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Promising results for a new vaccine for louping ill control

Work on a new vaccine for louping ill has produced encouraging results, with a prototype expected to enter commercial development soon.

Louping ill is a neurological disease caused by a virus that is transmitted by ticks. It can affect many species, including humans, but is principally a problem for sheep and red grouse. The disease is a serious economic and animal welfare issue in upland and moorland areas where ticks thrive. It is expected to increase in significance as a result of climate change leading to warmer and wetter habitats that ticks prefer.

Vaccination of sheep protects against infection with the louping ill virus and also helps to protect grouse as overall numbers of infected ticks are reduced. A previous commercially available vaccine was withdrawn from sale in 2017 due to manufacturing difficulties. Since then, hill sheep farmers and grouse estate managers have reported increased numbers of cases. The new vaccine provides some hope that this increase can be reversed in the near term.

The new vaccine was developed with funding from Scottish Government and Scottish Estate Owners, collated by the Game and Wildlife Conservation Trust and is based on a new technology that will avoid the manufacturing issues of the previous vaccine. In experimental trials, the new vaccine triggered a very strong immune response (antibodies against the virus) in the vaccinated sheep and protected them from clinical disease when challenged with the virus, most likely by preventing the virus from spreading to the brain.

The cost of bringing a new vaccine to market is very high, due to the stringent regulatory requirements that are in place to ensure safety and efficacy. Although louping ill is a significant problem for sheep farmers and grouse moors in specific areas of the UK, the overall market size is relatively small compared to other livestock vaccines and this has deterred veterinary health companies from taking on production of the vaccine. Therefore, to get around this obstacle and move towards making the vaccine available as soon as possible, the commercial development will be undertaken by Moredun, working in partnership with several other agencies and companies.

Previous vaccines for louping ill were also initially developed at Moredun and comprised a killed form of the infectious virus mixed with mineral oil to enhance the immune response. Vaccines based on this methodology were in use from the 1930’s until 2017. However, because louping ill virus can infect people, it’s production is tightly controlled to prevent staff working with the virus from contracting the disease. The measures required present logistical difficulties and add additional costs to vaccine production, which ultimately limited manufacturing capacity and led to the withdrawal of the previous vaccine. Moredun’s new prototype vaccine does not require the live virus, so avoids the issues of working with infectious virus.

Dr Beth Wells, Knowledge Exchange Specialist at Moredun reported:

“Louping ill is now a very serious issue in many upland areas of the UK. We have had many reports from farmers who have suffered up to 50% losses in replacement hogs, which is completely unsustainable. As well as a serious animal welfare issue, louping ill is also a devastating disease for the farmer to deal with, as when it hits a naïve flock that has not been exposed to the virus before, it can cause sudden and high losses. We have also had recent reports of cases in cattle, dogs, ponies and humans. We have an effective research vaccine – it is really critical that it becomes available to all who need it as soon as possible.”

For more information contact Dr David Griffiths: [email protected]

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