Direct characterization of influenza viral NS1 mRNA and related sequences from infected HeLa cells and a cell-free transcription system.

The NS1 mRNA of the influenza A virus WSN (H0N1) strain was isolated from a cell-free transcription system, and from the cytoplasm of virus-infected HeLa cells. The 32P-labeled NS1 mRNA derived from the infected cell cytoplasm was characterized by the secondary enzymatic analysis of sixteen of its large or distinct RNAase T1-resistant oligonucleotides. Several WSN strain-specific nucleotide differences from the previously-determined sequence of NS1 mRNA from the PR8 (H0N1) strain of influenza A virus, were located within these sequences. The RNAase T1-resistant oligonucleotides were placed within the primary sequence of NS1 mRNA, using the PR8 strain sequence data. The resulting linear map was then used to identify NS2 mRNA isolated from the infected cell cytoplasm, and an NS-related RNA species generated from NS1 mRNA incubated in a HeLa cell-free extract.