Conference Agenda

Parasites and their hosts engage in an ‘evolutionary arms race.’ As a parasite evolved tools to infect its host, the host will develop adaptations to evade infection. Microbiomes may also play key roles in the arms race between the two antagonists. We characterised the entire microbiome of parasite-host interactions, using the New Zealand native hairworms Gordius paranensis and Euchordodes nigromaculatus and their cave wētā hosts (Rhaphidophoridae) to investigate host and parasite microbiome overlap. Infected wētā, uninfected wētā, juvenile hairworms, and free-living mature hairworms all have microbiomes including viruses, bacteria, fungi, archaea and protists. We found that parasites harbour their own unique microbial taxa, in addition to microbes shared with infected wētā but not with uninfected wētā. This suggests hairworms do not rely on their host to develop a microbiome. As hairworms progress through their life stages, they exhibit a core microbiome; however, microbial community composition varies significantly across life stages, suggesting the environment has a significant effect on the parasite’s microbiome. Therefore, hairworm microbiomes are dynamic across the life cycle and modulated by the host and environment. The hairworm's diverse microbiome raises the intriguing possibility that its symbiotic microbes contribute to the iconic host manipulation (suicidal water-jumping) associated with hairworms.

Toxoplasma gondii is a zoonotic parasite with a global distribution that can infect a wide range of warm-blooded hosts. This study investigated, for the first time, the seroprevalence and genetic variability of T. gondii in red foxes (Vulpes vulpes) from Victoria, Australia. Animals from both regional Victoria and the metropolitan Melbourne area were sourced from trappers and shooters involved in pest control. Sera were screened for anti-T. gondii IgG antibodies using a modified agglutination test, and tissue samples were tested using a qPCR assay targeting the 529 bp repeated element. qPCR positive samples were genotyped using a five-marker (L358, 5’SAG2, 3’SAG2, c22-8, GRA6) polymerase chain reaction-restriction fragment length polymorphism protocol. Anti-T. gondii antibodies were detected in 38.9% (30/77) of foxes, and parasite DNA was identified in 23.4% (18/77) of animals. Genotyping revealed a predominance of T. gondii clonal Type II whereas two isolates showed new alleles attributable to Type II-like genotypes. These findings suggest that Australian red foxes are frequently exposed to T. gondii and may play an important role as epidemiological sentinels to assess the circulation of T. gondii in the Australian environment, with implications for both wildlife conservation and public health.

Integrating traditional morphology with three-dimensional imaging and genetic data supports robust species hypotheses. The paramphistomoid fauna of Australian macropodids is poorly characterised, with two recognised genera, Gemellicotyle and Macropotrema, each containing a single species. Their conical form hampers morphological study, and no molecular data exists, making them ideal candidates for integrative taxonomy. This study describes Gemellicotyle sp. nov. from the caecum of the western grey kangaroo, Macropus fuliginosus. Whole-mount microscopy, serial histology, and X-ray microcomputed tomography (microCT) were combined to generate 3D reconstructions and printed models, enabling characterisation of internal and external morphology. These datasets were integrated with mitochondrial genome and nuclear ribosomal sequence data obtained using long-read sequencing. Gemellicotyle sp. nov. differs from G. wallabicola by lacking a central acetabular protuberance, having simple rather than sinuous caeca, and possessing more extensive vitellaria. MicroCT reconstructions and 3D models revealed 100 acetabular projections composed of radial muscle fibres, and a complex of lymphatic channels surrounding the acetabulum. This integrative approach refines species delineation and uncovers new knowledge on an Australian endemic paramphistome that depend on freshwater snail intermediate hosts to complete its lifecycle. This species may already be extinct due to changes in climate and habitats.