Characterization of monoclonal antibodies and development of sandwich ELISA detecting chicken interleukin-7

Authors: Panebra, Alfredo; KIM, WH - US Department Of Agriculture (USDA); HONG, YH - US Department Of Agriculture (USDA); Lillehoj, Hyun

Submitted to: Research in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2020
Publication Date: 3/1/2021
Publication URL: https://handle.nal.usda.gov/10113/7231341
Citation: Panebra, A., Kim, W., Hong, Y., Lillehoj, H.S. 2021. Characterization of monoclonal antibodies and development of sandwich ELISA detecting chicken interleukin-7. Research in Veterinary Science. https://doi.org/10.1016/j.psj.2020.12.037.
DOI: https://doi.org/10.1016/j.psj.2020.12.037

Interpretive Summary: Limited basic knowledge on chicken immune system and its various immune mediators is hindering the development of logical prevention strategies against poultry infectious diseases. Interleukin-7 (IL-7) is a lymphocyte-produced growth factor which is essential for the development of various subpopulations of lymphocytes. In this report, ARS scientists cloned the gene for chicken IL-7 cytokine and developed an immunoassay to identify IL-7 in normal and infected chicken samples. This immunoassay is based on a pair of mouse monoclonal antibodies that are specific against chicken IL-7 and is very sensitive to monitor circulating IL-7 levels during the coccidiosis infection in chickens. Furthermore, the mAbs detecting chicken IL-7 developed in this study could be valuable immune reagents to identify IL-7 secreting cells in blood and tissues using flow cytometry and immunohistochemistry methods. Although further work is still needed to fully understand the role of chicken IL-7 functions, these mAbs will be valuable tools for basic and applied research for cell mediated immune system of chickens.

Technical Abstract: Interleukin-7 (IL-7) is a hematopoietic growth factor required for development and maintenance of lymphocytes including T-cells, B-cells, and NK cells. Recently, chicken IL-7 (chIL-7) has been cloned and studied in viral and parasite infection models. However, no monoclonal antibodies (mAbs) that specifically capture chIL-7 have been developed so far. In this study, recombinant chIL-7 was expressed for immunization and mAbs against chIL-7 were developed and characterized to investigate their immunological properties. Five mAbs exhibiting specific binding to chIL-7 were generated and determined the applicability in Western blot, ELISA, and neutralization assay. A sandwich ELISA mAb pair that enable to quantify chIL-7 protein expression in biological samples was identified and several mAbs were found to neutralize the biological activity of chIL-7 which proliferates chicken primary thymocytes. The mAbs developed in this study will be valuable reagents for immunological study in poultry.