Genetic stability of Brucella abortus S19 and RB51 vaccine strains by multiple locus variable number tandem repeat analysis (MLVA16).

The aims of the present study were (i) to assess the in vitro genetic stability of S19 and RB51 Brucella abortus vaccines strains and (ii) to evaluate the ability of multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) as a tool to be used in the quality control of live vaccines against brucellosis. Sixty-three batches of commercial S19 (n=53) and RB51 (n=10) vaccines, produced between 2006 and 2009, were used in this study. S19 and RB51 vaccines were obtained from, respectively, seven and two different manufacturers.