[Demonstration of the tick-borne encephalitis virus by an immunoenzyme method during a study of its persistence and the chronicity of the process in experimental animals].

The studies carried out by the authors indicated the advantages of the enzyme-immunoassay (EIA) for the detection of the persisting tick-borne encephalitis (TBE) virus and in verification of the chronic course of TBE as compared with HA test, HI test and biologic neutralization test. This method detected TBE virus in the brain of most animals developing the disease within 30-300 days postinoculation. In mice developing no disease the persisting virus was detected both directly in the organs and after preliminary amplification in a sensitive biological model and by the tissue explant method. The EIA was particularly effective in the study of persistence at later intervals (100-300 days), when the hemagglutinating and infective activities of the virus declined. The method is more informative, specific and less labor-consuming.