Evaluation of BVDV E2 proteins based on recombinant baculovirus expression system production as diagnostic antigens and immunogens.

Bovine viral diarrhea virus (BVDV) is a significant immunosuppressive pathogen that has a major impact on the global cattle industry. Research efforts are currently focused on the envelope glycoprotein E2 of BVDV to improve immune responses. However, the full-length E2 protein is not ideal as an immune antigen and diagnostic tool, leading to the exploration of alternative strategies. In this study, we optimized the E2 gene using IDEB and ExpOptimizer software, then expressed the E2 gene using both baculovirus and E. coli expression systems. Subsequently, we assessed the immunogenicity of the purified E2 protein in mice and its application in indirect ELISA assays. Our findings showed that the Bac-E2 protein produced by the baculovirus system induced higher levels of antibody production and splenic lymphocyte proliferation in mice compared to the E. coli system. Moreover, the indirect ELISA assay developed using Bac-E2 protein exhibited superior specificity, sensitivity, and accuracy in comparison to the E. coli -expressed E2 ELISA. Overall, our study demonstrates that the optimized E2 protein generated through a baculovirus expression system elicits robust humoral and cellular immune responses in mice, making it a promising candidate for vaccine development. Furthermore, the optimized E2 protein ELISA assay shows enhanced sensitivity and accuracy, suggesting its potential as a valuable diagnostic antigen. • In this study, We optimized the E2 gene by IDEB and ExpOptimizer software, then produced the E2 gene by baculovirus and E. coli expression systems respectively, and finally evaluated the immunogenicity of the purified E2 protein in mice and its application in indirect ELISA assays. • Compared to the E. coli expression system, the Bac-E2 protein produced by the baculovirus expression system induced higher levels of antibody production in mice and significantly higher levels of proliferation of splenic lymphocytes. In addition, the specificity, sensitivity, and accuracy of the indirect ELISA assay developed by Bac-E2 protein were significantly higher than that of the E. coli -expressing E2 ELISA. • In summary, the production of optimized E2 protein by a baculovirus expression system induces strong humoral and cellular immunity in mice and is a promising vaccine candidate. In addition, the optimized E2 protein ELISA assay has improved sensitivity and accuracy compared to previous studies, making it a promising diagnostic antigen. [ABSTRACT FROM AUTHOR]