Recombinant protein NS1 of highly-virulent strain Sofjin in bacterial expression system E.coli B834 – pET22b are obtained. Optimization methods of purification and refolding are performed. Recombinant protein structure was confirmed by MS identification of tryptic peptide mapping. Using ELISA and dot-blot analysis with monoclonal antibodies immunochemical activity of recombinant protein are shown. NS1 protein-based advantage of early diagnostics tick-borne encephalitis virus infection and perspectives use in vaccine development are discussed.