Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 5, 1996
Publication Date: N/A
Interpretive Summary: A new Brucella abortus vaccine, strain RB51, (SRB51) offers a diagnostic advantage over the currently used B. abortus strain 19. It does not induce positive serologic titers in previously unvaccinated animals but does protect against challenge with virulent B. abortus strains. However, there has been concern that the low amount of LPS O-side chain expressed by SRB51 might cause seropositive responses when administered to adult animals previously vaccinated with S19 during calfhood. This study demonstrated that adult animals (2-10 years of age) vaccinated during calfhood do not develop positive serologic titers on conventional brucellosis diagnostic tests following vaccination with SRB51. Therefore, administration of SRB51 to adult animals will not confound identification of infected herds.
This study was designed to determine if Brucella abortus strain RB51 (SRB51), which expresses small amounts of the lipopolysaccharide O- side chain, would cause anamnestic responses on serological surveillance tests when given to adult cattle that were calfhood vaccinated with B. abortus strain 19 (S19). Cattle vaccinated as adults with SRB51 that had been vaccinated in calfhood with S19 (n=40) had significantly greater (P<0.05) antibody titers against SRB51 at 4 and 8 weeks post-vaccination in the dot blot assay when compared to animals (n=10) not vaccinated with SRB51. At 4 and 8 wk following SRB51 vaccination, sera from all SRB51-vaccinates were negative on the card, buffered acid plate agglutination (BAPA), complement fixation (CF), standard tube agglutination (STA), and particle concentration fluorescence immunoassay (PCFIA) tests with the exception of 10 samples. This study indicates SRB51-vaccination of adult animals that were calfhood vaccinated with S19 may cause a small percentage of transient positive responses on brucellosis tests with high sensitivity, but will not cause detectable antibody titers when evaluated by other highly specific conventional serological tests.