Prevalence and phylogenetic analysis of Theileria equi in Iranian dromedaries

Document Type: Original Articles

Authors

1 Department of Parasitology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

2 Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

3 Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran

Abstract

Considering the importance of Theileria equi infection in horse breeding industry and marketing, in the present study, we aimed to determine the prevalence of T. equi among dromedaries in central Iran, where a considerable number of camels and horses are raised and equine theileriosis is quite prevalent. For this purpose, a total of 161 blood samples from camels were examined in terms of T. equi infection, using parasitological and molecular methods. For molecular detection of T. equi, primers targeting the 18S rRNA gene were selected. Microscopic examination revealed that 0.6% of camels were positive for the intraerythrocytic stage of Theileria species, while polymerase chain reaction (PCR) method detected T. equi in 7 (4.3%) out of 161 camels. Sequences of 18S rRNAs from all the isolates showed more than 99% homology to each other and T. equi isolates in the GenBank. With respect to the single-nucleotide substitution in 18S rRNA gene of the studied camels, three different genotypes were identified and submitted to the GenBank. Considering the homology between 18S rRNA sequences of T. equi in the studied samples and those available in the GenBank, the phylogenetic tree formed three distinct, but highly-related clusters. In this study, age, gender, and locality were not determined as risk factors for T. equi infection in camels. In conclusion, this study demonstrated that T. equi is present among Iranian camels.

Keywords

Main Subjects


Article Title [French]

Prévalence et analyse phylogénétique de Theileria equi infectant les dromadaires iraniens

Abstract [French]

Etant donnée l’importance des infections causées par Theileria equi dans l’industrie et le marché des chevaux d’élevages, l’objectif de cette étude était de déterminer la prévalence de T. equi chez les dromadaires du centre de l’Iran. Cette région, où les élevages de camélidés et de chevaux sont abondants, est aujourd’hui particulièrement touchée par la theilériose équine. Dans cette étude, la présence d’infection au T. equi a été examinée sur un total de 161 prélèvements sanguins de dromadaires un utilisant des méthodes de parasitologie et moléculaires. Pour la détection moléculaire de T. equi, des amorces visant la séquence du gène 18S de l’ARNr ont été sélectionnées. Alors que nos observations microscopiques indiquaient une contamination au Theileria spp. en phase intraérythrocytaire pour 0.6% des dromadaires, nos analyses moléculaires par PCR nous ont permis de détecter 7 cas (4,3%) d’infection à T. equi sur les 161 échantillons testés. Les séquences du gène 18S de l’ARNr de tous les isolats détectés et celles des isolats de T. equi répertoriées dans GenBank étaient homologues à plus de 99%. Trois génotypes différents ont été identifiés et annotés dans GenBank selon leurs substituions nucléotidiques uniques sur la séquence 18S de l’ARNr. Etant donnée la forte homologie entre les séquences 18S de l’ARNr des isolats de T. equi identifiés dans nos échantillons et celles disponibles dans GenBank, ces génotypes constituent trois groupes distincts, mais étroitement liés dans l’arbre phylogénétique. De plus, cette étude montre que l’âge, le sexe et la localité des dromadaires n’influent pas sur le risque d’infection au T. equi. En conclusion, nos analyses ont révélé la présence d’infections au T. equi chez les dromadaires iraniens.

Keywords [French]

  • Theileria equi
  • dromadaire
  • Réaction en chaîne de la polymérase
  • Analyse phylogénétique
  • Yazd

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