Summary

Equine reproductive loss due to infectious agents impacts significantly on Australian Thoroughbred breeders. A range of bacterial agents and one particular viral agent are involved. Some of these also pose a significant occupational health risk to workers in this industry. Accurate detection of the infectious agents is important for the management of affected mares. While nucleic acid testing is considered the ‘gold-standard’, testing is normally only performed by well-equipped veterinary diagnostic laboratories with molecular capabilities. This restriction means significant delays before diagnostic results are available.
We will develop and evaluate rapid nucleic acid tests for two important causes of equine reproductive loss in Australia, Equine Herpes Virus-1 (EHV-1), a recognized cause of equine abortion, and Chlamydia psittaci, an emerging cause of reproductive loss as well as zoonotic disease of veterinarians and stud workers. These assays will utilize loop-mediated isothermal amplification (LAMP) for sensitive and rapid detection of EHV-1 and C. psittaci DNA in 30 min using only basic equipment (e.g. heating block). Upon standard validation against existing traditional laboratory-based assays, innovations in (i) sample preparation to enable direct testing of a clinical specimen without DNA extraction; (ii) reagent pre-packaging to enable one-step assay preparation; and (iii) amplicon detection, allowing visualization of positive results by eye using colorimetric change, will also be incorporated into the assays allowing them to be performed in a veterinary practice or potentially stable-side. It is envisaged that the availability of these assays will support the rapid diagnosis of these diseases and timely management of affected animals by veterinarians and breeders.

Program

Thoroughbred Horses

Research Organisation

(DPI) The Crown in right of the State of New South Wales acting through the Department of Primary Industries within Regional NSW

Objective Summary

The expected outcomes are the delivery of rapid EHV-1 and C. psittaci LAMP assays with anticipated uptake by veterinary stakeholders within the project’s duration. In doing so, this project will address the RD & E Objectives 1 & 2.
Virtually nothing is known about the epidemiology of equine chlamydiosis meaning that strategies are simply not yet available for improving breeding outcomes and foal health (Objective 1). While these studies are outside of the proposed project’s scope, the availability of rapid C. psittaci assays will be critical in supporting studies to characterize the infection course in mares and to identify C. psittaci reservoirs.
Objective 2 is primarily centered on reducing the impact of diseases on horse health (2.1) and the risk to human health (2.2). The development of rapid diagnostic assays for EHV-1 and C. psittaci will support timely management of mares and foals by reducing the lag between sample collection to diagnostic result from days to hours, improving diagnostics for affected horses (Goal 2.1.3s). By developing these assays in collaboration with clinicians and breeders, we will also directly communicate strategies for their effective use (2.1.3l). C. psittaci is a zoonotic pathogen with recent human cases linked to exposure to equine foetal membranes. There is currently no way to assess the risk in infected horses so the availability of rapid testing will support clinicians and stud workers in implementing appropriate infection control procedures more rapidly in positive cases, thereby addressing short (2.2.1s) and long (2.2.1l) term goals to describe and manage the risk