Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 2, 1996
Publication Date: N/A
Technical Abstract: At present, diagnosis of gastrointestinal nematode infections of cattle requires labor intensive and time consuming differentiation of larval stages from fecal egg cultures. To this end, we have developed a simple PCR based test capable of distinguishing O. ostertagi from other common gastrointestinal nematodes of cattle. In this method, we utilize a unique tandem repeat within the first internal transcribed spacer (ITS-1) of the ribosomal DNA repeat of O. ostertagi that is absent from the genera Haemonchus, Cooperia, Oesophagostomum and Nematodirus as well as other species within the genus Ostertagia. Universal PCR primers generated to span this region among cattle nematode ITS-1 sequences amplify a 1050 bp fragment from O. ostertagi and a 620 bp from all other nematode genera tested to date. The simultaneous amplification of all nematode DNA in association with the differential in fragment size of PCR products also permits the semi-quantitation of O. ostertagi eggs from animals harboring mixed infections by the inclusion of an exogenous external standard within the PCR reaction or by computer scanning of ethidium bromide stained agarose gels. Methodology is presently being developed to quantitate the potential for O. ostertagi transmission by analyzing parasite DNA isolated from eggs.