• Vaccine Name: B. suis strain VTRS1
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0000303
• Type: Attenuated live vaccine
• Preparation: The rough mutant VTRS1 was obtained from B. suis 2579 by allelic exchange of the rfbU gene encoding mannosyltransferase with a Tn5-disrupted rfbU gene (Winter et al., 1996).
• Virulence: VTRS1, like RB51, is a stable rough form of the bacterium. It does not manifest evidence of reversion during passage in mice (Winter et al., 1996).
• Description: Vaccination with the rough strain VTRS1 induces protection against virulent strains of B. abortus (2308), B melitensis (16M), B. suis biovar 1 (750), B. suis biovar 4 (2579) (Winter et al., 1996).

Mouse Response

• Vaccination Protocol: Mice, (eight to nine weeks old), in experimental groups of five, were vaccinated with live vaccines: VTRM1, VTRS1, and Rev 1 with 5 x 10^4 CFU (IV); strain 19 (S19) 5 x 10^3 CFU given IV; and RB51, 3 x 10^8 CFU given i.p. All vaccines except RB51 were obtained from frozen stock cultures. The large dose of RB51 administered required that stock cultures be cultured on plates, and after three days diluted to the appropriate concentration (Winter et al., 1996).
• Challenge Protocol: Eight weeks after the initial vaccination, mice were challenged IV with 5x10^4 CFU of Brucella. From challenge exposure to euthanasia was 2 weeks for all Brucella strains except B abortus 8-954 and 2-1230. For these strains a 1-week interval was used. Mice were euthanized with CO2. Individual spleens were homogenized, diluted serially, and plated on Schaedler blood agar. Colonies were counted after incubation for 3 days (B. abortus, B. melitensis, and B. suis) or 4 to 5 days (B. ovis) at 37 C under 10% CO2 (Winter et al., 1996).
• Efficacy: VTRM1 and VTRS1 were effective in inducing protection against virulent strains of heterologous, as well as the homologous, Brucella spp. Vaccination with either strain conferred protection against challenge exposure with virulent laboratory strains of B. abortus, B. melitensis, and B. suis of biovars 1 and 4. VTRM1 also provided protection against B. ovis (Winter et al., 1996).