The egg lines of the Seerey Type A prime and the SSM Type B strains of influenza virus are sensitive to the hemagglutinin (HA)-inhibiting and the in ovo neutralizing activity of the β inhibitor in normal ox serum. Adaptation of the Seerey and SSM strains to CF1, CFW, and NIH mice is accompanied by the development of resistance to the HA-inhibiting and neutralizing effect of β inhibitor. The sudden and concomitant nature of the appearance of extensive pulmonary consolidation in 4 days and the development of resistance to HA-inhibition and neutralization by β inhibitor suggests that these changes are interrelated. Virus resistant to β inhibitor has also been isolated by passage of sensitive virus in eggs in the presence of ox serum.
These studies were aided by a contract between the Office of Naval Research, Department of the Navy and Hahnemann Medical College (NR 134–129) and in part by a grant from the Sidney Hillman Medical Center Research Fund.