TABLE 4.

Secretory IgG2a in the genital tract after i.v. challenge of preexposed BALB/c mice with MoPn

Day postchallenge	Mean IgG2a antibody concn (ng/ml) ± SEMa
	p.o.	i.v.	i.n.	s.c.
7	6.85 ± 1.8	5.96 ± 0.4	26.00 ± 1.9	3.46 ± 0.7
14	6.24 ± 0.6	6.80 ± 0.34	35.53 ± 5.6	3.96 ± 0.61
21	3.71 ± 0.1	7.53 ± 1.2	55.28 ± 11.4	17.53 ± 2.8

^aFemale BALB/c mice were infected with MoPn by the indicated route and then challenged i.v. 70 days later. Vaginal washes were performed at different times after challenge of preinfected mice with 250 μl of PBS as previously described (32) and stored at −70°C until assayed. The levels of chlamydia-specific secretory IgG2a antibodies in vaginal washes were measured by a modified standard ELISA procedure as previously described (26, 27). Results represent the mean of triplicate wells for each set of samples obtained from different experiments. Experiments were repeated two times to obtain data for 10 or 12 animals per group.