DAP and infection: Kikuchi et al. [38] demonstrated that the enzyme called D-alanyl-D-alanine carboxypeptidase (DAP) contributes to the NO resistance and is required for the intracellular growth of B. abortus. Conversely, higher levels of ROS were observed at the early stages of infection when the CFU numbers of WT or mutants are recovered in a smaller numbers, suggesting that B. ovis may be susceptible to bactericidal effect of ROS, as previously demonstrated for B. abortus [34,35].