An overlapping protein-coding region in Influenza A Virus Segment 3 modulates the host response. Mus musculus

Segment 3 of influenza A virus contains a second open reading frame accessed via robosomal frameshifting. The frameshift product, PA-Z, comprises the endonuclease domain of viral PA protein with C-terminal demain encoded by the X-ORF and functions to repress cellular gene expression. PA-X also modulates IAV virulence in a mouse infection model. Overall design: The effect of PA-X deltions were examined using 2 separate mutant influenza viruses (1918-FS/1918-PCT1) and the results compared to wild-type 1918 influenza virus. Balb/c mice were infected and samples harvested at days 3, 5 and 8 days. Four animals/condition were used. Gene expression levels from infected animals were compared to mock animals.