Barley produced Culicoides allergens are suitable for monitoring the immune response of horses immunized with E. coli expressed allergens.

The research focuses on the use of barley-produced Culicoides allergens for monitoring the immune response in horses. These horses have been vaccinated with allergens produced by E. coli to help the defense against allergic reactions caused by the bites of midges from the Culicoides family.

Background and Purpose of the Study

• The study was conducted in response to Insect Bite Hypersensitivity (IBH), an allergic skin condition in horses caused by beers from the Culicoides midges family.
• The implementation of effective preventive and therapeutic allergen immunotherapy (treatments that reduce sensitivity to allergens) for IBH requires an ample supply of pure, endotoxin-free allergens.
• The primary aim was to compare the immune response in horses to allergens Cul n 3 and Cul n 4 produced in transgenic barley grains versus the same allergens expressed in E. coli or insect cells.

Allergen-specific IgG Responses

• To evaluate the response, allergen-specific IgG (a type of antibody) responses were measured using ELISA in sera from twelve horses before and after being vaccinated with E. coli manufactured allergens.
• The study found that before vaccination, no IgG binding to either the barley or insect cell-produced proteins was detected. Post-vaccination, they observed a similar increase in specific IgG to both types of allergens.
• However, while IgG levels reacting to the E. coli expressed proteins were higher in the vaccinated horses, some background binding was observed before vaccination as well.
• The comparable IgG responses suggest both types of allergens were able to provoke a similar immune response.

In Vitro Re-stimulation of PBMC

• In addition to testing IgG responses, the study performed in vitro (lab environment) re-stimulation of Peripheral Blood Mononuclear Cells (PBMC) for measurements of cytokines, which are small proteins that play important roles in cell signaling during immune responses.
• Numerous issues were noted with the E. coli expressed proteins, which produced high background interference in PBMC from non-vaccinated control horses. This could potentially skew results and complicate data interpretation.
• In contrast, the barley and insect cell expressed proteins induced similar amounts of IFN-γ and IL-4, two important cytokines, in PBMC from vaccinated horses, providing cleaner, more reliable results.

Conclusion

• The study concludes that barley-produced allergens are promising tools for use in immunoassays (biochemical tests that measure the presence or concentration of a substance in solutions) due to their ability to reliably measure and monitor horse immune responses to vaccination.