Characterization of bare-nosed wombat immune gene responses to sarcoptic mange

Sarcoptic mange is caused by a parasitic mite and has been reported to infect a large number of mammals worldwide. This mite has devastating effects on an Australian icon; the bare-nosed wombat, causing skin irritation, severe... [ view full abstract ]

Sarcoptic mange is caused by a parasitic mite and has been reported to infect a large number of mammals worldwide. This mite has devastating effects on an Australian icon; the bare-nosed wombat, causing skin irritation, severe pain, secondary infections, restricting eyesight and resulting in detrimental population decline hindering long term survival of small subpopulations. Very little is currently known about the bare-nosed wombat immune response to mange. Assessing key immunological genes across different stages of mange may identify the mechanisms by which the immune system combats this infestation. In the absence of genomic information for this species, this study aimed to characterize wombat immune genes and develop assays to investigate their role in mange pathogenesis. Studies in other hosts have revealed that IL4, IL17a, TNFa, INFy, and IL10 play key roles in the pathogenesis of sarcoptic mange. Sequence homology between related marsupial species was used to amplify and sequence these five genes in the wombat. Once sequenced they were evaluated for genetic comparisons against other marsupials, eutherians and other species. As expected, sequence similarity and subsequent phylogenetic analyses revealed that wombat cytokine sequences cluster together with other marsupial cytokine gene sequences. Closest sequence similarities were to the koala with gene sequences sharing between 93% to 98% sequence similarity. IL10 was the most dissimilar of the cytokine gene sequences examined. These sequences were used to develop wombat-specific cytokine gene quantitative PCRs for immune analysis studies of bare-nosed wombats affected with mange. With the lack of the bare-nosed wombat transcriptome, preliminary sequence comparison reveals that the wombat immune system shares similarity to other marsupials. Comparison of cytokine responses will assist us in understanding the pathogenesis of this debilitating disease and to evaluate the efficacy of treatment options for this iconic marsupial.