The accumulation of influenza A virus segment 7 spliced mRNAs is regulated by the NS1 protein
Journal of General Virology 93:1 (2012) 113-118
Abstract:
The influenza A virus M1 mRNA is alternatively spliced to produce M2 mRNA, mRNA 3, and in some cases, M4 mRNA. Splicing of influenza mRNAs is carried out by the cellular splicing machinery and is thought to be regulated, as both spliced and unspliced mRNAs encode proteins. In this study, we used radioactively labelled primers to investigate the accumulation of spliced and unspliced M segment mRNAs in viral infection and ribonucleoprotein (RNP) reconstitution assays in which only the minimal components required for transcription and replication to occur were expressed. We found that co-expression of the viral NS1 protein in an RNP reconstitution assay altered the accumulation of spliced mRNAs compared with when it was absent, and that this activity was dependent on the RNA-binding ability of NS1. These findings suggest that the NS1 protein plays a role in the regulation of splicing of influenza virus M1 mRNA. © 2012 SGM.The accumulation of influenza A virus segment 7 spliced mRNAs is regulated by the NS1 protein.
The Journal of general virology 93:Pt 1 (2012) 113-118
Abstract:
The influenza A virus M1 mRNA is alternatively spliced to produce M2 mRNA, mRNA(3), and in some cases, M4 mRNA. Splicing of influenza mRNAs is carried out by the cellular splicing machinery and is thought to be regulated, as both spliced and unspliced mRNAs encode proteins. In this study, we used radioactively labelled primers to investigate the accumulation of spliced and unspliced M segment mRNAs in viral infection and ribonucleoprotein (RNP) reconstitution assays in which only the minimal components required for transcription and replication to occur were expressed. We found that co-expression of the viral NS1 protein in an RNP reconstitution assay altered the accumulation of spliced mRNAs compared with when it was absent, and that this activity was dependent on the RNA-binding ability of NS1. These findings suggest that the NS1 protein plays a role in the regulation of splicing of influenza virus M1 mRNA.Identification of a novel splice variant form of the influenza A virus M2 ion channel with an antigenically distinct ectodomain.
PLoS Pathog 8:11 (2012) e1002998
Abstract:
Segment 7 of influenza A virus produces up to four mRNAs. Unspliced transcripts encode M1, spliced mRNA2 encodes the M2 ion channel, while protein products from spliced mRNAs 3 and 4 have not previously been identified. The M2 protein plays important roles in virus entry and assembly, and is a target for antiviral drugs and vaccination. Surprisingly, M2 is not essential for virus replication in a laboratory setting, although its loss attenuates the virus. To better understand how IAV might replicate without M2, we studied the reversion mechanism of an M2-null virus. Serial passage of a virus lacking the mRNA2 splice donor site identified a single nucleotide pseudoreverting mutation, which restored growth in cell culture and virulence in mice by upregulating mRNA4 synthesis rather than by reinstating mRNA2 production. We show that mRNA4 encodes a novel M2-related protein (designated M42) with an antigenically distinct ectodomain that can functionally replace M2 despite showing clear differences in intracellular localisation, being largely retained in the Golgi compartment. We also show that the expression of two distinct ion channel proteins is not unique to laboratory-adapted viruses but, most notably, was also a feature of the 1983 North American outbreak of H5N2 highly pathogenic avian influenza virus. In identifying a 14th influenza A polypeptide, our data reinforce the unexpectedly high coding capacity of the viral genome and have implications for virus evolution, as well as for understanding the role of M2 in the virus life cycle.Single-Molecule Studies of Transcription Initiation using a Vesicle Approach
BIOPHYSICAL JOURNAL 102:3 (2012) 485A-485A
The influenza A virus NS1 protein interacts with the nucleoprotein of viral ribonucleoprotein complexes.
Journal of virology 85:10 (2011) 5228-5231