[The immunological activity of the bacterial strain Escherichia coli M17 used in preparing a commercial preparation of colibacterin].

The toxicity, immunogenic properties and protective activity of the live culture of E. coli M17 and antigenic preparations obtained from cell suspensions of this strain have been studied under experimental conditions. As revealed in experiments on mice, E. coli M17 live culture has low virulence, moderate toxicity and provides the protection of immunized mice from challenge with homologous and highly virulent E. coli strains. E. coli M17 live culture, when introduced orally or intravenously into rabbits, ensures the synthesis of 02 and H6 antibodies. Blood sera taken from immunized rabbits yield better results than initial sera in experiments on the passive protection of mice. The results of our experiments show the expediency of the clinical trials of Colibacterin as a perspective Escherichia live oral vaccine.