Molecular diagnostic assays for the detection and control of contagious equine metritis.

Contagious equine metritis caused by Taylorella equigenitalis is a highly transmissible, acute venereal disease of horses leading to endometritis, infertility and abortion in mares. It causes severe economic losses to the equine industry. Since there is no vaccine to prevent contagious equine metritis the diagnosis and subsequent quarantine along with sanitation and antibiotic treatment of affected horses are the only options for control of this venereally transmitted disease. Culture for detection of this pathogen in specimens from horses is not satisfactory due to the long incubation requirement (4 to 6 days), low number of T. equigenitalis in specimens as well as dying of T. equigenitalis during transportation of specimens to an accredited diagnostic laboratory. Several PCR and real-time PCR assays targeting 16S ribosomal RNA gene of T. equigenitalis have been developed. However, high similarity of 16S RNA of T. equigenitalis with same gene of T. asinigenitalis and other bacteria may lead to false-positive results. The goal of this project is to develop 2 molecular diagnostic assays (TaqMan real-time PCR and isothermal helicase dependent DNA amplification [tHDA]) for detection of T. equigenitalis in clinical sample from horses. These diagnostic assays will be based on sets of primers and probes targeting genes specific to T. equigenitalis that have been developed and evaluated during our previous work. The development of sensitive and highly specific real-time PCR and tHDA assays will dramatically enhance and expedite diagnostic capability providing opportunity to process large number of samples during outbreak using technical advance regional veterinary diagnostic laboratories (TaqMan real-time PCR assay) as well as rapidly analyze a few samples from horses in a minimally equipped laboratory/office setting (tHDA assay).