The transcriptomes of the cattle parasitic nematode Ostertagia ostartagi

Abstract

Ostertagia ostertagi is a gastrointestinal parasitic nematode that affects cattle and leads to a loss of production. In this study, we present the first large-scale genomic survey of O. ostertagi by the analysis of expressed transcripts from three stages of the parasite: third-stage larvae, fourth-stage larvae and adult worms. Using an in silico approach, 2284 genes were identified from over 7000 expressed sequence tags and abundant transcripts were analyzed and characterized by their functional profile. Of the 2284 genes, 66% had similarity to other known or predicted genes while the rest were novel and potentially represent genes specific to the species and/or stages. Furthermore, a subset of the novel proteins were structurally annotated and assigned putative function based on orthologs in Caenorhabditis elegans and corresponding RNA interference phenotypes. Hence, over 70% of the genes were annotated using protein sequences, domains and pathway databases. Differentially expressed transcripts from the two larval stages and their functional profiles were also studied leading to a more detailed understanding of the parasite's life-cycle. The identified transcripts are a valuable resource for genomic studies of O. ostertagi and can facilitate the design of control strategies and vaccine programs.

Fig. 1

Distribution of clusters based on life stages of origin. Total number of clusters is 2,284, majority of clusters are represented by only one stage, though further dept of sampling will likely increase representation by multiple stages.

Fig. 2

Distribution of O. ostertagi cluster BLAST matches by database. Databases used were: Caenorhabditis spp: C. elegans, C. briggsae, C. remanei; Other nematodes, all GenBank nucleotide data from nematodes except Caenorhabditis species; Non-nematodes, NR with all nematode sequences removed.

Fig. 3

Percentage representation of Gene Ontology (GO) categories for O. ostertagi clusters: A. Biological processes; B. Cellular component; C. Molecular function.

Fig. 4

Cluster composition of stage-specific clusters: A. EST distribution in L3-specific transcripts (for better visualization the biggest cluster is excluded); B. EST distribution in L4-specific clusters.

Fig. 4

Cluster composition of stage-specific clusters: A. EST distribution in L3-specific transcripts (for better visualization the biggest cluster is excluded); B. EST distribution in L4-specific clusters.