Fine mapping of conserved neutralizing epitopes within the VP2 protein of Senecavirus A using monoclonal antibodies

Senecavirus A (SVA) is an emerging swine virus with global prevalence that causes vesicular disease (VD), clinically similar to foot-and-mouth disease (FMD), posing a significant concern for the swine industry. The capsid protein VP2 is a structural protein of SVA, playing a critical role in mediating viral entry into host cells and inducing the production of neutralizing antibodies. In this study, the SVA VP2 protein was expressed using the Bac-to-Bac baculovirus expression system. Six monoclonal antibodies (mAbs) targeting SVA VP2 protein were then produced by immunizing mice with the recombinant VP2 protein, named as 1A1F6, 3D5F9, 3E2C3, 5A6F5, 5F12D10 and 7H10C3, respectively. Among these, mAbs 1A1F6 and 7H10C3 exhibited neutralizing activity against SVA in vitro with IC₅₀ values of 0.64 μg/mL and 1.21 μg/mL, respectively. Finally, a linear B-cell neutralizing epitope of ¹⁵¹SLQELN¹⁵⁶ on the SVA VP2 protein was identified by determining the reactivity of the neutralizing mAbs with the truncated VP2 protein followed by peptide scanning. Peptide mutation analysis showed that the residues Ser¹⁵¹, Leu¹⁵², Leu¹⁵⁵, and Asn¹⁵⁶ within the epitope were essential for antibody binding. Multiple sequence alignment indicated that this epitope is highly conserved across various SVA strains. These findings provide a foundation for further studies on SVA and offer valuable support for the design of SVA vaccines.