Nataliya Shabatura, Bylgja Hilmarsdóttir, Íris Thelma Halldórsdóttir, Gunnhildur Ásta Traustadóttir and Inga Reynisdóttir
Introduction: Insect bite hypersensitivity (IBH), an IgE-mediated allergy in horses, is caused by biting midges (Culicoides spp.). The responsible Culicoides spp. are not endemic in Iceland. However, exported Icelandic horses show a high IBH-prevalence. We developed special spiral bits to orally treat horses with transgenic barley expressing Culicoides allergen. The treatment induced an allergen-specific IgG response but was impractical. The aim is to develop a practical method to treat IBH-affected horses with transgenic barley expressing Culicoides allergen.
Methods: Healthy Icelandic horses were treated with barley mixture in stable buckets, 6 with Culo2p recombinant barley and 6 with control barley. In the initiation phase, week 0-8, fed 34 times with 7.5 g of recombinant Culo2p/horse. In the maintenance phase, week 26-30, fed 8 times with 1.75g rCulo2p/horse. Blood was collected bi-weekly and saliva two weeks post treatment. Culo2p-specific IgG and the IgE blocking capacity of the sera was analysed by ELISA.
Results: Four out of six Culo2p barley treated horses produced Culo2p-specific IgG, particularly IgG1 and IgG4/7 which peaked at week 4, declined after week 8, and increased again in the maintenance phase. The induced IgG antibodies partly blocked IgE from Culo2p-binding. Culo2p-specific IgG4/7 was present in saliva of 4/6 horses.
Conclusions: Allergen-specific IgG immune response that partly inhibits IgE binding could be induced orally in horses by feeding them with transgenic barley. This can easily be done by the horse owners, but the approach needs to be verified for desensitization of IBH-affected horses against the respective allergen.
