Live streptomycin-dependent Pasteurella multocida vaccine for the prevention of hemorrhagic septicemia.

A type B Pasteurella multocida was used for the development of a streptomycin-dependent (StrD) vaccine. Pasteurella multocida R-473, a hemorrhagic septicemia strain, was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine to increase the likelihood of encountering a StrD mutant and was plated on agar containing 400 microgram of streptomycin/ml. Replica plating was used to differentiate dependent from resistant colonies. Mice and rabbits were vaccinated with a StrD mutant and 21 days later, were challenge exposed, along with unvaccinated controls, with the wild type R-473. Protection of greater than 4 logs was shown for the vaccinated mice. All vaccinated rabbits were protected and all nonvaccinated controls succumbed to a challenge exposure of 500 or 1,000 LD50.