• Chlamydia psittaci;
  • Ovine abortion;
  • Subtraction hybridization;
  • Strain-specific probe;
  • Helicase


Enzootic abortion in ewes (EAE) is caused by strains of Chlamydia psittaci which have the ability to invade and colonise the placenta of sheep. In an attempt to improve diagnostic methods for the detection of EAE, subtraction hybridisation was used to isolate unique fragments of the genome of an abortifacient strain (S26/3) of C. psittaci. One S26/3 strain-specific sequence identified was shown to encode a putative helicase which is repeated throughout the EAE genome. The labelled strain-specific helicase gene fragment was used in a dot-blot hybridisation test for the detection of EAE DNA in ovine placental samples. We report the identification of C. psittaci S26/3 strain-specific sequences with potential as diagnostic probes for the detection of EAE.