Reduction of Chlamydia pecorum and Koala Retrovirus subtype B expression in wild koalas vaccinated with novel peptide and peptide/recombinant protein formulations.

Koalas are an endangered species under threat of extinction from several factors, including infections agents. Chlamydia pecorum infection results in morbidity and mortality from ocular and urogenital diseases while Koala Retrovirus (KoRV) infection has been linked to increased rates of cancer and chlamydiosis. Both C. pecorum and KoRV are endemic in many wild Australian koala populations, with limited treatment options available. Fortunately, vaccines for these pathogens are under development and have generated effective immune responses in multiple trials. The current study aimed to improve vaccine formulations by testing a novel peptide version of the Chlamydia vaccine and a combination Chlamydia - KoRV vaccine. Utilising a monitored wild population in Southeast Queensland, this trial followed koalas given either a 'Chlamydia only' vaccine (utilising four peptides from the chlamydial Major Outer Membrane Protein, MOMP), a combination 'Chlamydia and KoRV' vaccine (comprised of the chlamydial peptides plus a KoRV recombinant envelope protein (rEnv)) or no treatment. Clinical observations, C. pecorum and KoRV gene expression, serum IgG, and mucosal immune gene expression were assessed over a 17-month period. Overall, both vaccine formulations resulted in a decrease in chlamydiosis mortality, with decreases in C. pecorum, CD4, CD8ß and IL-17A gene expression observed. In addition, the combination vaccine group also showed an increase in anti-KoRV IgG production that corresponded to a decrease in detected KoRV-B expression. While these results are favourable, the chlamydial peptide vaccine did not appear to outperform the established recombinant chlamydial vaccine and suggests that a combination vaccine formulated with recombinant MOMP plus KoRV rEnv could capitalize on the demonstrated benefits of both for the betterment of koalas into the future.

LONEPINELLA SP. ISOLATED FROM WOUND INFECTIONS OF KOALAS.

We describe two cases of wound infections of koalas (Phascolarctos cinereus), one wild and one captive, in which Lonepinella-like organisms were involved. The wild adult koala was captured with bite wound injuries, as part of a koala population management program in Queensland, Australia. In both cases, there was evidence of physical trauma causing the initial wound. The captive koala suffered injury from the cage wire, and the wild koala had injuries suggestive of intermale fighting. Gram-negative bacteria isolated from both cases proved to be challenging to identify using routine diagnostic tests. The wound in the captive koala yielded a pure culture of an organism shown by whole genome sequence (WGS) analysis to be a member of the genus Lonepinella, but not a member of the only formally described species, L. koalarum. The wound of the wild koala yielded a mixed culture of Citrobacter koseri, Enterobacter cloacae and an organism shown by WGS analysis to be Lonepinella, but again not Lonepinella koalarum. Both cases were difficult to treat; the captive koala eventually had to have the phalanges amputated, and the wild koala required removal of the affected claw. The two Lonepinella isolates from these cases have a close relationship to an isolate from a human wound caused by a koala bite and may represent a novel species within the genus Lonepinella. Wound infections in koalas linked to Lonepinella have not been reported previously. Wildlife veterinarians need to be aware of the potential presence of Lonepinella-like organisms when dealing with wound infections in koalas, and the inability of commercial kits and systems to correctly identify the isolates.