Avian reticuloendotheliosis (RE) caused by reticuloendotheliosis virus (REV) is an important tumor and immunosuppressive disease posing a serious threat to poultry development. The REV envelope protein, glycoprotein (gp)-90, not only participates in cell receptor binding and viral assembly and release but also induces neutralizing antibody production. However, the antigenic epitope structure of gp90 has not yet been systematically understood. Therefore, in this study, the gp90 envelope protein of a predominant REV strain was prepared using a prokaryotic expression system, and a hybridoma cell line stably secreting the REV gp90 monoclonal antibody was developed via cell fusion and flow cytometry. Notably, a novel linear B-cell epitope, ¹⁹⁵REESVRERL²⁰³, was identified for the first time in the gp90 of REV using peptide scanning. This epitope was located on the outer side of the gp90 midpiece and was conserved across REV strains. Overall, this study is of great significance for the systematic understanding of REV antigen structure and the development of virus detection methods.

Keywords: antigenic epitope; avian reticuloendotheliosis virus; gp90; monoclonal antibody; protein expression.