A recombinant Chlamydia trachomatis MOMP vaccine elicits cross-serogroup protection in mice against vaginal shedding and infertility.

BACKGROUND: Chlamydia trachomatis (Ct) is the most common sexually transmitted bacterial pathogen worldwide. Here, we determined the ability of a Ct recombinant major outer membrane protein (rMOMP) vaccine to elicit cross-serogroup protection.

METHODS: Female C3H/HeN mice were vaccinated by mucosal and systemic routes with Ct serovar D (UW-3/Cx) rMOMP and challenged in the ovarian bursa with Ct serovars D (UW-3/Cx), D (UCI-96/Cx), E (IOL-43) or F (N.I.1). CpG-1826 and Montanide ISA 720 were used as adjuvants.

RESULTS: Immune responses following vaccination were more robust against the most closely related serovars. Following a genital challenge, as determined by number of mice with positive vaginal cultures, number of positive cultures, number of IFU recovered and number of days with positive cultures, mice challenged with Ct serovars of the same complex were protected but not those challenged with serovar F (N.I.1) from a different subcomplex. Females were caged with male mice. Based on fertility rates, number of embryos and hydrosalpinx formation, vaccinated mice were protected against challenges with serovars D (UW-3/Cx), D (UCI-96/Cx), E (IOL-43) but not F (N.I.1).

CONCLUSIONS: This is the first subunit vaccine that has been shown to protect mice against infection, pathology and infertility caused by different Ct serovars.