FIG 4.

The pneumococcal dlt locus is epistatic to the host pattern recognition receptor TLR2. (A) Congenic tlr2^−/− pups were colonized at age 4 days with the WT strain (T4S) or with its isogenic dlt-negative construct. Daily shedding in nasal secretions was quantified from ages 5 to 9 days, with the median values being indicated and with each symbol representing the number of CFU observed from a single pup on a single day. Data are for 8 pups per group. (B) Colonization density in URT lavage fluids obtained at age 9 days, with the median value being shown. (C) Number of neutrophils determined by flow cytometry (CD45⁺, CD11b⁺, and Ly6G⁺ events) in URT lavage fluids obtained from tlr2^−/− pups inoculated with either the WT strain (T4S) or its isogenic dlt-negative construct at age 7 days. Values are ±SEM (n = 8 to 11 pups/group). (D) Gene expression in colonized tlr2^−/− pups infected with the dlt-negative construct relative to those infected with the WT (T4S) at age 7 days, as measured by qRT-PCR for the chemokine/cytokine shown. Values are ±SEM (n > 8). n.s, not significant.