Molecular characterization of native Australian trypanosomes in quokka (Setonix brachyurus) populations from Western Australia

•Molecular characterization of Trypanosoma copemani at 2 loci•Identification of distinct genotypes within T. copemani•Mixed infections with other trypanosome species identified•T. copemani genotype A may be pathogenic.•Trypanosoma vegrandis is a species complex.

The quokka, Setonix brachyurus, is a vulnerable, small marsupial endemic to Western Australia. Blood samples were collected from quokkas from three different geographical locations; Two Peoples Bay, Bald Island and Rottnest Island. The overall prevalence of trypanosomes by nested PCR at the 18S ribosomal RNA gene was 57.3% (63/110) with prevalences of 91.4%, 85.3% and 4.9% respectively for Two Peoples Bay, Bald Island and Rottnest Island. Phylogenetic analysis conducted on 47 18S PCR positives identified two Trypanosoma copemani genotypes, with T. copemani genotype B, the most prevalent genotype infecting quokka populations from the three locations with an overall prevalence of 51.8% (24/47) compared to 34% for T. copemani genotype A (16/47). The overall prevalence of mixed T. copemani genotype A and B infections was 14.9% (7/47). Phylogenetic analysis of 26 quokka isolates at the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locus, largely supported the 18S analysis but identified a mixed infection in one quokka isolate (Q4112-4117 from Two Peoples Bay). T. copemani genotype B has previously only been isolated from quokkas and the Gilbert's potoroo whereas T. copemani genotype A has a wide host range and may be pathogenic. Further work is required to determine the clinical impact of T. copemani on marsupial populations.

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