title: Sequence heterogeneity in the 18S rRNA gene in Theileria equi from horses presented in Switzerland.
abstract: A reverse line blot (RLB) hybridization assay was adapted and applied for equine blood samples collected at the animal hospital of the University of Zurich to determine the presence of piroplasms in horses in Switzerland. A total of 100 equine blood samples were included in the study. The V4 hypervariable region of the 18S rRNA gene was amplified by polymerase chain reaction and analyzed using the RLB assay. Samples from seven horses hybridized to a Theileria/Babesia genus-specific and a Theileria genus-specific probe. Of these, two hybridized also to the Theileria equi-specific probe. The other five positive samples did not hybridize to any of the species-specific probes, suggesting the presence of unrecognized Theileria variants or genotypes. The 18S rRNA gene of the latter five samples were sequenced and found to be closely related to T. equi isolated from horses in Spain (AY534822) and China (KF559357) (≥98.4% identity). Four of the seven horses that tested positive had a documented travel history (France, Italy, and Spain) or lived abroad (Hungary). The present study adds new insight into the presence and sequence heterogeneity of T. equi in Switzerland. The results prompt that species-specific probes must be designed in regions of the gene unique to T. equi. Of note, none of the seven positive horses were suspected of having Theileria infection at the time of presentation to the clinic. Clinicians should be aware of the possibility of equine piroplasma infections outside of endemic areas and in horses without signs of piroplasmosis.
authors.affiliation: National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Key Laboratory of Parasite and Vector Biology, Ministry of Health, WHO Collaborating Center for Tropical Diseases, Shanghai 200025, China; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: liuqin1@chinacdc.cn.
authors.forename: Qin
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: mmeli@vetclinics.uzh.ch.
authors.forename: Marina L
authors.initials: ML
authors.lastname: Meli
authors.affiliation: National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Key Laboratory of Parasite and Vector Biology, Ministry of Health, WHO Collaborating Center for Tropical Diseases, Shanghai 200025, China. Electronic address: zhang1972003@163.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: tmeili@vetclinics.uzh.ch.
authors.forename: Theres
authors.initials: T
authors.lastname: Meili
authors.affiliation: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: mstirn@vetclinics.uzh.ch.
authors.forename: Martina
authors.initials: M
authors.lastname: Stirn
authors.affiliation: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: briond@vetclinics.uzh.ch.
authors.forename: Barbara
authors.initials: B
authors.lastname: Riond
authors.affiliation: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: bweibel@wetclinics.uzh.ch.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Weibel
authors.affiliation: Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland; Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland. Electronic address: rhofmann@vetclinics.uzh.ch.
authors.forename: Regina
authors.initials: R
authors.lastname: Hofmann-Lehmann
mesh_terms: D000818:Animals; D001483:Base Sequence; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006734:Horse Diseases / Q000175:diagnosis / Q000469:parasitology*; D006736:Horses; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D016415:Sequence Alignment; D013557:Switzerland / Q000453:epidemiology; D016794:Theileria / Q000145:classification / Q000235:genetics*; D013801:Theileriasis / Q000175:diagnosis / Q000453:epidemiology / Q000469:parasitology*
chemical_list: D012337:RNA, Ribosomal, 18S
keywords: 18S rRNA gene; Equids; Piroplasms; Reverse line blot; Switzerland; Theileria equi