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Title: COMPARATIVE SEQUENCE ANALYSIS OF THE INTERGENIC SPACER REGION OF CYATHO- STOME

Author
item KAYE, JEREMY - UNIV GLASGOW, SCOTLAND
item LOVE, SANDY - UNIV GLASGOW, SCOTLAND
item Lichtenfels, James
item MCKEAND, JACQUELINE - UNIV GLASGOW, SCOTLAND

Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Strongyloid nematodes of the subfamily Cyathostominae cause significant morbidity in horses throughout the world and, in terms of their prevalence and pathogenic significance, are now recognized as the most important parasite of the horse. A seasonal (late winter/early spring) clinical syndrome, larval cyathostomosis, commonly occurs. This syndrome is associated with the reactivation of arrested mucosal larval stages and presents as severe diarrhoea and weight loss with a 50% case fatality rate. Cyathostome infections are complex with potential 50 parasite species being involved. Most reports, however, indicate that between five and 12 species are commonly found in individual horses. Presently, identification of the different species involves morphologica1 examination of adult stages necessitating the sacrifice of infected horses. This report describes information necessary for the development of DNA probes to be used to identify the larval and egg stages of these nematodes. Such probes will be useful for diagnosing larval cyathostomosis and for evaluating chemical and biological control agents.

Technical Abstract: The ribosomal DNA intergenic spacer was amplified by the polymerase chain reaction from 16 cyathostome species using primers derived from conserved regions within the flanking 18S and 26S rRNA genes. This generated a 1.5-2.5 kb fragment which was sequenced for five species. The areas covering the 26S and 18S rRNA genes were more than 99% similar among the five species. Furthermore, in all species there existed a highly conserved region of approximately 380 bp at the 3' end of the intergenic spacer. Subsequently, two cyathostome-specific primers were designed to amplify a smaller, more variable region of the intergenic space. Eleven further species were amplified using these primers and analysis showed that sequence similarities varied from 40% to 97% between species. The sequence information obtained in this study is being used to develop a PCR-based assay for the differentiation of preparasitic stages of cyathostome.