A reduced frequency of lung CD11c+ cells expressing CCR7 was detected in B. pertussis-infected mice compared to cells derived from B. parapertussis and BpΔPTX infections, which were 0.53, 0.80, and 0.76- fold, respectively, over corresponding cells in uninfected mice (p<0.05) (Fig. 5E). This evidence concerns the gene CCR7 and infection.