Novel Chlamydiales genotypes identified in ticks from Australian wildlife
Delaney Burnard1, Haylee Weaver2, Amber Gillett3, Joanne Loader4, Cheyne Flanagan5 and Adam Polkinghorne1*
1Centre for Animal Health Innovation, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Burnard et al. Parasites & Vectors (2017) 10:46 Page 8 of 10 Australia.
2Australian Government, Department of Environment and Energy, Australian Biological Resources Study, GPO Box 787, Canberra, ACT 2601, Australia.
3Australia Zoo Wildlife Hospital, Steve Irwin Way, Beerwah, QLD 4519, Australia.
4Endeavour Veterinary Ecology Pty Ltd, 1695 Pumicestone Rd, Toorbul, QLD 4510, Australia.
5Port Macquarie Koala Hospital, Roto House Historic Site, Cnr Lord Street and Roto Place, Port Macquarie 2444, NSW, Australia.
Background Members of the order Chlamydiales are known for their potential as human and veterinary bacterial pathogens. Despite this recognition, epidemiological factors such as routes of transmission are yet to be fully defined. Ticks are well known vectors for many other infections with several reports recently describing the presence of bacteria in the orderChlamydiales in these arthropods. Australian wildlife are hosts to an extensive range of tick species. Evidence is also growing that the marsupial hosts these ticks parasitise can also be infected by a number of bacteria in the orderChlamydiales, with at least one species, Chlamydia pecorum, posing a significant conservation threat. In the current study, we investigated the presence and identity ofChlamydiales in 438 ixodid ticks parasitizing wildlife in Australia by screening with a pan-Chlamydiales specific targeting the 16S rRNA gene.
Results Pan-Chlamydiales specific PCR assays confirmed the common presence of Chlamydiales in Australian ticks parasitising a range of native wildlife. Interestingly, we did not detect anyChlamydiaceae, including C. pecorum, the ubiquitous pathogen of the koala. Instead, theChlamydiales diversity that could be resolved indicated that Australian ticks carry at least six novelChlamydiales genotypes. Phylogenetic analysis of the 16S rRNA sequences (663 bp) of these novelChlamydiales suggests that three of these genotypes are associated with the Simkaniaceae and putatively belong to three distinct novel strains ofFritschea spp. and three genotypes are related to the “Ca. Rhabdochlamydiaceae” and putatively belong to a novel genus, Rhabdochlamydia species and strain, respectively.
Conclusions Sequence results suggest Australian wildlife ticks harbour a range of unique Chlamydiales bacteria that belong to families previously identified in a range of arthropod species. The results of this work also suggest that it is unlikely that arthropods act as vectors of pathogenic members of the familyChlamydiaceae, including C. pecorum, in Australian wildlife. The biology of novelChlamydiales identified in arthropods remain unknown. The pathogenic role of the novelChlamydiales identified in this study and the role that ticks may play in their transmission needs to be explored further.