METHOD OF PREPARING ATTENUATED IMMUNOGENIC STRAINS OF PASTEURELLA MULTOCIDA Russian patent published in 1998 - IPC

FIELD: biotechnology, veterinary science, veterinary microbiology. SUBSTANCE: method involves two-stage selection of spontaneous and 2-aminopurine-induced mutants of pathogen Pasteurella multocida showing resistance to streptomycin. The obtained attenuated strains show the presence of two independent mutations. The first mutation makes cell resistance to 1000 mcg/mk streptomycin and second one provides increase of resistance level to this antibiotic up to 10000 mcg/ml and results to partial streptomycin-dependence. Each mutation ensures significant decrease of pathogen strain virulence and the presence of two independent mutations provides an assurance from reversion to the parent virulent state. EFFECT: improved and safety method of attenuation.