Development and characterization of monoclonal antibodies against the N-terminal domain of African swine fever virus structural protein, p54.

African swine fever virus (ASFV), a re-emerging DNA virus, causes a highly contagious disease for domestic pigs. It is running rife worldwide and threatening the global swine industry. Protein p54 is an attractive candidate for ASFV diagnostic and vaccine design. In this work, we designed a peptide to mimic the N-terminal domain (NTD) of ASFV p54 and pretested it with sera from ASFV-infected pigs. The peptide could be well recognized by the sera, implying that the NTD of p54 contained some potential linear B cell epitopes. Then, the conjugates of the peptide with bovine serum albumin were used as the immunogen to generate monoclonal antibodies (mAbs). A total of six mAbs specific to the NTD of ASFV p54 protein were developed. Five of them well reacted with ASFV HLJ/18 strain and recognized a same linear B cell epitope ⁵ FFQPV ⁹ . Furthermore, epitope ⁵ FFQPV ⁹ could be well recognized by ASFV-positive sera from natural infected pigs, suggesting that it was a natural linear B-cell epitope. Conservation analysis indicated that epitope ⁵ FFQPV ⁹ were highly conserved among ASFV epidemic isolates belonging to genotype I and II. Alanine-scanning mutagenesis further revealed that the residues (6F to 9V) of epitope ⁵ FFQPV ⁹ were the core binding sites for antibody recognition. This is the first research to characterize specific mAbs against NTD of p54 protein. These findings may help further understand the function of p54 protein and the improvement of ASFV diagnosis.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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