Characterising venom toxins of veterinary importance in Australia

Several Australian invertebrates cause serious harm to pets and livestock through the production and delivery of potent venom toxins. Despite their economic importance, the mechanisms by which these toxins work are unknown. This project aims to elucidate the mechanism of action of toxins produced by two species of venomous invertebrates, the Australian paralysis tick Ixodes holocyclus and the Australian processionary caterpillar Ochrogaster lunifer, with a view to the development of strategies to limit their impact.

I. holocyclus is a major threat to our pets and livestock, affecting >10,000 dogs and numerous other animals each year, resulting in hundreds of animal deaths and massive veterinary costs. It is highly prevalent on the densely populated east coast, and it is the most common species of tick to parasitise pets and livestock in Australia. I. holocyclus injects saliva or venom containing paralytic neurotoxins that delay or prevent host detection and removal. A single tick will kill 99% of dogs if allowed to feed for more than three days, with a characteristic onset of paralysis on the fourth day, followed by limb paralysis, systemic and respiratory paralysis, and death if the tick is not removed. One group of disulphide-rich peptides, the holocyclotoxins (HCTXs), has been isolated from salivary gland extract and is proposed to constitute the relevant paralytic neurotoxins. However, the molecular mechanism by which HCTXs act is unknown.

The processionary caterpillar O. lunifer causes contact dermatitis and severe allergic reactions in mammals. The responsible structures are venom-filled urticating hairs that are tiny (~100 µm long), spear-shaped structures. These setae are also the causative agent of equine foetal loss syndrome (EAFL), a condition in which pregnant mares that ingest setae abort their foetuses. However, the function of O. lunifer venom toxins, and if they contribute to EAFL, is unknown.

This project would focus on determining the mode of action of either I. holocyclus or O. lunifer venom peptides, using techniques such as peptide synthesis or heterologous expression, electrophysiology, mass spectrometry, confocal microscopy, biolayer interferometry, and nuclear magnetic resonance.

The University of Queensland (UQ) has a strong and internationally focused research culture. UQ ranks well within the top 100 universities worldwide, measured through a number of major independent university rankings: the Academic Ranking of World Universities, Times Higher Education World University Rankings, US News Best Global Universities Rankings, QS World University Rankings and Performance Ranking of Scientific Papers for World Universities.

UQ is one of Australia’s most comprehensive universities, with one hundred percent of our research across all 22 broad fields rated either above (4) or well above (5) world standard in the 2018 Excellence in Research for Australia (ERA) exercise. Significantly, UQ was also assessed as being above or well above world standard across more specialised fields of research (93) than any other Australian university. In the nation’s 2018 Research Engagement and Impact assessment (EI2018), UQ was first amongst all Australian universities in the number of high and medium ratings across Engagement, Impact, and Approach to Impact, highlighting UQ’s commitment to translating research in all disciplines for the benefit of our wider society.

This project would take place in UQ's Institute for Molecular Bioscience (IMB), which was ranked as Australia’s #1 research institute in 2022 according to the Nature Index metric. Venom and peptide science is a key strength at IMB and UQ. This project will make use of numerous key infrastructure at UQ, including the IMB Sequencing Facility, Queensland Bioscience Precinct proteomics facility, Insectary and Animal Facilities, NMR spectrometers, Bunya high-performance computing cluster, and state-of-the-art fluorescent microscopes.