CD4 and infection: Finally, the time course of protective effects of M. vaccae NCTC 11659, in the context of spontaneous colitis and anxiety-like defensive behavioral responses (Reber et al., 2016b), are consistent with the time course of induction of Treg following infection of mice with a live strain of M. vaccae isolated from bovine submaxillary lymph nodes, in which CD4+CD25+Foxp3+ Treg are elevated within 1 week of infection, reach maximal levels 3 or 4 weeks following infection, and remain elevated until at least 8 weeks following infection (Zhang et al., 2016).