 02 September 2009