[Multiple forms of the NS1 protein as the main component of the nonvirion ("soluble") antigen of the tick-borne encephalitis virus].

The nonstructural virus-specific NS1 protein of tick-borne encephalitis (TBE) virus was found to be the main antigenic component of the nonvirion ("soluble") antigen which had been shown previously to present a complex protein structure closely associated with the infected cell membranes. In the presence of sodium dodecylsulphate, beta-mercaptoethanol and 8M urea NS1 protein could be detected in the form of oligomeric molecules which disintegrated to monomers after heating at 100 degrees C for 5 min. The infected cell membrane-associated NS1 protein was shown to differ in electrophoretic mobility from the NS1 protein released into the culture fluid in the course of virus infection. The conditions for detection of NS1 protein and its oligomeric forms by PAG electrophoresis and immune blotting were determined. Dimeric forms of NS1 protein were found to contain products of its proteolysis. NS5 protein was found together with NS1 protein in TBE nonvirion antigen and also possessed antigenic activity.