title: Characterisation of full-length cDNA sequences provides insights into the Eimeria tenella transcriptome.
abstract: BACKGROUND
  Eimeria tenella is an apicomplexan parasite that causes coccidiosis in the domestic fowl. Infection with this parasite is diagnosed frequently in intensively reared poultry and its control is usually accorded a high priority, especially in chickens raised for meat. Prophylactic chemotherapy has been the primary method used for the control of coccidiosis. However, drug efficacy can be compromised by drug-resistant parasites and the lack of new drugs highlights demands for alternative control strategies including vaccination. In the long term, sustainable control of coccidiosis will most likely be achieved through integrated drug and vaccination programmes. Characterisation of the E. tenella transcriptome may provide a better understanding of the biology of the parasite and aid in the development of a more effective control for coccidiosis.
  
  
  RESULTS
  More than 15,000 partial sequences were generated from the 5' and 3' ends of clones randomly selected from an E. tenella second generation merozoite full-length cDNA library. Clustering of these sequences produced 1,529 unique transcripts (UTs). Based on the transcript assembly and subsequently primer walking, 433 full-length cDNA sequences were successfully generated. These sequences varied in length, ranging from 441 bp to 3,083 bp, with an average size of 1,647 bp. Simple sequence repeat (SSR) analysis identified CAG as the most abundant trinucleotide motif, while codon usage analysis revealed that the ten most infrequently used codons in E. tenella are UAU, UGU, GUA, CAU, AUA, CGA, UUA, CUA, CGU and AGU. Subsequent analysis of the E. tenella complete coding sequences identified 25 putative secretory and 60 putative surface proteins, all of which are now rational candidates for development as recombinant vaccines or drug targets in the effort to control avian coccidiosis.
  
  
  CONCLUSIONS
  This paper describes the generation and characterisation of full-length cDNA sequences from E. tenella second generation merozoites and provides new insights into the E. tenella transcriptome. The data generated will be useful for the development and validation of diagnostic and control strategies for coccidiosis and will be of value in annotation of the E. tenella genome sequence.
authors.affiliation: School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor DE, Malaysia.
authors.forename: Nadzirah
authors.initials: N
authors.lastname: Amiruddin
authors.forename: Xin-Wei
authors.initials: XW
authors.lastname: Lee
authors.forename: Damer P
authors.initials: DP
authors.lastname: Blake
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Yea-Ling
authors.initials: YL
authors.lastname: Tay
authors.forename: Lik-Sin
authors.initials: LS
authors.lastname: Lim
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Tomley
authors.forename: Junichi
authors.initials: J
authors.lastname: Watanabe
authors.forename: Chihiro
authors.initials: C
authors.lastname: Sugimoto
authors.forename: Kiew-Lian
authors.initials: KL
authors.lastname: Wan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003062:Codon; D016384:Consensus Sequence; D018076:DNA, Complementary / Q000737:chemistry*; D016786:Eimeria tenella / Q000235:genetics*; D018503:Genome, Protozoan; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D059372:Nucleotide Motifs; D016366:Open Reading Frames; D015800:Protozoan Proteins / Q000737:chemistry; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D024363:Transcription Initiation Site; D059467:Transcriptome; D020506:Untranslated Regions
chemical_list: D003062:Codon; D018076:DNA, Complementary; D015800:Protozoan Proteins; D020506:Untranslated Regions