Researchers from the University of Bristol have succeeded in isolating proteins inmidge saliva that could cause the allergic condition sweet itch.

It is hoped that one or more of these proteins could be used in an immunotherapy programme to reduce the allergic reaction in sweet itch sufferers.

Sweet itch, which is usually caused by an allergic reaction midge bites, affects thousands of horses, ponies and donkeys in the UK and worldwide causing extreme discomfort with horses experiencing a range of symptoms including severe itching, hair loss, rashes and weeping sores.

Researchers have isolated over 20 potential allergens in the saliva of midges There is no cure for sweet itch, but research that was given £141,410 funding by The Horse Trust offers a potential ray of hope for owners of horses affected with Sweet Itch.

The research, which is being carried out at the University of Bristol School of Veterinary Science, has isolated over 20 potential allergens in the saliva of midges and has identified many of the genes that make these proteins. As there are numerous species of midge that bite horses, the researchers have concentrated on identifying the main salivary proteins in three different groups of midges including representatives of the types that are known to commonly bite horses in the UK.

The work is now starting to manufacture these proteins using recombinant DNA techniques: the midge DNA is inserted into an insect virus (known as a bacculovirus), insect cells are infected with this modified virus and then produce the protein coded by the midge DNA.

The researchers said “We are now halfway there – we know what proteins are in midge saliva and how to manufacture them in sufficient quantities. The next step is finding out which of these proteins allergic horses respond to and then by giving them regular doses of this protein to reduce their immune reaction. We hope this can be achieved by feeding the midge proteins to the horse so that its immune system responds to them as it would to a normal food and turns off the allergic response.”

The Horse Trust is keen to fund the next stage of this research, but a reduction in income from individual donors during the credit crunch has forced the charity to suspend its grant programme, although it is continuing to fund research and educational grants made in earlier years using its reserves.

To donate to the charity, or for more information on the Sweet Itch research, visit or call 01494 488 464.

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