The effect of interferon on the transcription pattern of parainfluenza virus 5

Abstract

Interferon (IFN) is activated in response to virus infections and upregulates interferon-stimulated genes (ISGs) resulting in the expression of hundreds of proteins, many of which have direct or indirect antiviral activity. Parainfluenza virus 5 (PIV5) of the Paramyxoviridae family is a non-segmented negative sense single-stranded RNA virus with seven genes encoding eight proteins. Here we present that IFN induces alterations in the pattern of both virus transcription and translation and that ISG56 is primarily responsible for these effects. We report that when cells were treated with IFN post-infection, virus protein synthesis was inhibited while virus transcription levels were increased. These results suggest that ISG56 selectively inhibits the translation of viral mRNAs. In addition, the relationship of various PIV5 isolates was analysed by next generation sequencing. Four areas with a high degree of single nucleotide polymorphisms (SNPs) were identified and mapped to the intergenic regions of NP-V/P, M-F and HN-L, as well as the entire SH gene. Three of the isolates, the porcine strain SER and the canine strains CPI+ and CPI-, did not express an SH protein due to the lack of a start codon. A low degree of variation was found in the amino acid sequence of the HN glycoprotein suggesting that PIV5 may be less pressured to evolve in order to evade immune responses, such as neutralising antibodies.