HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Free via Open Access: OA OA Free Full Text Full Text (PDF) OA All Versions of this Article: vir.0.007336-0v1 90/6/1382    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Barry, G. Articles by Fazakerley, J. K. PubMed PubMed Citation Articles by Barry, G. Articles by Fazakerley, J. K. Agricola Articles by Barry, G. Articles by Fazakerley, J. K.

PKR acts early in infection to suppress Semliki Forest virus production and strongly enhances the type I interferon response

The Roslin Institute and Royal School of Veterinary Studies, College of Medicine and Veterinary Medicine, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK

Correspondence
John K. Fazakerley
John.Fazakerley{at}ed.ac.uk

The double-stranded RNA-activated protein kinase (PKR) is a key regulator of protein translation, interferon (IFN) expression and cell survival. Upon infection of vertebrate cells in continuous culture, the alphavirus Semliki Forest virus (SFV) initiates apoptosis and IFN synthesis. To determine the effect of PKR on SFV infection, we studied the course of infection in wild-type (wt) mice, mice with a genetic deletion of PKR (PKR^–/–) and mouse embryo fibroblasts (MEFs) derived from these mice. In MEFs, PKR delayed virus protein synthesis, production of infectious virus and caspase-3-activated cell death and reduced the yield of infectious virus by 90 %. Small interfering RNA suppression of PKR levels in NIH-3T3 cells also reduced virus production and apoptosis. In MEFs, PKR was not required for initiation of IFN-β gene transcription, but contributed strongly to the magnitude of this response. Levels of IFN-β transcripts in PKR^–/– MEFs at 8 h were 80 % lower than those in wt MEFs and levels of functional IFN at 24 h were 95 % lower. Following infection of wt and PKR^–/– mice, SFV4 and SFV A7(74) were avirulent. PKR increased levels of serum IFN and the rate of clearance of infectious virus from the brain. In summary, in response to SFV, PKR exerts an early antiviral effect that delays virus protein production and release of infectious virus and, whilst PKR is not required for induction of apoptosis or activation of the type I IFN response, it strongly augments the type I IFN response and contributes to clearance of infectious virus from the mouse brain.