[Production of live attenuated vaccine against colibacillosis in pigs]

Two strains of beta-hemolytic Escherichia coli, p-0141 and i-0149 were used to obtain mutant E. coli organisms with unchanged cultural, morphological, biochemical, and serological properties. The mutants proved apathogenic for albino mice at intravenous injection of a 6-hour broth culture at the rate of 0.3 cm3 or an endotoxin in the same dose. Neither were they enteropathogenic for pigs when inoculated into intestinal segments. They could be used as vaccinal strains.