Genetic exchange and sub-structuring in Theileria annulata populations

Weir, W. , Ben-Miled, L., Karagenc, T., Katzer, F., Darghouth, M., Shiels, B. and Tait, A. (2007) Genetic exchange and sub-structuring in Theileria annulata populations. Molecular and Biochemical Parasitology, 154(2), pp. 170-180. (doi: 10.1016/j.molbiopara.2007.04.015) (PMID:17540465)

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Tropical theileriosis, caused by the tick-transmitted protozoan Theileria annulata, is a major disease of cattle in many regions of the developing world. Development and deployment of current and novel control strategies should take into account the potential diversity of parasite populations and therefore it is important that the nature and basis for this genetic variation is investigated and quantified. The recently completed genome sequence of T. annulata provided an opportunity to develop a panel of genetic markers for population studies. Bioinformatic screening of the genome sequence identified micro- and mini-satellite loci, which were PCR amplified from a series of diverse parasite stocks in order to characterise their polymorphism and determine their species-specificity. A panel of 10 polymorphic markers was then selected for population genetic studies and used to genotype both cloned and uncloned isolates maintained as cell lines of T. annulata isolated from different countries. Uncloned isolates comprised a multiplicity of genotypes, while cloned isolates showed evidence of a single haploid genome. Population genetic analysis revealed a high level of genotypic diversity both between and within countries, as measured by the number of distinct multilocus genotypes. Based on measures of genetic differentiation (F<sub>ST</sub> and Nei's genetic distance), the parasite populations are geographically sub-structured and these measurements positively correlate with geographical distance. To investigate whether genetic exchange occurs at random and the populations are panmictic, the level of linkage disequilibrium was measured using the index of association across all loci. Linkage disequilibrium was observed when isolates from all countries were treated as a single population but when the isolates from Tunisia were analysed separately, linkage equilibrium was observed.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Tait, Professor Andy and Weir, Professor Willie and Shiels, Professor Brian
Authors: Weir, W., Ben-Miled, L., Karagenc, T., Katzer, F., Darghouth, M., Shiels, B., and Tait, A.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Journal Name:Molecular and Biochemical Parasitology
ISSN (Online):1872-9428

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
261721The Role of Theileria Annulata DNA Binding Polypeptides in Modulation of Bovine Gene Expression and Host Cell ProliferationBrian ShielsWellcome Trust (WELLCOTR)058933III - PARASITOLOGY