Conference Agenda

Session

CP21: Cells, Molecules & Genes 4 - 15 min talks

Time:

Thursday, 02/July/2026:

3:30pm - 4:00pm

Session Chair: Andrew Walker, The University of Queensland
Session Chair: Natasha Sharma, The University of Melbourne

Location: Lecture Theatre 1

Boulevard Room 3

Presentations

The chromosome-scale assembly of the Australian Paralysis Tick, Ixodes holocyclus

Amrita Vijay¹, Alexander Gofton², Quentin Gouil³, Shilpa Kapoor⁴, Swapnil Tichkule^1,5, Balu Balan¹, Louise Baker¹, Stefano Gaiarsa⁶, Clare A Anstead⁴, Ala Tabor⁷, Nathan Lo⁸, Stephen Barker⁹, Jan Riemer¹⁰, Fabrizia Stavru¹¹, Davide Sassera^12,13, Peter Czabotar¹, Tony Papenfuss¹, Aaron Jex^1,4

1: Walter and Eliza Hall Institute, Department of Medical Biology, The University of Melbourne, Victoria, Australia; 2: Zoonotic & Arboviral pathogens, Health & Biosecurity, CSIRO, Canberra, Australia; 3: Olivia Newton-John Cancer Research Institute, Australia; 4: Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Victoria, Australia; 5: Icahn School of Medicine at Mount Sinai, USA; 6: Microbiology and Virology unit at Policlinico San Matteo, Fondazione IRCCS, Pavia, Province of Pavia, Italy; 7: The University of Queensland, Queensland Alliance for Agriculture & Food Innovation, St Lucia, Queensland, Australia; 8: School of Life and Environmental Sciences, The University of Sydney, New South Wales; 9: School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland, Australia; 10: Department for Chemistry, Institute for Biochemistry, University of Cologne, Cologne, Germany; 11: Deceased:Fabrizia Stavru; 12: Department of Biology and Biotechnology, University of Pavia, Pavia, Italy; 13: Fondazione IRCCS Policlinico San Matteo, Pavia, Italy

Ixodes holocyclus (the Australian eastern paralysis tick) is a medically and veterinary important ectoparasite that produces potent neurotoxins, holocyclotoxins, causing rapidly ascending flaccid paralysis in companion animals, livestock and humans, often fatally. Despite its importance, the molecular basis of toxin production, host specificity and survival remains poorly understood because genomic and transcriptomic resources are limited. We generated the first chromosomal-scale genome for I. holocyclus using Oxford Nanopore long reads, Illumina short reads and Hi-C, and annotated genes with a hybrid de novo transcriptome, resolving alternative splicing with long- and short-read alignments. We scanned UTRs and upstream regions of complete genes for conserved regulatory motifs, including putative promoters. Comparative genomics, including synteny and phylogenomic placement, was performed, and ticks from 32 eastern Australian sites were sequenced to examine genomic diversity and its links to ecological adaptation and vector capacity. The 1.9 Gb assembly contains 13 chromosome-level scaffolds, 66% repetitive elements and 93.3% BUSCO completeness. Annotation identified a high-confidence gene set including protein-coding genes. Synteny with I. scapularis and I. ricinus revealed conserved supergene blocks. Together, these resources advance tick biology and support targeted control strategies against tick-borne diseases.

Long-read–supported gene modelling illuminates feeding, immune, and developmental biology in the European castor bean tick, Ixodes ricinus.

Amrita Vijay¹, Balu Balan¹, Louise Baker¹, Stefano Gaiarsa², Quentin Gouil³, Pradip Roy¹, Alexander Gofton⁴, Alessandra Cafiso⁵, Ala Tabor⁶, Nathan Lo⁷, Olivier Plantard⁸, Jan Riemer⁹, Fabrizia Stavru¹⁰, Clare A Anstead¹¹, Peter Czabotar¹, Tony Papenfuss¹, Davide Sassera^12,13, Aaron Jex^1,11

1: Walter and Eliza Hall Institute, Department of Medical Biology, The University of Melbourne, Victoria, Australia; 2: Department of Microbiology & Virology, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; 3: Olivia Newton-John Cancer Research Institute, Victoria, Australia; 4: CSIRO, Health and Biosecurity, Brisbane, Queensland, Australia; 5: Department of Veterinary Medicine and Animal Sciences, University of Milan, Lodi, Italy; 6: The University of Queensland, Queensland Alliance for Agriculture & Food Innovation, St Lucia, Queensland, Australia; 7: School of Life and Environmental Sciences, The University of Sydney, New South Wales; 8: Oniris, INRAE, BIOEPAR, 44300, Nantes, France; 9: Department for Chemistry, Institute for Biochemistry, University of Cologne, Cologne, Germany; 10: Deceased: Fabrizia Stavru; 11: Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Victoria, Australia; 12: Department of Biology and Biotechnology, University of Pavia, Pavia, Italy; 13: Fondazione IRCCS Policlinico San Matteo, Pavia, Italy

The European castor bean tick, Ixodes ricinus, is a major blood-feeding ectoparasite and vector of Lyme disease, tick-borne encephalitis and babesiosis. Reducing tick-borne disease requires an improved understanding of tick molecular biology across tissues and feeding stages. We applied long-read, full-length mRNA sequencing to refine gene models in the published I. ricinus genome and to profile salivary glands and ovaries across blood-feeding phases. Curated functional annotation was used to interpret pathways central to ectoparasitism. We defined 30,454 gene models, including 28,515 protein-coding genes. Functional curation provided insight into chemosensation, hematophagy, immune tolerance, reproduction and fecundity. Salivary glands showed feeding-associated metabolic rewiring, vesicle biogenesis, and secretome remodelling, consistent with anti-clotting, vasodilatory, anti-inflammatory, and immunomodulatory functions that counter host defences. Ovarian transcriptomes revealed early reprogramming of cell-fate pathways, cytoskeletal organisation, extracellular matrix dynamics, and immune regulation, consistent with priming for fertilisation and embryogenesis. This transcriptomic blueprint provides a high-resolution annotation resource for the I. ricinus genome and delineates tissue- and stage-specific programmes that underpin feeding and reproduction, providing a platform for mechanistic studies and improved tick control strategies.