Abstract:

Objective     To precisely determine the antigenicity and immunogenicity on N-terminal regions of DENV NS1 and develope serodiagnosis of DENV infection using an epitope-based peptide antigen. Methods    The synthesis peptide sequences of N-terminal regions of DENV NS1 were derived from the four serotype DENV standard strains and named D-1 P1, D-2 P1, D-3 P1 and D-4 P1. ELISA was performed to analyze antibody responses to these peptides from monoclonal antibodies (MAbs) with dengue serotype specificity as well as antisera from mice immunized with the dengue virus serotypes. The specific reactivity of peptides with corresponding MAbs was further conformed by competitive inhibition experiments. The degree of conservation and variability of N-terminal regions of DENV NS1 within DENV isolates which were reported in Pubmed were analysised by Bioinformatics. Results    Six DENV-1 serotype-specific MAbs (5A48A3, 5A65A2, 5B29A1, 5B71A8, 5C29A3, and 5E68A17) showed a strong reaction with D-1 P1. Six DENV-2 serotype-specific MAbs (5D21A1, 5E19A5, 5A62A12, 5A70A4, 5E30A5 and 5E48A15) showed a strong reactionwith D-2 P1. D-1 P1 only reacted with all 3 sera from DENV-1-immunized mice. The other peptides were not different from sera from mice immunized with all four dengue virus serotypes. Alignment revealed that the conservation of 100% homology for N-terminal regions of DENV-1,2,3,4 NS1 was 98.96%, 89.09%, 83.58% and 57.81%, respectively.  Conclusions    N-terminal regions of Dengue virus-1 non-structural protein 1 contained an immunodominant serotype epitope and N-terminal regions of Dengue virus-2 non-structural protein 1 contained a serotype epitope. D-1 P1-based peptide antigen will be useful for serologic diagnosis of DENV-1 infection. These novel serotype B-cell epitopes of DENV NS1 may aid the development of new dengue vaccines and serodiagnosis assays.

Key words: Dengue virus non-structural protein 1; Epitope; Serodiagnosis of DENV infection