Identification and epitope mapping of monoclonal antibodies against p150 protein of African swine fever virus.

African swine fever (ASF) is an acute and highly contagious disease caused by the African swine fever virus (ASFV) that poses a significant threat to domestic pigs and wild boars worldwide. The ASFV pp220 polyprotein plays a critical role in maintaining the structural integrity of the viral particle. The p150 protein, a cleavage product of pp220, is the second most abundant viral particle protein after the major capsid protein p72. In this study, monoclonal antibodies (mAbs) were produced using inactivated ASFV particles as the immunogen. Seven monoclonal antibodies targeting the ASFV-p150 protein were successfully generated, all exhibiting strong reactivity with ASFV. Using phage display technology, we mapped the epitope recognized by antibody 20D5, identifying the key binding region as amino acids 975-996 (NVIYQHFNLEYGEQEATKKALI). Moreover, this epitope was recognized by ASFV-positive sera, suggesting it is a naturally occurring linear B-cell epitope. Conservation analysis showed that this epitope is highly conserved in genotype I and II ASFV endemic strains. These findings enhance the understanding of p150 antigenicity and provide a basis for developing improved ASFV diagnostic tools and future vaccines.