The Egg-White Inhibitor of Influenza Virus Hemagglutination

Abstract

Summary Ten per cent solutions of egg-white, preserved with 0.25 per cent phenol, 0.02 per cent Merthiolate (Lilly), or 0.05 per cent formalin and stored at 4 C, were titrated periodically for inhibitory activity against hemagglutination by heated, purified swine influenza virus. No significant change in activity could be demonstrated over a period which exceeded 7 months for some of the preparations. Phenol proved more effective than Merthiolate or formalin in prohibiting the growth of micro-organisms and is, accordingly, preferred for preservation of standard solutions. Frozen samples of unpreserved egg-white and samples dried from the frozen state in vacuo gave irregular results. The high stability of the inhibitory activity of preserved solutions was confirmed by the experimental identity of the slopes of inhibition curves for aged and fresh samples of egg-white. The usefulness of slope as a criterion of degradation of the inhibitor is illustrated by results obtained when inhibitor is heated at 100 C or treated with crystalline chymotrypsin. With the aid of a standard solution it was found that the inhibitory activity is highly stable in semipurified preparations of inhibitor. Data are presented to illustrate the accuracy of the inhibition titrations, the variation of activity among individual egg-whites, and the essential absence of dependence of the inhibition titer on the individual source of the chicken red cells used in the tests.