Next generation sequencing reveals widespread trypanosome diversity and polyparasitism in marsupials from Western Australia.

Alan J Lymbery,R.C Andrew Thompson,Frances Brigg,Louise Pallant,Crystal Cooper,Alex W Gofton,Sarah Keatley,Amy Northover,Peta L Clode

doi:10.1016/j.ijppaw.2018.01.005

Abstract

In Western Australia a number of indigenous Trypanosoma spp. infect susceptible native marsupials, such as the woylie (Bettongia penicillata), brushtail possum (Trichosurus vulpecula), and chuditch (Dasyurus geoffroii). Two genotypes of Trypanosoma copemani (identified as G1 and G2) have been found in the woylie, and G2 has been implicated in the decline of this host species, making its presence of particular interest. Here we used targeted amplicon next generation sequencing (NGS) of the Trypanosoma 18S rDNA loci on 70 Trypanosoma-positive marsupial blood samples, to identify T. copemani genotypes and multiple Trypanosoma infections (polyparasitism) in woylies and cohabiting species in Western Australia. Polyparasitism with Trypanosoma spp. was found in 50% of the wildlife sampled, and within species diversity was high, with 85 zero-radius operational taxonomic units (ZOTUs) identified in nine putative parasite species. Trypanosoma copemani was assigned 17 ZOTUs and was identified in 80% of samples. The most abundant ZOTU isolated (63%) differed slightly from the published genotype of G1, and G2 was the second most abundant ZOTU (14%). Trypanosome diversity was significantly greater in woylies than in brushtail possums, and parasite community composition also differed significantly between these host species. One novel Trypanosoma spp. genotype (Trypanosoma sp. ANU2) was found in 20% of samples. A species of Crithidia was detected in a woylie, and two avian trypanosomes (Trypanosoma avium and Trypanosoma sp. AAT) were identified in woylies for the first time.

Highlights

Since Europeans arrived in Australia over 200 years ago, 30 native mammals have become extinct, with 30% of the surviving terrestrial mammalian population, threatened with extinction (Woinarski et al, 2015)
From the 70 blood samples that tested positive for trypanosomes from 56 wildlife hosts, genotypes from 85 different zero-radius operational taxonomic units (ZOTUs) were identified, which were assigned to nine species groups (Table 1, Fig. 1)
The most common trypanosome identified in the 56 blood samples was T. copemani with 17 unique ZOTUs in 52 individual hosts, including all three host species

Summary

Introduction

Since Europeans arrived in Australia over 200 years ago, 30 native mammals have become extinct, with 30% of the surviving terrestrial mammalian population (excluding bats), threatened with extinction (Woinarski et al, 2015). Once occupying a substantial portion of southern Australia, the woylie is confined to just three regions in the south west of Western Australia (WA) after experiencing a 90% population decline over seven years (Yeatman and Groom, 2012; Wayne et al, 2013). Two of the remaining three wild populations occur in the Upper Warren Region (UWR) in south west WA (Kingston and Perup) (Yeatman and Groom, 2012). (Botero et al, 2013; Thompson et al, 2013a, 2013b) Other susceptible marsupials such as the brushtail possum (Trichosurus vulpecula) and the near-threatened chuditch (Dasyurus geoffroii) share habitats with woylies and are susceptible to Trypanosoma spp. infection

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