Phylogenetic analysis and geographical distribution of Theileria equi and Babesia caballi sequences from horses residing in Spain

Camino, E., Cruz-Lopez, F., de Juan, L., Dominguez, L., Shiels, B. and Coultous, R. M. (2020) Phylogenetic analysis and geographical distribution of Theileria equi and Babesia caballi sequences from horses residing in Spain. Ticks and Tick-borne Diseases, 11(6), 101521. (doi: 10.1016/j.ttbdis.2020.101521) (PMID:32993941)

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Abstract

The intraerythrocytic protozoans Theileria equi and Babesia caballi are the causative agents of equine piroplasmosis (EP), one of the most important equine tick-borne diseases due to its significant impact on global international horse trade. Although EP is known to be endemic in Spain, previous phylogenetic studies have only been conducted for limited geographical regions. Therefore, the objective of this study was to evaluate the genetic diversity and distribution of these parasite species nationwide. This was performed by amplification of the 18S small subunit (SSU) rRNA gene from 100 EP positive equine blood samples using a nested PCR protocol, and sequencing the obtained amplicons. Seventy-seven T. equi and six B. caballi isolates were successfully sequenced and phylogenetic analysis revealed that the T. equi isolates grouped into the previously described clades A (n = 21/77), D (n = 1/77) and E (n = 55/77), while B. caballi isolates were placed into clades A (n = 5/6) and B (n = 1/6). Isolates from T. equi clade D and B. caballi clade B have not previously been reported in Spain. A greater intra-clade diversity (97.3–98.3 % identity) was observed between T. equi clade E isolates compared to those within clade A (99.7–100 % identity). Additionally, a multivariable logistic regression model was used to analyse associations between the clade of T. equi infection and available epidemiological data. Horses residing in Spanish northern regions were statistically more likely to be infected with T. equi clade E (p = 0.01). We conclude that while extensive sequence variation of equine piroplasms exists in Spanish infected horses, a requirement for increased equine movement controls between Spain and EP-endemic countries should be considered.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Shiels, Professor Brian and Coultous, Dr Robert and Camino, Eliazar
Creator Roles:
Camino, E.Conceptualization, Data curation, Methodology, Resources, Investigation, Writing – original draft, Writing – review and editing
Shiels, B.Conceptualization, Funding acquisition, Investigation, Resources, Validation, Writing – review and editing
Coultous, R. M.Conceptualization, Methodology, Investigation, Resources, Supervision, Validation, Writing – original draft, Writing – review and editing
Authors: Camino, E., Cruz-Lopez, F., de Juan, L., Dominguez, L., Shiels, B., and Coultous, R. M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Ticks and Tick-borne Diseases
Publisher:Elsevier
ISSN:1877-959X
ISSN (Online):1877-9603
Published Online:29 July 2020
Copyright Holders:Copyright © 2020 Elsevier GmbH
First Published:First published in Ticks and Tick-borne Diseases 11(6):101521
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
304516Coultous HBLB PostdocBrian ShielsHorserace Betting Levy Board (HBLB)VET/EPDF/2019-1Institute of Biodiversity, Animal Health and Comparative Medicine