Induction of a protective immune response against swine Chlamydophila abortus infection in mice following co-vaccination of omp-1 DNA with recombinant MOMP

Cellular Basis for the Enhanced Efficacy of the Fms-Like Tyrosine Kinase 3 Ligand (FL) Adjuvanted VCG-Based Chlamydia abortus Vaccine

Efficacious vaccines are needed to control genital chlamydial diseases in humans and the veterinary industry. We previously reported a C. abortus (Cab) vaccine comprising recombinant Vibrio cholerae ghosts (rVCG) expressing the conserved and immunogenic N-terminal region of the Cab polymorphic membrane protein D (rVCG-Pmp18.1) protein that protected mice against intravaginal challenge. In this study, we investigated the immunomodulatory effect of the hematopoietic progenitor activator cytokine, Fms-like tyrosine kinase 3-ligand (FL) when co-administered with the rVCG-Pmp18.1 vaccine as a strategy to enhance the protective efficacy and the potential mechanism of immunomodulation. Groups of female C57BL/6J mice were immunized and boosted twice intranasally (IN) with rVCG-PmpD18.1 with and without FL or purified rPmp18.1 or rVCG-gD2 (antigen control) or PBS (medium) per mouse. The results revealed that co-administration of the vaccine with FL enhanced antigen-specific cellular and humoral immune responses and protected against live Cab genital infection. Comparative analysis of immune cell phenotypes infiltrating mucosal and systemic immune inductive tissue sites following immunization revealed that co-administration of rVCG-Pmp18.1 with FL significantly enhanced the number of macrophages, dendritic and NK cells, γδ and NK T cells in the spleen (systemic) and iliac lymph nodes (ILN) draining the genital tract (mucosal) tissues compared to rVCG-Pmp18.1 alone. Furthermore, FL enhanced monocyte infiltration in the ILN, while CD19+ B cells and CD4+ T cells were enhanced in the spleen. These results indicate that the immunomodulatory effect of FL is associated with its ability to mobilize innate immune cells and subsequent activation of robust antigen-specific immune effectors in mucosal and systemic lymphoid tissues.

Examination of the in vivo immune response elicited by Chlamydia psittaci in chickens

It has since long been reported that Chlamydia psittaci is endemic in the poultry industry in Belgium as well as in other European Countries. This can lead to major economic losses because of a lowered egg production, higher mortality and carcass condemnation. Nowadays, expensive antibiotic treatments are necessary to reduce mortality rate but this can lead to antibiotic resistance. Moreover, C. psittaci can easily be transmitted from birds to humans through the inhalation of pathogen-containing aerosols derived from feces and eye and nostril secretions. Therefore, the need for an efficient vaccine against C. psittaci is augmenting. However, more research is needed to develop such a vaccine. Knowledge on the immune mechanisms of C. psittaci infections is crucial to understand the pathogenesis of, and immunity to this zoonotic pathogen and to act as a basis for vaccination studies. This study has investigated the in vivo immune response evoked by C. psittaci in his natural host, the chicken. Excretion of C. psittaci, chlamydial antibody detection in sera, blood immune cells and the mRNA expression levels of different cytokines, chemokines and one Toll-like receptor were investigated in different organs (conchae, lungs, airsacs, harderian gland, bursa fabricius and spleen) at different time points post infection (6 h, 24 h, 48 h, 4 d, 6d, 8 d, 10 d, 14 d and 21 d). A higher frequency of cytotoxic CD8(+) T cells and monocytes/macrophages expressing the MHC II molecule were observed in the infected group. Several cytokines and chemokines are significantly upregulated during infection but remarkably also significantly downregulated, especially at late time points. Furthermore, the only Toll-like receptor investigated, TLR4, was also significant upregulated in several organs. This study can contribute on the elucidation on how C. psittaci interact with his host, leading to the developing of targets for effective vaccination and therapeutic strategies for infection.

Evaluation of an ompA-based phage-mediated DNA vaccine against Chlamydia abortus in piglets

Chlamydia abortus (C. abortus) is an obligate intracellular pathogen that causes abortion in pigs and poses a zoonotic risk in pregnant women. Although attenuated and inactivated vaccines are available, they do not provide complete protection in animals underlining the need to develop new vaccines. In this study, we tested the hypothesis that intramuscular immunization with an ompA-based phage-mediated DNA chlamydial vaccine candidate will induce significant antigen-specific cellular and humoral immune responses. Thus, groups of piglets (five per group) were immunized intramuscularly with the phage-MOMP vaccine (λ-MOMP) or a commercial live-attenuated vaccine (1B vaccine) or a GFP-expressing phage (λ-GFP) or phosphate buffered saline (PBS) (control) and antigen-specific cell-mediated and humoral immune responses were evaluated. By day 63 post-immunization, the λ-MOMP vaccine elicited significantly higher (P<0.05) levels of antigen-specific serum IgG antibody responses than the 1B vaccine or control did. Also, piglets immunized with λ-MOMP vaccine had significantly higher (P<0.05) MOMP-specific lymphocyte proliferative responses compared to those immunized with the 1B vaccine or control. Furthermore, the total T-cell numbers (CD3+) and the proportion of CD4+ and CD8+ T-cell subsets as well as the ratio of CD4+/CD8+ T cells elicited following immunization were comparable between the λ-MOMP- and 1B-vaccinated animals on both days 63 and 70. Interestingly, although the proportion of CD3+CD4-CD8- double negative T cells on day 63 was significantly higher (P<0.05) in the 1B vaccine group compared to the λ-MOMP-immunized group, there was a significant decrease in the proportion of this T-cell population on day 70 in the 1B compared to the λ-MOMP vaccinated group. These results indicate that the λ-MOMP DNA 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.

Chlamydiaceae infections in pig

Chlamydiaceae are Gram-negative obligate intracellular bacteria. They are responsible for a broad range of diseases in animals and humans. In pigs, Chlamydia suis, Chlamydia abortus, Chlamydia pecorum and Chlamydia psittaci have been isolated. Chlamydiaceae infections in pigs are associated with different pathologies such as conjunctivitis, pneumonia, pericarditis, polyarthritis, polyserositis, pseudo-membranous or necrotizing enteritis, periparturient dysgalactiae syndrome, vaginal discharge, return to oestrus, abortion, mummification, delivery of weak piglets, increased perinatal and neonatal mortality and inferior semen quality, orchitis, epididymitis and urethritis in boars. However, Chlamydiaceae are still considered as non-important pathogens because reports of porcine chlamydiosis are rare. Furthermore, Chlamydiaceae infections are often unnoticed because tests for Chlamydiaceae are not routinely performed in all veterinary diagnostic laboratories and Chlamydiaceae are often found in association with other pathogens, which are sometimes more easily to detect. However, recent studies have demonstrated that Chlamydiaceae infections in breeding sows, boars and piglets occur more often than thought and are economically important. This paper presents an overview on: the taxonomy of Chlamydiaceae occurring in pigs, diagnostic considerations, epidemiology and pathology of infections with Chlamydiaceae in pigs, public health significance and finally on prevention and treatment of Chlamydiaceae infections in pigs.

Zoonotic potential of Chlamydophila

The purpose of this article is to present the diseases induced in humans and animals by the different species of Chlamydophila, after providing an overview on the history of these infectious agents and their taxonomy. The route of transmission and the available methods for prevention and control in the different animal species are reviewed.