Induction of a Protective Immune Response Against Swine Chlamydophila abortus Infection in Mice Following Co‐Vaccination of omp‐1 DNA with Recombinant MOMP

Abstract

Chlamydophila abortus is the causative agent of abortion in pigs and pregnant women. Seroconversion rates were arranged from 11% to 80% in piglets and sows in China. These very high rates illustrate the scale of the problem in China and highlight the urgent need for the development of a C. abortus vaccine. An efficacious anti-chlamydial vaccine should induce not only strong mucosal and systemic T-helper type 1 (Th1) immune response but also give a humoral response that enhances Th1 activation following infection. In order to evaluate an active immune response of a combination of the major outer membrane protein (MOMP) DNA- and protein-based vaccines, 54 BALB/c mice were randomly assigned to six groups and inoculated intramuscularly with: (i) 100 microg pcDNA::MOMP, (ii) 10 microg r-MOMP, (iii) primed with 100 microg pcDNA::MOMP and boosted with 10 microg r-MOMP, (iv) primed-boosted with a combination of pcDNA::MOMP and r-MOMP simultaneously, (v) live-attenuated 1B vaccine, (vi) 100 microg pcDNA3.1 vector. All animals were vaccinated two times at 14 days intervals. Results showed that mice given DNA and r-MOMP induced higher antibody levels, higher T cells proliferation and an elevated level of chlamydial clearance in spleen, which was equivalent to the clearance of 1B vaccine. Mice administrated the DNA-primed/MOMP-boosted approach elicited moderate antibody levels, less T-lymphocyte proliferation and lower chlamydial clearance as compared with 1B vaccine. Co-immunization with DNA- and r-MOMP vaccine may provide novel ways for active immunization strategy against swine C. abortus.