Oral administration of transgenic barley expressing a Culicoides allergen induces specific antibody response
Jonsdottir, V. Svansson, S. B. Stefansdottir, E. Mäntylä, E. Marti and S. Torsteinsdottir
This in vivo study investigated a novel immunotherapy approach to Culicoides insect bite hypersensitivity (sweet itch). Barley grain expressing hyaluronidase protein originating from Culicoides saliva was fed to four Icelandic horses (immunologically naïve to Culicoides) while three controls were fed normal barley. Horses were treated six times over a period of 20 weeks with 50–100 g of barley grain each time, up to 400 g in total. Eight months after the last treatment, horses were all ‘boosted’ with 100 g.
Blood and saliva were collected from the horses before and 2 weeks after each treatment and tested with an ELISA for IgG antibodies to two Culicoides proteins. After the transgenic barley treatment, three of four horses showed an IgG1 response and all four horses were successfully boosted, significantly different from controls. A competitive inhibition ELISA showed that after the boost, transgenic barley-treated horses’ sera inhibited binding of IgE to one of the Culicoides proteins. A further competitive inhibition ELISA showed that the two proteins are not fully cross-reactive. These results show that the transgenic barley is effective at inducing an allergen-specific response and that antibodies produced are able to partially inhibit IgE binding to allergens from Culicoides species.
Oral treatment of horses with transgenic barley expressing Culicoides proteins results in an allergen-specific response and warrants further study as an immunotherapy treatment for insect bite hypersensitivity.