Identification of a Novel Conserved Antigenic Epitope by Specific Monoclonal Antibodies Targeting the African Swine Fever Virus Capsid Protein p17

African swine fever (ASF) has widely spread around the world in the last 100 years since its discovery. The African swine fever virus (ASFV) particles are composed of more than 150 proteins, with the p17 protein encoded by the D117L gene serving as one of the major capsid proteins and playing a crucial role in the virus's morphogenesis and immune evasion. Therefore, monoclonal antibody (mAb) targeting p17 is useful for the research and detection of ASFV infection. Here, we generated two specific mAbs against p17, named 1G2 and 6G3, respectively, both of which have been successfully applied in ELISA, Western blotting and immunofluorescence assay. Moreover, we found that both 1G2 and 6G3 mAbs recognize a new epitope of 72–78 amino acids of p17 protein, which is highly conserved across different ASFV strains, including all genotype I and II strains. Based on the recognized epitope, an indirect ELISA has been established to effectively detect antibodies during ASFV infection, and it exhibits high consistency with commercial ASFV ELISA kit. In summary, the production of the specific p17 mAbs and the identification of the corresponding epitope will significantly promote the serological diagnosis of ASFV and vaccine research.