Discovery of a novel species, Theileria haneyi n. sp., infective to equids, highlights exceptional genomic diversity within the genus Theileria: implications for apicomplexan parasite surveillance
Name:
Publisher version
View Source
Access full-text PDFOpen Access
View Source
Check access options
Check access options
Date
2018Journal
International Journal for ParasitologyPublisher
Elsevier LtdType
Article
Metadata
Show full item recordAbstract
A novel apicomplexan parasite was serendipitously discovered in horses at the United States - Mexico border. Phylogenetic analysis based on 18S rDNA showed the erythrocyte-infective parasite to be related to, but distinct from, Theileria spp. in Africa, the most similar taxa being Theileria spp. from waterbuck and mountain zebra. The degree of sequence variability observed at the 18S rDNA locus also suggests the likely existence of additional cryptic species. Among described species, the genome of this novel equid Theileria parasite is most similar to that of Theileria equi, also a pathogen of horses. The estimated divergence time between the new Theileria sp. and T. equi, based on genomic sequence data, is greater than 33 million years. Average protein sequence divergence between them, at 23%, is greater than that of Theileria parva and Theileria annulata proteins, which is 18%. The latter two represent highly virulent Theileria spp. of domestic cattle, as well as of African and Asian wild buffalo, respectively, which differ markedly in pathology, host cell tropism, tick vector and geographical distribution. The extent of genome-wide sequence divergence, as well as significant morphological differences, relative to T. equi justify the classification of Theileria sp. as a new taxon. Despite the overall genomic divergence, the nine member equi merozoite antigen (EMA) superfamily, previously found as a multigene family only in T. equi, is also present in the novel parasite. Practically, significant sequence divergence in antigenic loci resulted in this undescribed Theileria sp. not being detectable using currently available diagnostic tests. Discovery of this novel species infective to equids highlights exceptional diversity within the genus Theileria, a finding with serious implications for apicomplexan parasite surveillance. Copyright 2018Sponsors
This work was supported by the Agricultural Research Service ( ARS ), USA, CRIS#2090-320000-034-00D and in part by the Washington State University College of Veterinary Medicine Equine Infectious Diseases Research Program. Appendix AKeyword
18S rDNAEqui merozoite antigen superfamily
Equids
Phylogenetic analysis
Protein sequence divergence
Theileria
Identifier to cite or link to this item
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048341084&doi=10.1016%2fj.ijpara.2018.03.010&partnerID=40&md5=9ce14ede12adbc2f003f6b29bdd88626; http://hdl.handle.net/10713/9722ae974a485f413a2113503eed53cd6c53
10.1016/j.ijpara.2018.03.010
Scopus Count
Collections
Related articles
- Molecular genotyping and epidemiology of equine piroplasmids in South Africa.
- Authors: Bhoora RV, Collins NE, Schnittger L, Troskie C, Marumo R, Labuschagne K, Smith RM, Dalton DL, Mbizeni S
- Issue date: 2020 Mar
- Sequence heterogeneity in the equi merozoite antigen gene (ema-1) of Theileria equi and development of an ema-1-specific TaqMan MGB assay for the detection of T. equi.
- Authors: Bhoora R, Quan M, Matjila PT, Zweygarth E, Guthrie AJ, Collins NE
- Issue date: 2010 Aug 27
- Genetic characterization of Theileria equi infecting horses in North America: evidence for a limited source of U.S. introductions.
- Authors: Hall CM, Busch JD, Scoles GA, Palma-Cagle KA, Ueti MW, Kappmeyer LS, Wagner DM
- Issue date: 2013 Feb 11
- Genetic diversity of Theileria equi and Babesia caballi infecting horses of Central-Southern Italy and preliminary results of its correlation with clinical and serological status.
- Authors: Manna G, Cersini A, Nardini R, Bartolomé Del Pino LE, Antognetti V, Zini M, Conti R, Lorenzetti R, Veneziano V, Autorino GL, Scicluna MT
- Issue date: 2018 Jul
- Comparative genomic analysis and phylogenetic position of Theileria equi.
- Authors: Kappmeyer LS, Thiagarajan M, Herndon DR, Ramsay JD, Caler E, Djikeng A, Gillespie JJ, Lau AO, Roalson EH, Silva JC, Silva MG, Suarez CE, Ueti MW, Nene VM, Mealey RH, Knowles DP, Brayton KA
- Issue date: 2012 Nov 9