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C5 Comprehensive molecular and proteomic cyathostomin species delineation (v. Samson-Himmelstjerna/Krücken)

Research Group: Institute for Parasitology and Tropical Veterinary Medicine
Address: Freie Universität Berlin, Centre for Infection Medicine,
Robert-von-Ostertag-Str. 7-13, 14163 Berlin
Supervisor: Professor Dr. Georg v. Samson-Himmelstjerna / PD Dr. Jürgen Krücken
Doctoral Researcher: Christina Bredtmann

Project Description     

In wild and domestic horses cyathostomins reside as larval stages in the mucosa and as late larval and adult parasites in the lumen of the large intestine. Due to their ubiquitous, worldwide prevalence and potentially lethal pathogenicity, they are considered the most important equine parasites. This group consists of 50 species classified in 14 genera and usually multispecies-infections with of often more than 15 species are found. This unique level of complexity of co-infection poses intriguing, still unaddressed questions concerning species inter-dependencies and parasite community structuring. Neither taxonomy nor clinical relevance of cyathostomin multispecies-infections nor the impact of anthelmintic treatment on population composition and genetics are understood. Additionally, anthelmintic resistance (AR) has evolved globally as a major problem concerning cyathostomin treatment and control in farmed horses. Our understanding of the mechanisms of AR is very limited. Only for a few cyathostomin species, evidence for the involvement of specific amino acid changes in the β-tubulin isotype 1 gene in benzimidazole resistance has been established. The study of species complexity and of mechanisms of AR in cyathostomins is hampered by the lack of reliable identification. Currently, identification and differentiation are primarily based on microscopic examination, using often faint morphological characteristics of adults, while larvae and eggs are indistinguishable. Furthermore, there is molecular evidence for cryptic species complexes. Little is known about species specific pathogenicity, the unique feature of co-infections, host-parasite adaptation and the impact of domestication. To address these research issues, an improved rapid, reliable and efficient species identification approach is needed. We have conducted numerous studies concerning diagnostics, species composition, mechanism/prevalence of AR in cyathostomins and established a substantial cyathostomin sample bank and gene sequence data. We developed molecular tools to differentiate closely related cyathostomins and methods for analysis of AR. Our hypothesis is that novel molecular and proteomic approaches will lead to robust genetic cyathostomin-species delineation. For species identification and multi-locus phylogenetic analyses, ribosomal (internal- and intergenic-spacers) and mitochondrial (NADH reductase, cytochrome oxidase, control region) gene regions will be obtained for each worm. Protein samples will be prepared using adult and also egg and larval stages and species-specific spectra will be elucidated for equine cyathostomins using matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI TOF MS). The respective molecular and proteomic data will be comparatively analysed using bioinformatics approaches. The application of the resultant cyathostomin database will be evaluated using adult, larval and egg stages in representative numbers of natural infections from domestic and wild horse (e.g., Dülmener, Liebenthaler and Przewalski horses, zebras) populations.

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