Evaluation of a Pmp18D vibro cholerae ghost vaccine against chlamydia abortus in mice (VET2P.1046)

Abstract

Abstract Chlamydia abortus (C. abortus) is an obligate intracellular pathogen that causes abortion in pigs and poses a zoonotic risk in pregnant women. Currently available attenuated and inactivated vaccines show marginal protective efficacy underlining the need for the development of effective vaccines. Recombinant proteins expressed on gram negative bacterial envelopes are known to induce protective immunity (Th1) without the need of any additional adjuvant. Pmp18D is a member of polymorphic outer membrane protein family of C.abortus. The PmpD protein of C. abortus is expressed throughout the chlamydial developmental cycle. Pmp protein family members are known to exhibit higher immunogenicity. In this study an evaluation of immune responses to Vibrio cholerae ghosts expressing Pmp18D(rVCG) was done in comparison to rPmp18D codelivered with either Flt3L or CpG. Mice were immunized 3 times intranasally 2 weeks apart .By day 14 post last immunization, the rVCG vaccine elicited significantly higher levels of antigen-specific IgG2a and IgA antibodies both in serum and in vaginal washes. Proliferative responses of mucosal (genital tract) as well as splenic (systemic) T cells were significantly higher in mice receiving rVCG vaccine.These results indicate that the rVCG-Pmp18D vaccine is capable of inducing antigen-specific cellular and humoral immune responses that may provide protective immunity against a live challenge infection with C.abortus.