Initiation of a Sarcocystis neurona expressed sequence tag (EST) sequencing project: A preliminary report

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To accelerate genetic and molecular characterization of Sarcocystis neurona, the primary causative agent of equine protozoal myeloencephalitis (EPM), a sequencing project has been initiated that will generate approximately 7000-8000 expressed sequence tags (ESTs) from this apicomplexan parasite. Poly(A)+ RNA was isolated from culture-derived S. neurona merozoites, and a cDNA library was constructed in a unidirectional lambda phage cloning vector. Sixty phage clones were randomly picked from the library, and the cDNA inserts were amplified from these clones using the T3 and T7 primers that flank the multi-cloning site of the lambda vector. This analysis demonstrated that 100% (60/60) of the clones selected from this library contained recombinant cDNA inserts ranging in size from 0.4 to 4.0 kilobases (kb) with an average size of 1.23 kb. Single-pass sequencing from the 5′ end of the 60 amplified cDNAs produced high-quality nucleotide sequence from 53 of the clones. Comparison of these ESTs to the current gene databases revealed significant matches for 10 of the ESTs, six of which are similar to sequences from other Apicomplexa (i.e., Toxoplasma gondii). Importantly, none of the ESTs were of obvious mammalian origin, thus indicating that the cDNAs in this library were derived primarily from parasite mRNA and not from mRNA of the bovine turbinate host cells. Collectively, these data indicate that the described cDNA library will provide an excellent substrate for generating a portion of the ESTs that are planned from S. neurona. This sequencing project will greatly hasten gene discovery for this protozoan pathogen thereby enhancing efforts towards the development of improved diagnostics, treatments, and preventatives for EPM. In addition, the S. neurona ESTs will represent a significant contribution to the extensive database of sequences from the Apicomplexa. Comparative analyses of these apicomplexan sequences will likely offer a multitude of important information about the biology and evolutionary history of this phylogenetic grouping of parasites.

Original languageEnglish
Pages (from-to)233-239
Number of pages7
JournalVeterinary Parasitology
Issue number2-4
StatePublished - Feb 26 2001

Bibliographical note

Funding Information:
The technical assistance of S. Stamper, J. McKinney, the E. Bailey lab, and the K. McDowell lab is gratefully acknowledged. Bovine viral diarrhoea virus testing of parasite cultures was kindly done by M.L. Vickers. This work is supported by a grant from the Amerman Family Foundation. Published as Kentucky Agricultural Experiment Station Article No. 00-14-76, with the approval of the Director.


  • Apicomplexa
  • Equine protozoal myeloencephalitis
  • Gene expression
  • Sequence homology

ASJC Scopus subject areas

  • Parasitology
  • General Veterinary


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