Effect of Trypsin on a Susceptible Strain of Influenza A Virus

[摘要] The study dealt with a trypsin-sensitive line of influenza A virus. Incubation of this virus with 0.25% crude (Difco 1:250) or crystalline trypsin for 1 hr at 37°C completely destroyed the hemagglutinins and reduced the egg infectivity by more than 99%. A second line of virus derived from the same isolate as the trypsin-sensitive line and closely related to it antigenically, and several other strains of influenza A, showed no significant decrease in either hemagglutinins or infectivity when treated in a similar manner.Crude trypsin inactivated the sensitive virus at a more rapid rate than did crystalline trypsin. The results presented indicate that the crude product contains some heat labile constituent(s) which alone is incapable of inactivating the virus but which does make it more readily available to trypsin action.All preparations of the sensitive virus appeared to contain a small percentage of trypsinresistant particles, but subcultures of these particles in embryonated eggs always yielded virus populations composed primarily of trypsinsensitive virus, and in that respect they were indistinguishable from the original virus suspension. By employing special procedures, a stable line of virus that possessed greatly increased resistance to trypsin was obtained from the sensitive strain.Repeated passage of the sensitive virus at either high or low dilution caused no significant variation in its susceptibility to trypsin, which suggests that this property might serve as an easily recognized and stable marker for genetic studies.

[学科分类] 生物科学（综合）