• Vaccine Name: B. abortus strain 19
• Target Pathogen: Brucella spp.
• Target Disease: Brucellosis
• Vaccine Ontology ID: VO_0000022
• Type: Attenuated live vaccine
• Status: Licensed
• Location Licensed: USA; European countries
• Host Species for Licensed Use: Cattle
• Antigen: Whole Brucella organism
• Preparation: Strain 19, first described in 1930, is a laboratory-derived strain attenuated by an unknown process. It was originally isolated from bovine milk as a virulent strain in 1923, but became attenuated after storage at room temperature for over a year. Strain 19 is able to induce protective immunity in cattle (Schurig et al., 2002).
• Virulence: Although effective, strain 19 vaccine has a tropism for the placenta and causes abortion when given to pregnant cows , is infectious for humans , and causes serologic responses in calves that are the same as those in cattle infected with natural field strains (Cheville, 2000).
• Description: Strain 19 induces reasonable protection against B. abortus, but at the expense of persistent serological responses (Schurig et al., 2002).

Cattle Response

• Vaccination Protocol: Mature female cattle were immunized with strain 19 ( 2x10^8 and 6x10^8 CFU respectively) and 6-12 month old calves with strain 19 ( 4x10^10 and 12x10^10 CFU ) . Mature females and calves were inoculated with sterile vaccine diluent and formed a non-vaccinated, in-contact control group (Geong et al., 2000).
• Challenge Protocol: Cattle were allowed to graze for 24 months under conditions where infection was possible (Geong et al., 2000).
• Efficacy: Of the 599 animals bled initially, 83.5, 72.6, 73.8 and 64.1%, respectively, were represented at 3, 6, 9 and 24 months post infection, respectively. No significant differences between the two villages in the percentage of animals presented at each sampling were found. During the trials, no difference was observed in the presenting of animals identified as seropositive and those identified as seronegative (Geong et al., 2000).

Mouse Response

• Vaccination Protocol: Mice (10/treatment group) were injected i.p. with 0.2 ml of a 0.15 M NaCl saline solution (controls) or with 0.2 ml of saline containing approximately 1x10^5 cfu of strain 2308 or 1x10^7 cfu of strain 19 or RB51. Blood samples and spleens were taken from age-matched noninfected control mice and from infected mice at 2, 4, 6, 10, or 20 weeks respectively after infection (Stevens et al., 1994b).
• Challenge Protocol: No challenge performed.