Grant: Operating Grant

A hallmark of influenza virus is its genetic variability. Antigenic drift and shift lead to rapid (approx. yearly) generation of distinct virus clones that the human immune system normally does not recognize. All viruses depend upon host cells to replicate. Virus infection causes profound changes in infected cells and some of these have been determined by "gene arrays". However, the way(s) viruses alter host proteins (the effecter molecules in cells) remains poorly understood in most virus systems. We will use an integrated 2-pronged approach to determine how influenza virus infection alters host proteins and which "non-critical" host genes are absolutely required by the virus for its replication and pathogenesis. Preliminary studies have been completed in tissue-culture cells. Here, we will extend these analyses to more relevant primary cells. Cells will be infected with various H1N1 viruses, including non-pathogenic, mildly pathogenic seasonal flu strains, and pathogenic strains, including the current pandemic swine-origin H1N1 virus and the 1918 virus. Changes in 1000s of host protein levels will be measured by "SILAC" (Stable Isotope Labeling with Amino acids in Cell culture), and processed by multi-dimensional liquid chromatography/mass spectrometry. Critical, but "non-essential" host genes will be identified by genome-wide RNA interference screens and resultant cells that survive virus infection characterized and tested for their capacity to resist infection by other influenza viruses.