City Research Online

Abstract

Parainfluenza virus 5 (PIV5) is a negative sense RNA virus of the Paramyxoviridae family which causes both acute and persistent infections in cell culture and in vivo. Previous work had implicated alterations in the P protein which affect viral polymerase activity, as well as sensitivity to the interferon (IFN) system, as mechanisms by which persistent infection may be established. In the current study, the impact of alterations in the P protein on viral RNA synthesis were investigated by using a viral minigenome reporter assay, and changes around sites of phosphorylation in the P protein were found to have a dramatic effect on the rate of viral transcription, which we propose as a potential ‘switch’ mechanism between acute and persistent infections. Our previous work had identified IFIT1, which inhibits the translation of viral mRNA, as the IFN-stimulated gene primarily responsible for the sensitivity of PIV5 to IFN. Here, using minigenome reporter assays, PIV5 was shown to be sensitive to multiple IFIT proteins, in contrast to Measles virus which was insensitive. The sensitivity of PIV5 to IFIT1 was found to be due its failure to generate a fully-methylated mRNA cap structure, as determined by mass spectrometry analysis. In the course of our previous work on IFIT1, we showed that the effect of IFIT1 on translation was not equal between PIV5 genes. By demonstrating that cap-proximal RNA secondary structure affects the affinity of IFIT1 for viral mRNA, the differential sensitivity of PIV5 genes to IFIT1 was here shown to be a function of the presence or absence of RNA hairpin structures in the 5’ untranslated regions (5’UTRs) of PIV5 transcripts. The introduction of RNA secondary structure into an otherwise unstructured PIV5 5’UTR can confer protection from IFIT1 and reduce the inhibition of PIV5 growth by IFN. The implications of Pmutations and gene-specific sensitivity to IFIT1 are discussed in terms of persistent infection.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QR Microbiology > QR180 Immunology Q Science > QR Microbiology > QR355 Virology R Medicine
Departments:	School of Health & Medical Sciences > Infection and Immunity Research Institute School of Health & Medical Sciences > School of Health & Medical Sciences Doctoral Theses Doctoral Theses

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