Evaluation of immunogenicity and protective efficacy of a novel Senecavirus A strain-based inactivated vaccine in mice

Senecavirus A (SVA) is an emerging picornavirus associated with porcine idiopathic vesicular disease (PIVD), which is clinically indistinguishable from foot-and-mouth disease and other vesicular diseases in pigs. In recent years, the wide spread of SVA has caused huge economic losses to the world's pig industry. However, there are no vaccines currently available to prevent and control the infection of SVA due to the extensive diversity of SVA isolates and high cost of the pig model for vaccine evaluation. In the present study, a novel SVA CH-HNCY-2019 strain with unique amino-acid mutations in VP1, VP3 and 3C was isolated from the central part of China. A mouse model was proposed to for evaluation of the immunogenicity and protective efficacy of the inactivated CH-HNCY-2019 vaccine. The results indicated that one dose immunization of 107TCID50 inactivated CH-HNCY-2019 vaccine in mice induced a high titer of neutralizing antibody and complete protection. After challenging with the homologous virus, no viral RNA or histopathological damages were detected in the heart, liver, spleen, lung, kidney, intestine and brain tissues of the immunized mice. However, viral RNA and different degrees of histopathological damages were observed in all corresponding tissues of the unimmunized mice. In summary, the present study proved that mouse is a candidate animal model for the primary evaluation of the immunogenicity and protection efficacy of SVA vaccines for the first time. In addition, the inactivated SVA CH-HNCY-2019 vaccine was immunogenic and could protect mice against homologous viral challenges.