In vitro markers and biological activity in mice of seed lot strains and commercial Brucella melitensis Rev 1 and Brucella abortus B19 vaccines

Four seed lots and fourteen batches of Brucella melitensis Rev 1 and B, abo rtus B19 living anti-Brucella commercial vaccines obtained from six Spanish laboratories were tested in vitro and in vivo in the reference mouse model for quality control. All the strains tested showed the characteristic morp hology of their respective Rev 1 or B19 reference strains with the exceptio n of three Rev 1 strains: seed lot SL2 and commercial vaccine R3, in which giant colonies were predominant, and commercial vaccine R5, in which 5% rou gh colonies were detected. Strains SL2 and R5 (but not the R3) had a defici ent activity when tested in the mouse model. All strains but two (Rev 1 str ain R1 and B19 strain B2) had standard resistance/ sensitivity patterns to streptomycin and penicillin G. Strains R1 and B2 had an increased resistanc e to penicillin when incubated in a 10% CO2 atmosphere and both strains sho wed an increased residual virulence in mice. As residual virulence and immu nogenicity in mice were not always correlated one another nor with the in v itro tests, all tests should be performed to control properly the anti-Bruc ella live vaccines. A computerized statistical procedure to calculate the r esidual virulence of vaccines is proposed as an alternative to that used in the current method. (C) 2000 The International Association for Biologicals .