Identification of a novel conserved B-cell epitope in p15 of the African swine fever virus

African Swine Fever Virus (ASFV), a highly contagious DNA virus, causes severe economic losses to the global swine industry. The ASFV p15 protein, which is found in the core shell, is essential to the assembly of viral particles. In addition, protein p15 is a candidate target for the development of diagnostic reagents for African Swine Fever (ASF) because of its excellent immunogenicity. In this research, we prepared the p15 protein using eukaryotic expression system and validated it with sera from ASFV-infected pigs. The p15 protein could be well identified by the sera from ASFV-infected pigs, suggesting that some linear epitopes are located in the p15 protein. Furthermore, we successfully prepared two lgG1 subclass monoclonal antibodies (1E6-A7 and 3D6- D4-) specific against p15 using hybridoma technology. Using the peptide scanning method, we discovered the two mAbs well recognized the same linear epitope23LEIINNLCML32. The23LEIINNLCML32 epitope in the ASFV p15 N-terminus was identified and characterized for the first time, and it reacted well with the ASFV-positive serum, implying that it was a natural B cell linear epitope. These findings may help in the development of novel serologic diagnosis tools and the improvement of antiviral drug designs for ASF.