Comparative analysis of serological activity of non-structural protein (NS1) from tick-borne encephalitis virus and its analog expressed in bacterial cells.

By means of immunoaffinity chromatography and expression of the gene in Escherichia coli, non-structural glycoprotein NS1 of tick-borne encephalitis virus (TBEV) and its recombinant analog were prepared. Antisera against these proteins were obtained by hyperimmunisation of rabbits. The antisera were tested by means of complement fixation, agar diffusion, hemagglutination inhibition and virus neutralization. Although both antisera are reacted with natural antigen, the recombinant analog of NS1 did not bind antibodies against natural protein in complement fixation and immunoprecipitation. Nevertheless the NS1 analog was rather active in ELISA. Neither the natural nor the recombinant protein protected experimental animals from lethal virus infection. A contamination of natural NS1 antigen with small amounts of structural glycoprotein E may be responsible for both antibody formation and virus neutralization. This can be relevant for the design of a subunit vaccine.