Immunity to leptospirosis: Leptospira interrogans serotype pomona bacterins in cattle.

Immunity to renal leptospirosis was demonstrated in cattle vaccinated with Leptospira interrogans serotype pomona. Vaccinated cattle, challenge inoculated with virulent L interrogans serotype pomona organisms 12 months after vaccination, were resistant to renal infection; similarly inoculated, but nonvaccinated, cattle were susceptible to renal infection. Relationship was demonstrated between immunity induced in vaccinated cattle and that induced in hamsters vaccinated with a dilution of the same bacterin and later inoculated with virulent L interrogans serotype pomona organisms.