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Am J Vet Res. 1998 Aug;59(8):1016-20.

Field study of vaccination of cattle with Brucella abortus strains RB51 and 19 under high and low disease prevalence.

Author information

1
Laboratorio de Brucelosis, indtituto de investigaciones Veterinarias, Maracay, Venezuela.

Abstract

OBJECTIVE:

To assess humoral and protective immunity in cattle vaccinated by 12 months with Brucella abortus vaccine strains RB51 and 19 under field conditions of high and low brucellosis prevalence.

ANIMALS:

450 seronegative female cattle: 330 three to eight months old (calves), and 120 ten to twelve months old (heifers).

PROCEDURES:

Ranch A had high prevalence (39%) of brucellosis, and ranch B had low prevalence (2%), as determined by results of conventional serologic testing: agar gel immunodiffusion and the ring test. Seronegative cattle were vaccinated once or twice with 5 x 10(9) colony-forming units of B abortus strain RB51 or once with strain 19. After vaccinating 285 cattle with strain RB51 and 165 with strain 19, 74 (26%) and 30 (18%), respectively, were bred to seropositive bulls, then were kept within the infected herd of origin.

RESULTS:

All cattle vaccinated with strain 19 seroconverted 30 days later. All 285 cattle vaccinated with strain RB51 had negative results for all serologic tests, including agar gel immunodiffusion. All RB51-vaccinated cattle that became pregnant had negative results for the ring test and for conventional serologic tests after their first calving.

CONCLUSIONS:

Strain RB51 can be used as a live organism vaccine without inducing antibody titers that interfere with serodiagnosis, and induced 100% protection against field strain B abortus-induced abortion in cattle vaccinated at least 1 year before mating to an infected bull. Vaccination with strain 19 under similar conditions was less effective than vaccination with strain RB51.

PMID:
9706206
[Indexed for MEDLINE]

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