Identification of a Conserved Linear Epitope on the p54 Protein of African Swine Fever Virus

African swine fever virus (ASFV) is a highly virulent pathogen that causes nearly 100% mortality in acute infections and poses persistent risks. Effective containment of ASFV outbreaks requires rapid and reliable diagnostic tools. The p54 protein, a key structural component of ASFV, has emerged as an important target for serological detection. Herein, the recombinant p54 protein (amino acids 53-184) was expressed in <i>Escherichia coli</i>, and three mouse monoclonal antibodies (mAbs) (IgG1/kappa subtype) were developed. Among these mAbs, the mAb 1F9 specifically recognized the B-cell epitope ⁶⁶IQFINPYQDQQ⁷⁶, which is conserved across different genotypes of ASFV, suggesting that the epitope may serve as a valuable target for serological detection of ASFV. Structural modeling analysis revealed that this epitope is surface-exposed on the p54 protein, with ⁶⁷Gln and ⁶⁸Phe identified as critical residues for 1F9 binding. Moreover, a blocking ELISA based on the mAb 1F9 was established for detecting ASFV-specific antibodies in clinical serum samples, achieving a coincidence rate exceeding 95%. These findings demonstrate that mAb 1F9, targeting a conserved and accessible region of p54, represents a valuable tool for ASFV serodiagnosis, surveillance, and outbreak management.