This research developed an antibody that inhibits equine interleukin 5 to treat horses’ allergic reactions to insect bites. The study aims to offer a potential treatment for Insect Bite Hypersensitivity (IBH), a common allergic skin condition in horses.

Background of the Study

• The study is based on the prevalent health issue among horses: Insect Bite Hypersensitivity (IBH). This skin condition is caused primarily by the bites of Culicoides spp. insects.
• The bites induce a type I/IVb allergic reaction, with a significant role played by eosinophil cells. IL-5 is identified as a critical activator and regulator of these cells in horses.
• The study endeavors to create a therapeutic antibody to target IL-5 as part of a potential treatment strategy for IBH.

Research Methodology

• The researchers used phage display from the naïve human antibody gene libraries (HAL9/10) to select potential antibodies.
• A total of 28 antibodies were selected in this way, out of which, 11 proved to inhibit in the final format as chimeric immunoglobulin G with equine constant domains.
• The inhibiting capability of the antibodies was tested using a cellular in vitro inhibition assay.
• An in vitro affinity maturation process was used to further improve the two most promising antibodies. This process improved their binding activity by a factor of 2.5 and their inhibitory effect by a factor of 2.0.

Findings and Results

• The refined antibody, named NOL226-2-D10, displayed a strong inhibitory action on IL-5 binding to its receptor, with an inhibitory concentration of 4 nM.
• Furthermore, its binding activity was found to be in the nanomolar range (EC = 8.8 nM), indicating a very high affinity for its target.
• The antibody also showed stable behavior and satisfactory producibility in the lab environment, making it a good candidate for further study.

Significance and Future Implications

• The NOL226-2-D10 antibody holds promise as a future therapeutic agent to treat IBH-related allergies in horses.
• This research represents a significant advancement in veterinary medicine, introducing a novel approach to treating a common health issue in horses.
• Further in vivo studies with this developed antibody are necessary to confirm its effectiveness and safety in a live animal model before it can be considered for therapeutic use.