Multiple Levels of Posttranscriptional Regulation of Influenza Virus Gene Expression

The genome of Influenza viruses consists of a set of single-stranded, negative-polarity ribonucleoproteins. Each one is replicated and transcribed as an independent unit in the nucleus of the infected cell. This property allows the existence of both nuclear and cytoplasmic regulatory steps in the control of viral gene expression at the posttranscriptional level. The regulation of mRNA splicing and nucleocytoplasmic mRNA transport and the preferential translation of viral mRNAs in the infected cell are discussed, stressing the possible role of NS1 protein in these processes.