Identification of a novel antigenic epitope in envelope protein of avian reticuloendotheliosis virus

Reticuloendotheliosis is a devastating poultry disease causing tumors and immunosuppression in infected birds. Caused by reticuloendotheliosis virus, it carries a surface glycoprotein (gp90) that mediates viral infection, assembly, release and induces protective antibodies, yet the specific gp90 regions triggering immune responses remain poorly understood. In this study, we expressed gp90 of a prevalent REV strain via a prokaryotic system and established a hybridoma cell line stably secreting gp90-specific monoclonal antibodies through cell fusion and flow cytometric screening. Most notably, we identified a novel linear B-cell epitope, 195REESVRERL203, on gp90 for the first time. Localized to the outer mid-domain of gp90 and conserved across REV strains, this epitope defines a key immunogenic structure, offering insights for targeted diagnostics and control strategies against this economically impactful disease.