Molecular evidence of Chlamydia pecorum and arthropod-associated Chlamydiae in an expanded range of marsupials

Delaney Burnard1, Wilhelmina M. Huston2, Jonathan K. Webb2, Martina Jelocnik1, Andrea Reiss3, Amber Gillett4, Sean Fitzgibbon5, Scott Carver6, Janine Carrucan7, Cheyne Flanagan8, Peter Timms1 & Adam Polkinghorne1

1Centre for Animal Health Innovation, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, 4556, Australia.
2School of Life Sciences, University of Technology Sydney, Ultimo, Sydney, 2007, Australia.
3Conservation Medicine Program, Murdoch University, Perth, 6150, Australia.
4Australia Zoo Wildlife Hospital, Steve Irwin Way, Beerwah, 4519, Australia.
5School of Agriculture and Food Sciences, University of Queensland, Brisbane, 4072, Australia.
6School of Biological Sciences, University of Tasmania, Hobart, 7001, Australia.
7North Queensland Wildlife Care Inc, 4814, Aitkenvale, Australia.
8Port Macquarie Koala Hospital, House Historic Site, Cnr Lord Street and Roto Place, Port Macquarie, New South Wales, 2444, Australia.

The order Chlamydiales are biphasic intracellular bacterial pathogens infecting humans and domesticated animals. Wildlife infections have also been reported, with the most studied example being Chlamydia pecorum infections in the koala, an iconic Australian marsupial. In koalas, molecular evidence suggests that spill-over from C. pecorum infected livestock imported into Australia may have had a historical or contemporary role. Despite preliminary evidence that other native Australian marsupials also carry C. pecorum, their potential as reservoirs of this pathogen and other Chlamydia-related bacteria (CRBs) has been understudied. Mucosal epithelial samples collected from over 200 native Australian marsupials of diferent species and geographic regions across Australia were PCR screened for Chlamydiales. Previously described and genetically distinct C. pecorum genotypes and a range of 16S rRNA genotypes sharing similarity to diferent CRBs in the broader Chlamydiales order were present. One 16S rRNA Chlamydiales genotype recently described in Australian ticks that parasitise native Australian marsupials was also identifed. This study provides further evidence that chlamydial infections are widespread in native fauna and that detailed investigations are required to understand the infuence these infections have on host species conservation, but also whether infection spill-over plays a role in their epidemiology.