Andrew C Thompson

The genus Trypanosoma comprises numerous species of flagellated vector-borne protozoa that parasitise the blood and tissues of vertebrates. They are ubiquitous in terms of their geographical distribution and host range. In mammals, most species of Trypanosoma have been described from wildlife yet apart from their taxonomy, we know very little about the host parasite relationship, particularly those species in Australia. Most of what is known about their host parasite relationships, life history, and developmental biology has been obtained from studies on the two species that invade cells and infect humans - T. brucei and T. cruzi - species endemic in Africa and South America respectively, and which are major causes of disease and death in humans and domestic animals. T. brucei is the cause of sleeping sickness as a result of its association with the nervous system, whereas T. cruzi is the cause of Chagas disease that results in cardiac, neurological, and digestive disorders. Importantly, an Australian species - T. copemani G2 - has also been found to invade cells, thus demonstrating a pathogenic potential previously not associated with trypanosomes from Australia. Recently several new species of Trypanosoma in Australian marsupials (T. copemani (G1 & G2), T. vergrandis, and T. noyesi) have been characterised. These have varying affinities to T. cruzi, including surprisingly similar genetic relationships (e.g. close genetic link of T. noyesi and T. cruzi) and behavioural traits (e.g. cellular invasion by both T. copemani and T. cruzi). Such observations not only raise concerns about the impact of Australian trypanosomes on wildlife health and conservation but also in terms of biosecurity and human health given the potential for local transmission of imported cases of Chagas disease. Here we present correlative data across a range of length scales demonstrating the ongoing characterisation of several Trypanosoma spp. from Australian wildlife. In particular we have used live cell imaging to show host cell-pathogen interactions (Figure 1), scanning (SEM) (Figure 2) and transmission (TEM) (Figure 3) electron microscopy for structural analysis, and Slice and ViewTM focussed ion beam-scanning electron microscopy (FIB-SEM)(Figure 4) to begin to image key structural features (e.g. kinetoplast, flagellum) at high resolution in 3-dimensions. Together these data are i) providing a greater understanding of the pathogenic potential and host-parasite relationships of trypanosomes in Australian marsupials; ii) allowing for identification of biosecurity issues relating to potential local hosts and transmission of exotic species; and iii) generating information about the role of trypanosomes as a potential cause of disease in threatened and endangered Australian marsupials.