AKDENİZ ZİRVESİ 3. ULUSLARARASI UYGULAMALI BİLİMLER KONGRESİ, Girne, Cyprus (Kktc), 17 - 18 October 2020, pp.7-8
Tropical theileriosis caused by the tick transmitted protozoa parasite Theileria annulata is an economically important disease of cattle in many developing countries. The genetic and antigenic diversity within and between field parasite populations is an important epidemiological parameter that needs to be investigated and quantified for the development and deployment of novel control strategies. The effective role of recombination for generating genetic and antigenic diversity in natural parasite populations has been proposed. These recombined and genetically diverse parasite populations can give rise to new risk factors, such as drug resistance, reduced vaccine protection, occurrence of highly pathogenic isolates. Previous data indicated that genetic and antigenic diversity in T. annulata populations vary not only between different geographical regions but also within a single host and this polymorphism is presumed to be due to the high level of genetic exchange occurring in parasite populations. The occurrence of a sexual cycle has been confirmed in a closely related orthologue parasite, T. parva, however in T. annulata, an evidence for the occurrence of mating has came from population genetic studies and no experimental data is available yet regarding to the role of recombination after transmission of T. annulata to ticks. The completed genome sequence of T. annulata provided an opportunity to develop genetic markers for population genetic studies and also enabled the identification of new antigens. In this study, a panel of 23 micro and minisatellite markers were used to identify, characterise and analyse two different clonal and nonclonal T.annulata isolates after recombination. We have measured the frequency of recombination in T. annulata isolates for each of four chromosomes. We have also investigated effect of recombination on antigenic diversity. The analysis using polymorphic markers demonstrated the existence of genetic exchange between T. annulata isolates and this evident recombination was experimentally shown for the first time. The highest level of recombination was found to be located on the forth chromosome. However, there was no correlation between recombination rate and chromosomal length. It should be pointed out that none of the recombined populations detected in the present study showed a detectable level of antigenic diversity. This study was financially supported by TUBITAK-111O718.
Key Words: Population Genetics, Sexual Recombination, Theileria annulata