Growth kinetics in HAE of PR8+Vic HA/NA and PR8+Chick HA/NA inoculated at equal MOI (0.01) revealed that PR8+Vic HA/NA infection and growth was efficient at both 32uC and 37uC ( Figure 6A ). PR8+Chick HA/NA grew at 37uC to identical titers as PR8+Vic HA/NA at 32uC recapitulating our data obtained for wholly human (A/Victoria/3/75) and wholly avian (A/Dk/Eng/ 62) viruses. In contrast, PR8+Chick HA/NA was severely delayed in growth at 32uC and generated titers that were .2 logs less than titers obtained for this virus at 37uC at both 24 and 48 hrs pi. Indeed, PR8+Chick HA/NA, like A/Dk/Eng/62 avian influenza virus ( Figure 1A) , was significantly restricted for growth at 32uC at 12, 24 and 48 hrs pi compared to growth at 37uC and growth of PR8+Vic HA/NA at either temperature.