Identification of two novel T cell epitopes on the E2 protein of classical swine fever virus C-strain.

C-strain, also known as the HCLV strain, is a well-known live attenuated vaccine against classical swine fever (CSF), a devastating disease caused by classical swine fever virus (CSFV). Vaccination with C-strain induces a rapid onset of protection, which is associated with virus-specific gamma interferon (IFN-γ)-secreting CD8 ⁺ T cell responses. The E2 protein of CSFV is a major protective antigen. However, the T cell epitopes on the E2 protein remain largely unknown. In this study, eight overlapping nonapeptides of the E2 protein were predicted and synthesized to screen for potential T cell epitopes on the CSFV C-strain E2 protein. Molecular docking was performed on the candidate epitopes with the swine leukocyte antigen-1*0401. The analysis obtained two highly conserved T cell epitopes, ⁹⁰ STEEMGDDF ⁹⁸ and ³³¹ ATDRHSDYF ³³⁹ , which were further identified by enzyme-linked immunospot assay. Interestingly, the mutants deleting or substituting the epitopes are nonviable. Further analysis demonstrated that ⁹⁰ STEEMGDDF ⁹⁸ is crucial for the E2 homodimerization, while CSFV infection is significantly inhibited by the ³³¹ ATDRHSDYF ³³⁹ peptide treatment. The two novel T cell epitopes can be used to design new vaccines that are able to provide rapid-onset protection.
Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest.
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