Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2017

Novel insights to Sarcoptes scabiei mitochondrial genomes within Australian native animals (#127)

Tamieka Fraser 1 2 , Renfu Shao 2 , Michael Charleston 1 , Nick Fountain-Jones 3 , Alynn Martin 1 , Pam Whiteley 4 , Roz Holme 5 , Scott Carver 1 , Adam Polkinghorne 1
  1. University of Tasmania, Hobart, Tasmania, Australia
  2. GeneCology, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
  3. University of Minnesota, Minneapolis, Minnesota, United States of America
  4. Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
  5. Cedar Creek Wombat Rescue Inc. & Hospital, Cedar Creek, New South Wales, Australia

Introduction

Sarcoptes scabiei has important implications for wildlife conservation and animal and human health.  This mite has devastating effects on an Australian icon, the bare-nosed wombat, causing detrimental population decline and hindering the long-term survival of small subpopulations. There is an unresolved debate over the origins of sarcoptic mange in Australia, with the most consistent conclusion being that mange was introduced by settlers and their dogs. A shortage of mite genetic data from Australian wildlife means that these questions are unresolved, however.

Methods

Skin scrapings were obtained from a range of Australian marsupials that were confirmed to have sarcoptic mange; Victorian koalas (N=5) and wombats from New South Wales(N=2), Victoria (N=2) and Tasmania (N=3). Mites from an individual host was selected and subjected to DNA extractions for four long range overlapping PCRs targeting the whole mitochondrial genome (approx. 13800bp). The four PCR products were purified and pooled individually for each host and put through pair-end sequencing on a HiSeq4000. Assembly and annotation of the 12 mtDNA genomes was conducted with Geneious and ARWEN.

Results

Analysis of the resulting draft mtDNA genomes revealed that minor genetic differences exist between wombat, human and dog mite mitochondria, sharing between 96% and 99% genetic similarity, with each of the 12 new mtDNA genomes being unique. Phylogenetically, some wombat mites were more closely related to koala mites than to other wombat mites. The presence of putatively multiple evolutional linages may suggest multiple origins of mites in Australian marsupials. Furthermore, this study confirms COX1 to be the best gene target for global phylogenetic analysis, with a new gene target, CYTB, potentially suitable for fine-detailed epidemiological analysis within populations.  

Conclusion

The impacts of mange in Australian wildlife illustrates the greater importance of sarcoptic mange due to its continual increase in host range and global diversification. Further in-depth phylogenetic research, expanding host samples, will contribute valuable knowledge to understanding spillover of this mite.