ABSTRACTTo determine the ability of the major outer membrane protein (MOMP) to elicit cross-serovar protection, groups of mice were immunized by the intramuscular (i.m.) and subcutaneous (s.c.) routes with recombinant MOMP (rMOMP) fromChlamydia trachomatisserovars D (UW-3/Cx), E (Bour), or F (IC-Cal-3) orChlamydia muridarumstrain Nigg II using CpG-1826 and Montanide ISA 720 VG as adjuvants. Negative-control groups were immunized i.m. and s.c. withNeisseria gonorrhoeaerecombinant porin B (Ng-rPorB) or i.n. with Eagle's minimal essential medium (MEM-0). Following vaccination, the mice developed antibodies not only against the homologous serovar but also against heterologous serovars. The rMOMP-vaccinated animals also mounted cell-mediated immune responses as assessed by a lymphoproliferative assay. Four weeks after the last immunization, mice were challenged i.n. with 104inclusion-forming units (IFU) ofC. muridarum. The mice were weighed for 10 days and euthanized, and the number of IFU in their lungs was determined. At 10 days postinfection (p.i.), mice immunized with the rMOMP ofC. muridarumorC. trachomatisD, E, or F had lost 4%, 6%, 8%, and 8% of their initial body weight, respectively, significantly different from the negative-control groups (Ng-rPorB, 13%; MEM-0, 19%;P< 0.05). The median number of IFU recovered from the lungs of mice immunized withC. muridarumrMOMP was 0.13 × 106. The median number of IFU recovered from mice immunized with rMOMP from serovars D, E, and F were 0.38 × 106, 7.56 × 106, and 11.94 × 106IFU, respectively. All the rMOMP-immunized animals had significantly less IFU than theNg-rPorB (40 × 106)- or MEM-0 (70 × 106)-immunized mice (P< 0.05). In conclusion, vaccination with rMOMP can elicit protection against homologous and heterologousChlamydiaserovars.
Chlamydia muridarum Major Outer Membrane Protein-Specific Antibodies Inhibit In Vitro Infection but Enhance Pathology In Vivo
