Quantitative Methods in the Study of the Phage-Antiphage Reaction

Abstract

The following characteristics of antiphage-sera have been defined, and methods given for their measurement: specifically precipitable nitrogen, specific rate of neutralization, neutralizing capacity, precipitating activity, and combining power. The significance and precision of measurement of these characteristics are briefly discussed. The methods have been designed specifically to study equilibria in immune reactions, and the question of the homogeneity of the reactants. The specifically precipitable nitrogen of a coli-phage in crude lysates was found to correspond to less than 10⁻¹³ mg per lytic unit. This determination provides an additional method for estimating the size of the infective dose of viruses, which can be obtained in sufficient concentration.