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Press Release: £1.1M Funding to Develop Genetic Solutions for Maedi-Visna in Sheep

A collaborative research team has been awarded a £1.1million grant to tackle the devastating impact of Maedi-visna (MV), a chronic infectious disease affecting sheep and goats. This groundbreaking project seeks to develop genetic resistance to MV, potentially transforming sheep farming and enhancing animal welfare worldwide. The three-year award involves project partners from the Moredun Research Institute and the University of Nottingham.


David Griffiths, Moredun Research Institute, project co-lead said:

Maedi visna is a serious issue for sheep farmers. This new funding will allow us to understand how best to implement genetic selection to control the disease. The result will be healthier animals and more sustainable farming.”


Rachael Tarlinton, University of Nottingham, project co-lead said

“The project has already stimulated a lot of interest as to what can be done with genotyping of sheep. We are talking to a number of sheep breeds about how to integrate this into their breeding programmes and would be really keen to talk to any interested breed societies about participating.”


The Moredun Research Institute is attending Scotland’s biggest rural event, the Royal Highland Show, taking place this week at Ingliston near Edinburgh. Visitors to the Show will be able to hear more directly about Moredun’s critical research helping farmers to detect and vaccinate for diseases to help improve animal health and welfare on farm.


Project Overview

Maedi-visna (MV) is a chronic infectious disease of sheep and goats causing severe production losses and welfare issues in sheep worldwide. It is difficult to detect and control due to a very long latent period between infection and testing positive. Farms often do not realise their animals are affected until over 50% of the flock is infected with many animals thin and dying. In the UK, the number of affected flocks has increased sharply in the last 30 years from 1.4% in 1995 to 9.4% in 2019. At least 1.6 million animals out of the UK’s 32 million strong sheep flock are affected.

MV is caused by infection with a virus, maedi visna virus (MVV), for which there is no vaccine or treatment available. Infected animals remain lifelong carriers meaning that control options are limited to testing and cull programmes. Management practices such as housing and supplementary colostrum feeding can help to mitigate the effects of MV but may be difficult to implement. Diagnostic tests are available but often fail to detect the virus, particularly in early infection. There is therefore a critical need for viable options for protecting commercial flocks from this devastating disease.

Extensive research in multiple sheep breeds and production systems has demonstrated that variation in a sheep gene encoding a protein called TMEM154 is strongly and reproducibly associated with genetic resistance to MV in sheep. This opens the possibility of using genetic selection for resistant forms of the gene to help reduce the impact of MV. Genetic selection for disease resistance is a very attractive proposition for commercial flocks as it is low cost and has previously been used to control scrapie, which is another sheep disease with a long incubation period. Several countries are already moving forward with recommending this as a viable disease reduction strategy for MV. However, before a genetic selection programme targeting TMEM154 can be recommended, there are a number of fundamental gaps in our knowledge that must be addressed.

  1. What is the role of TMEM154 in sheep tissues?
  2. What is its role in susceptibility to maedi visna virus?
  3. How common are the resistant forms of the TMEM154 gene in UK sheep breeds?
  4. Is the effectiveness of MV resistance that is mediated by TMEM154 dependent on the genetic subtype of the virus?

This research programme seeks to answer those questions to enable us to be sure that genetic selection based on TMEM154 is a safe and effective control option for reducing the impact of MV on UK sheep farms.


Expected impact

Success in the project will provide the scientific evidence to support implementation of a genetic breeding programme to control MV. Better control of MV will have enormous economic benefits for producers and lead to improved welfare of farmed sheep. Collectively, these outcomes will benefit the sustainability of sheep farming and enhance food security in the UK and worldwide.


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