12 months), with changes categorized into bands as either, decreasing, stable or increasing (qPCR -100, -99C99, and 100 copies/L respectively). 30 animals did not receive any vaccine and acted Rabbit Polyclonal to Trk C (phospho-Tyr516) as comparison controls. Animals accepted into this study were either uninfected (PCR negative) at time of initial vaccination, or infected (positive) at either urogenital (UGT) and/or ocular sites (Oc), but with no clinical signs of chlamydial disease. All koalas were vaccinated / sampled and then re-released into their natural habitat before re-capturing and re-sampling at 6 and 12 months. All vaccinated koalas produced a strong immune response to the vaccine, as indicated by high titres of specific plasma antibodies. The incidence of new infections in vaccinated koalas over the 12-month period post-vaccination was slightly less than koalas in the control group, however, this was not statistically significant. Importantly though, the vaccine was able to significantly reduce the infectious load in animals that were positive at the time of vaccination. This effect was evident at both the Oc and UGT sites and was stronger at 6 months than at 12 URMC-099 months post-vaccination. Finally, the vaccine was also able to reduce the number of animals that progressed to disease during the 12-month period. While the sample sizes were small (statistically speaking), results were nonetheless striking. This study highlights the potential for successful development of a vaccine for koalas in a wild setting. Introduction Infections by the intracellular bacterium contribute to significant morbidity and mortality in the koala (vaccine [4C9]. Based on studies which have shown efficacy in animal models (reviewed in Farris and Morrison ), the primary component of the vaccine has been the recombinant proteins derived from the chlamydial Major Outer Membrane Protein (rMOMP). rMOMP is highly immunogenic in humans and animals and has been studied in detail as a vaccine candidate. In the initial studies utilizing this vaccine antigen adjuvanted with an immune stimulating complex, we have shown that this prototype chlamydial vaccine (i) induces long-lasting specific humoral and cell-mediated immune responses in vaccinated koalas ; (ii) induces an immune response that can recognize genetically distinct strains, a capability that natural infection does not appear to have ; (iii) induces the production of specific antibodies that are effective in neutralizing ; and (iv) does not have any apparent deleterious effects on the health of vaccine within one free-ranging population in South-East Queensland (SEQ), Australia. Vaccinated and control cohorts of animals were then released, monitored for a period of 12 months, and recaptured periodically to compare a range of health parameters between the two groups. Materials and Methods MOMP recombinant preparation Purified URMC-099 MOMP from three koala genotypes (A, F and G) were used as previously described by Kollipara et al. . Animals and Immunizations Animals included URMC-099 in the study (n = 60) were part of a larger population-wide study by the Queensland Government Department of Transport and Main Roads (as part of the Moreton Bay Rail Link project), conducted between 2012 and 2015 in the Moreton Bay Region, Queensland, Australia. Criteria for inclusion into the study were animals of breeding age ( 1 year) of either sex, with no clinical signs of chlamydial disease, as assessed during the initial capture event by qualified wildlife veterinarians. Animals were randomly assigned to either the vaccinated or control (non-vaccinated) group at initial capture. The vaccinated group (n = 30) received a three-dose regime of the vaccine via the sub-cutaneous route, given at one-month intervals, consisting of the three URMC-099 rMOMP proteins as the antigens (50g each of MOMP-G, MOMP-A, and MOMP-F) and an Immunostimulating complex adjuvant (50g, ISC, Zoetis Australia ). Following a detailed veterinary health assessment, animals were released with a radio collar or anklet for tracking (Sirtrack). Animals were re-captured URMC-099 at 1 month, 2 months, 6 months, and 12 months for the purpose of (i) additional vaccinations for the vaccine cohort animals only (1 month and 2 months) or (ii) detailed health checks and sampling (2, 6 and 12 months). While 30 animals were originally recruited into each group,.