OPA virus detection in sheep

OPA - Jaagsiekte Sheep Retrovirus (JSRV) Project

Pilot study to assess the performance of PCR to detect Jaagsiekte Sheep Retrovirus (JSRV) infected sheep as part of a “thin ewe” diagnostic package


Ovine Pulmonary Adenocarcinoma (OPA) is an infectious lung cancer specific to sheep. It is caused by Jaagsiekte Sheep Retrovirus (JSRV); there is no treatment or vaccine and once symptoms develop it is fatal. Affected flocks can expect to lose up to 20% of their stock in the first 2 years. OPA is of continuing concern to the UK sheep industry. Reliable and accurate diagnosis of pre-clinical signs of OPA is currently unavailable and the requirement for a test is increasing.

Previously a PCR (Polymerase Chain Reaction) test that detects JSRV-infected cells in sheep blood was developed but with comparatively low sensitivity with respect to individual animals. By applying the test to a number of sheep in a flock the blood PCR can be used as a flock test, however the specificity and sensitivity has not been proven.


The aim of the project is to assess whether the JSRV PCR test, when used on a subset of animals that are exhibiting poor body condition, one of the clinical signs that may represent early OPA, is an effective flock test for OPA. The study also aims to determine whether samples of peripheral blood or of nasal secretions perform best.  The project will refine the PCR test currently used in a research setting, for transfer to a commercial laboratory.

Why is it important?

OPA is a continuing concern to the UK sheep industry. Feedback from Moredun Research Insititute (MRI) events such as Scotsheep, Northsheep, Royal Highland and Royal Welsh shows have highlighted the need for information about OPA and the development of interventions to control the disease. Addressing this need will then help improve health and welfare through health planning, better biosecurity and improved understanding of animal disease and its control.

Who will carry out the project?

The research will be lead by the MRI. The project will be funded by HCC, AHDB Beef and Lamb, BioBest Laboratories and Animal and Plant Health Agency (APHA).

Project timeframe

Start: October 2015

Duration: 12 months

Finish: September 2016