Separation and concentration of a thermolabile precipitinogen from Shigella dysenteriae (Shiga)

Abstract

Presence of thermolabile agglutination-inhibiting substances in strains of the genus Shigella has been demonstrated by numerous authors. Archer (1942) used as antigen for agglutination tests with S. alkalescens cultures which had been killed at 100° C., since a thermolabile factor which prevents agglutination by the usual technique had been found present in the organism. The same method was employed by Mendes Silva (1943) in agglutination tests with S. ambigua. Braun & Unat (1943) found in S. paradysenteriae (Flexner) a labile antigen designated ‘O1’ which inhibits O-agglutination of the living bacteria. Schuetze (1944) reported that the insensitivity of S. dysenteriae (Shiga) to agglutination is abolished by heating at 100° C. for 30 min. Weil, Black & Farsetta (1944) reported that boiling for 1 hr. renders inagglutinable strains of S. paradysenteriae (Flexner) fully agglutinable. Recently, Weil et al. (1946) reported that one of the Sachs types contains an inhibiting substance, a heat labile antigen and a heat stable antigen. He observed inhibition of agglutination of living bacteria in many Flexner types, S. alkalescens and S. ambigua. Olitzki, Shelubsky & Koch (1946) reported that there is present in S. dysenteriae (Shiga) a labile substance ‘I’ which inhibits the agglutination of thd living bacteria. They were able to demonstrate a labile antigen in toxic saline extracts but not in the intact bacteria. The present paper reports a method for isolation of this antigen in the form of a relatively concentrated preparation.