FIG. 2.

Chlamydial burden in the lungs of neonatal IFN-γ^−/−, IFN-γR^−/−, and IL-12p35^−/− mice following i.n. C. muridarum challenge. Groups (n = 4) of 1-day-old IFN-γ^−/− or IFN-γR^−/− or IL-12p35^−/− mice were challenged i.n. with 100 IFU of C. muridarum or treated with PBS (mock). The tissues were harvested at the indicated days after challenge and chlamydial burden was quantitated. (A) BALB/c IFN-γ^+/+ and IFN-γ^−/− mice. *P ≤ 0.05 (Student's t-test). (B) C57BL/6, IFN-γR^−/−, and IL-12p35^−/− animals. *P ≤ 0.05 between C. muridarum-challenged C57BL/6 and IFN-γR^−/− or C57BL/6 and IL-12p35^−/− mice (Student's t-test). The results are expressed as the mean ± SD of chlamydial IFU per group and are representative of 2 independent experiments.