Splicing of influenza A virus NS1 mRNA is independent of the viral NS1 protein.
RNA segment 8 (NS) of influenza A virus encodes two proteins. The NS1 protein is translated from the unspliced primary mRNA transcript, whereas the second protein encoded by this segment, NS2/NEP, is translated from a spliced mRNA. Splicing of influenza NS1 mRNA is thought to be regulated so that the levels of NS2 spliced transcripts are approximately 10 % of total NS mRNA. Regulation of splicing of the NS1 mRNA has been studied at length, and a number of often-contradictory control mechanisms have been proposed. In this study, we used (32)P-labelled gene-specific primers to investigate influenza A NS1 mRNA splicing regulation. It was found that the efficiency of splicing of NS1 mRNA was maintained at similar levels in both virus infection and ribonucleoprotein-reconstitution assays, and NS2 mRNA comprised approximately 15 % of total NS mRNA in both assays. The effect of NS1 protein expression on the accumulation of viral NS2 mRNA and spliced cellular beta-globin mRNA was analysed, and it was found that NS1 protein expression reduced spliced beta-globin mRNA levels, but had no effect on the accumulation of NS2 mRNA. We conclude that the NS1 protein specifically inhibits the accumulation of cellular RNA polymerase II-driven mRNAs, but does not affect the splicing of its own viral NS1 mRNA.
Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
Nicole C
NC
Robb
David
D
Jackson
Frank T
FT
Vreede
Ervin
E
Fodor
D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D005814:Genes, Viral; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000502:physiology; D006801:Humans; D009980:Influenza A virus / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism; D055544:beta-Globins / Q000235:genetics
D017931:DNA Primers; C085820:INS1 protein, influenza virus; D012333:RNA, Messenger; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; D055544:beta-Globins