Temperature and Host Cell Factors in the Growth of Influenza Virus (PR8 Strain) in Avian Tissues in Vitro

This study demonstrates that with PR8 strain of influenza A virus in tissue cultures of avian embryonic lung, raising the temperature of incubation from 37 to 41°C does not prevent virus multiplication. In contrast to embryonic lung tissue, lung tissue from 2-day hatched chicks gives no clear-cut evidence of virus under any of the conditions studied. Using embryonic tissues, PR8 virus multiplication, as evidenced by a rise in egg infectivity titer, is greatest with lung and chorioallantoic membrane tissue, less marked with skin-muscle, gut and liver tissue, and not detectable in the case of heart tissue. The maturation of tissues from the embryonic stage to that of the 2-day hatched chick is associated with the loss of capacity to support PR8 virus multiplication. This difference in tissue susceptibility does not appear to be due to alteration of the environmental temperature of the cells from that of the embryo (37°C) to that of the hatched chick (41°C).