FIG. 1.

Identification of cellular proteins that enhance influenza virus replication. Cells were transfected with plasmids encoding the HK483 (H5N1) PB2, PB1, PA, and NP proteins (the PB2 protein possesses glutamic acid at position 627; PB2-627E). Cells were cotransfected with PolI-EGFP for the synthesis of a virus-like RNA and with an avian (quail cell) cDNA expression library. Cells expressing avian proteins that support efficient replication by PB2-627E in mammalian cells at 33°C produce increased amounts of EGFP. GFP-expressing cells were selected by a FACS cell sorter. After three rounds of selection, plasmid DNA was extracted from the cells and sequenced.