title: EST sequencing of the parasitic nematode Haemonchus contortus suggests a shift in gene expression during transition to the parasitic stages.
abstract: Expressed sequence tags from the parasitic nematode Haemonchus contortus were generated in order to identify anchor loci for comparative mapping between nematode genomes and candidate targets for future control measures. In total, 370 SL1 trans-spliced cDNAs from different developmental stages representing 195 different genes were partially sequenced. From these expressed sequence tags 50% were similar to genes with a known or predicted function and 19% were similar to nematode sequences with no ascribed function. From the first, free-living L1 and L3 stages relatively many cDNAs matched to housekeeping genes, and 11% (L1) or 23% (L3) of the encoded proteins were predicted to contain signal peptides. In contrast, no function could be ascribed to most of the cDNAs from the early L5 and adult parasitic stages, but for 30% (L5) or 55% (adult) of the encoded proteins a signal sequence was predicted. This limited analysis suggests that during the transition from the free-living to parasitic stages gene expression shifts towards the synthesis of less conserved extracellular proteins. These proteins offer the best perspectives for vaccine development and the development of anthelmintic drugs. In contrast, cDNAs from the first larval stages may be most suitable for comparative mapping with the free-living nematode Caenorhabditis elegans.
authors.affiliation: Department of Molecular Recognition, Institute for Animal Science and Health (ID-Lelystad), Lelystad, The Netherlands. r.hoekstra@amc.uva.nl
authors.forename: R
authors.initials: R
authors.lastname: Hoekstra
authors.forename: A
authors.initials: A
authors.lastname: Visser
authors.forename: M
authors.initials: M
authors.lastname: Otsen
authors.forename: J
authors.initials: J
authors.lastname: Tibben
authors.forename: J A
authors.initials: JA
authors.lastname: Lenstra
authors.forename: M H
authors.initials: MH
authors.lastname: Roos
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020224:Expressed Sequence Tags; D005260:Female; D015870:Gene Expression; D017238:Genes, Helminth; D005819:Genetic Markers; D006188:Haemonchiasis / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000235:genetics* / Q000254:growth & development*; D015801:Helminth Proteins / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics; D017422:Sequence Analysis, DNA; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology
chemical_list: D018076:DNA, Complementary; D005819:Genetic Markers; D015801:Helminth Proteins; D021382:Protein Sorting Signals