[Isolation and characterization of ts-mutants of Pasteurella multocida]

Temperature-sensitive mutants were isolated and characterised from wild strains of A, D, and A/D serotypes of Pasteurella multocida by mutagenic treatment, using N-methyl-N-nitro-n-nitrosoguanidine. The mutants differed from parent strains by growth intensity at 41 degrees C and 43 degrees C as well as by reduced virulence to mice and decreased toxin formation capacity. Mice were totally protected from intraperitoneal challenge infection, using the tenfold LD100, by two subcutaneous injections of 10(7) mutant germs.