Herpes simplex virus-1 induces expression of a novel MxA isoform that enhances viral replication.

ABSTRACT: MxA is an antiviral protein induced by interferon (IFN)-?/? that is known to inhibit the replication of many RNA viruses. In these experiments, the 76-kDa MxA protein expressed in IFN-?-treated cells was shown to have antiviral activity against herpes simplex virus-1 (HSV-1), a human DNA virus. However, MxA was expressed as a 56-kDa protein in HSV-1-infected cells in the absence of IFN-?. This previously unrecognized MxA isoform was produced from an alternatively spliced MxA transcript that had a deletion of Exons 14-16 and a frame shift altering the C-terminus. The variant MxA (varMxA) isoform was associated with HSV-1 regulatory proteins and virions in nuclear replication compartments. varMxA expression enhanced HSV-1 infection as shown by a reduction in infectious virus titers from cells in which MxA had been inhibited by RNA interference and by an increase in HSV-1 titers when the 56-kDa varMxA was expressed constitutively. Thus, the human MxA gene encodes two MxA isoforms, which are expressed differentially depending on whether the stimulus is IFN-? or HSV-1. These findings show that alternative splicing of cellular mRNA can result in expression of a novel isoform of a host defense gene that supports instead of restricting viral infection.

SUBMITTER: Ku CC 

PROVIDER: S-EPMC5520797 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature