Generation and epitope mapping of monoclonal antibodies targeting the avian reovirus S1133 σC protein.

Avian reovirus (ARV) causes of multisystemic, immunosuppressive infectious diseases in poultry. Among them, the σC protein, a structural component of the outer capsid encoded by the S1 genome segment, plays a crucial role in viral attachment and cellular entry. In this study, we expressed the σC protein derived from the S1133 vaccine strain was expressed in a prokaryotic system and purified it. Then, using hybridoma technology, we generated two murine monoclonal antibodies (mAbs), designated 3H and 4B and shown to specifically recognize the ARV σC protein. In order to determine the linear B-cell epitopes recognized by monoclonal antibodies 3H and 4B, we localized the epitope in the 72LDD74 region using fragment truncation and site-specific mutation techniques. Furthermore, sequence analysis across ARV genotypes showed that the 72LDD74 motif is highly conserved among genotype I strains but differs substantially in genotypes II-VI, suggesting it could serve as a genotype I-specific antigenic marker. Collectively, these results support development of genotype-targeted diagnostic assays for genotype I ARV and provide a basic tool for the interaction between ARV and the host and the pathogenesis mechanism.