Genital-tract infection and disease in nude and immunologically competent mice after inoculation of a human strain of Chlamydia trachomatis.

A fast, human strain of Chlamydia trachomatis was introduced into the uterus of progesterone-treated CBA mice and congenic CBA nude mice through the uterine wall or via the cervical canal. The numbers of inclusions produced by samples taken from the vagina of the nude mice were significantly greater (P less than 0.05) than those produced by samples from immunologically competent normal mice. However, the infection was self-limited, lasting about 60 days, and there was no statistical difference in its duration in the nude and normal mice despite the failure of the former to mount a chlamydial antibody response. In contrast, 14 of 18 normal mice had developed a 4-fold or greater rise in the titre of IgG antibody 14 days after inoculation. A serum titre of 1:512 or greater was attained in 15 of these mice, and high titres persisted for 69 days or longer after inoculation. The numbers of polymorphonuclear leucocytes in vaginal smears from both normal and nude mice increased by 12 days after inoculation, indicating an inflammatory cell response. However, interpretation of the cellular response after the 40th day was difficult because of recommencement of the oestrous cycle. The results indicate that T lymphocytes and T-lymphocyte-dependent antibody have little effect on the course of the self-limited chlamydial genital infection.