Identification of conformational epitopes on VP1 of Senecavirus A by monoclonal antibodies and phage display

Senecavirus A (SVA) has caused widespread outbreaks across various countries, leading to significant economic losses in the swine industry. Virus-neutralizing monoclonal antibodies (NAbs) play a crucial role in investigating host-virus interactions, facilitating vaccine development, and preventing SVA infections. In this study, eight NAbs targeting VP1 were generated, identifying seven distinct antigenic epitopes. Phage display was used to locate the epitopes of the prepared monoclonal antibodies. Using phage display technology, the epitopes recognized by these monoclonal antibodies were precisely mapped. The results showed that the epitope “SHHLGPAPHFLA” was identified by 6D26, with critical residues at H₁₆₂, G₁₆₅, P₁₆₈, and F₁₇₁. And the motif “HGAVRTGTWLAQ” was determined to bind 6D22, involving residues H₁₆₂, G₁₆₅, A₁₇₂, G₁₇₆, and W₁₈₄. Three additional epitopes--“HTAIQPVAHPIV” (recognized by 4A1), “SSQSASWPAWLA” (4A2), and “NHPGSWISALDW” (4A20) --were also characterized. For 6D25, four potential binding sites (P₁₃₂, L₂₀₁, H₂₁₁, R₂₂₃) were identified, while 4A3 interacted with R₁₆₆, L₂₀₁, S₂₀₃, T₂₀₅, H₂₁₁, W₂₁₄, and Y₂₁₈. Indirect immunofluorescence assay (IFA) confirmed that the selected conformational epitopes were effectively recognized by their respective monoclonal antibodies. These findings provide valuable insights for enriching our understanding of the B cell epitopes of SVA VP1 protein, and may contribute to SVA vaccine design, diagnostic approaches, and therapeutic strategies.