[The protective activity of Yersinia pseudotuberculosis antigens].

Samples of Y.pseudotuberculosis (serovar I) antigens, represent a high-molecular lipopolysaccharide (LPS) fraction with a mol. wt. of 22.5 kD and fractions of outer membrane proteins isolated by the method of M. Osborn and R. Munson (1974), were tested in comparison with the activity with live cells of Y. pseudotuberculosis I attenuated mutant KV 9/2, having lost its Cad plasmid of virulence with a mol. wt. of 47 MD and carrying 2 attenuating markers: resistance to crystal violet and nalidixic acid. In experiments on guinea pigs pathomorphological studies demonstrated high protective activity of Y.pseudotuberculosis I attenuated mutant KV 9/2 and a pronounced protective effect achieved after the immunization of the animals with complex biopolymers, including a high-molecular LPS fraction and outer membrane proteins.