Potocnakova L, Bhide M, Pulzova LB. showed that the peptide-specific guinea pig antisera of IDE2 could neutralize SVA strain CH/FJ/2017, and IDE2 was identified as a novel potential neutralizing linear epitope. This is the first time VP2 IDEs have been identified by using the Pepscan method and a bioinformatics-based computational prediction method. These results will help elucidate the antigenic epitopes of VP2 and clarify the basis for immune responses against SVA. IMPORTANCE The clinical symptoms and lesions caused by ddATP SVA are indistinguishable from those of other vesicular diseases in pigs. SVA has been associated with recent outbreaks of vesicular disease and epidemic transient neonatal losses in several swine-producing countries. Due to the continuing spread of SVA and the lack of commercial vaccines, the development of improved control strategies is urgently needed. ddATP The VP2 protein is a crucial antigen on the capsids of SVA particles. Furthermore, the latest research showed that VP2 could be a promising candidate for the development of novel vaccines and diagnostic tools. Hence, a detailed exploration of epitopes in the VP2 protein is necessary. In this study, four novel B-cell IDEs were identified using two different antisera with two different methods. IDE2 was identified as a new neutralizing linear epitope. Our findings will help in the rational design of epitope vaccines and further understanding of the antigenic structure of VP2. KEYWORDS: senecavirus A, SVA, VP2 protein, immunodominant epitope, Pepscan INTRODUCTION Senecavirus A (SVA) is a type of nonenveloped single-stranded, positive-sense RNA virus belonging to the family infection (19). Therefore, the neutralization of ddATP SVA might be mediated through antigenic epitopes located mainly on the surface of the external viral capsid proteins (VP1, VP2, and VP3). These proteins may represent potential candidates for the development of novel vaccine formulations. Previous data indicated that VP2 plays a major role in early IgM-mediated neutralization and IgG-mediated neutralization. Moreover, the IgG titer of VP2 is approximately twice that of VP3, and antibodies to VP2 last longer than those to VP1 and VP3 (19). Therefore, the VP2 protein could be a promising candidate target for the development of novel epitope-based vaccines and suitable epitope-based diagnostic tools for SVA. Antigenic complexes could include protective B-cell and T-cell epitopes and exclude potentially immunosuppressive and immunopathogenic determinants (20,C23). Epitope-based vaccines containing selected immunogenic targets may represent an alternative and novel strategy to combat SVA (24, 25). Considering the importance of the VP2 protein in adaptive immune responses in pigs infected with SVA, a detailed exploration of epitopes in the VP2 protein is necessary (19). In this study, we defined four linear immunodominant epitopes (IDEs) of the VP2 protein in SVA strain CH/FJ/2017 using Pepscan and bioinformatic prediction methods and further analyzed their antigenicity and immunogenicity. A neutralization test indicated that IDE2 (amino acids [aa] 145 to 160) could induce a neutralizing antibody response against SVA. The results will help in the rational design of epitope vaccines by furthering the understanding of the antigenic structure of VP2 and will contribute to the development of diagnostic tools for the specific serological diagnosis of SVA infection. RESULTS Structure and quality assessment of the VP2 protein BL21(DE3). Purified recombinant VP2 protein was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the MW of the VP2 Rabbit Polyclonal to SNIP protein was approximately 36?kDa (Fig.?2A). Western blot analysis was performed using SVA-positive pig sera and anti-His monoclonal antibody (MAb). The results showed that the VP2 protein was detected, and the size was as expected (Fig.?2B). The results demonstrated that we obtained high-purity recombinant VP2 protein that could be used to prepare polyclonal antibodies by immunizing rabbits. Open in a separate window FIG?2 Characterization of recombinant VP2 protein and its immune serum. (A) SDS-PAGE analysis of purified recombinant VP2 protein. (B) Western blot analysis of purified recombinant VP2 protein with anti-His MAb (lane 1) and with SVA antiserum (lane 2). (C) Induced antibody levels against VP2 protein were detected by iELISA. (D).