FIG 5.

Bsr4 is dispensable for B. abortus infection of macrophages and experimentally infected mice. (A) Survival and replication of B. abortus strains in naive peritoneal macrophages. Peritoneal macrophages from BALB/c mice were infected with B. abortus 2308 or with B. abortus bsr4. At the indicated time points, the macrophages were lysed, and the number of intracellular brucellae present was enumerated following serial dilution and plating on agar medium. The data are presented as the average number of brucellae plus or minus the standard deviation of three replicate wells of macrophages infected with a specific Brucella strain. The results are from a representative experiment that was performed independently three times. (B) Spleen colonization of experimentally infected mice by B. abortus strains. BALB/c mice were infected intraperitoneally with B. abortus 2308 or with B. abortus bsr4. Mice were euthanized 4 and 8 weeks postinfection, and the number of brucellae colonizing the spleens of the mice was determined. The data are presented as the average number of brucellae plus or minus the standard deviation from 5 mice colonized with a specific Brucella strain at a particular time point. The data are from a single experiment using 5 mice per bacterial strain per time point (i.e., n = 5).