Identification of NS1-Hsp90 interaction in yeast by the CytoTrap two-hybrid system. Various bait (pSos) and prey (pMyr) plasmids were used for co-transformation of cdc25H yeast cells, representing a positive control (lane 1) and negative controls (lanes 2-7). Five independent cdc25H transformants were spotted on glucose (GLU) medium at 22°C (left panel) or 37°C (middle panel) and on galactose (GAL) medium at 37°C (right panel). Yeast transformants expressing NS1 (H5N1 and H3N2) and Hsp90 grew efficiently on galactose medium at 37°C (right panel, lane 8). 5NS1 represents H5N1 NS1 and 3NS1 represents H3N2 NS1.