Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 10, 1998
Publication Date: N/A
Technical Abstract: Brucella abortus strain RB51 is a new brucellosis vaccine for cattle that offers advantages over previously used vaccines. Strain RB51 has very low expression, or does not express, the lipopolysaccharide O-side chain. Calfhood or adult vaccination with strain RB51 does not induce antibody responses that cause positive responses on conventional brucellosis surveillance tests. Therefore, strain RB51 vaccination does not interfere with detection of cattle infected with field strains of B. abortus. Strain RB51 localizes in lymphatic tissues and does not cause significant histological lesions in any tissue. When administered subcutaneously to calves between 4 and 10 months of age, dosages of 10*10 colony-forming units (CFU) are cleared by most cattle within 12 weeks. When compared to nonvaccinated cattle, calfhood vaccination with 10*10 CFU of strain RB51 induces significant protection against abortion or infection following midgestational challenge with 10*7 CFU of virulent B. abortus strain 2308 Data from our studies suggest that calfhood vaccination with strain RB51 or B. abortus strain 19 induce similar levels of protection against abortion or infection.