[The biological properties of production strain 205 of the tick-borne encephalitis virus. Its virulence, thermostability and resistance to the action of urea].

The characterization of such properties of tick-borne encephalitis virus strain 205 and its clones as virulence, thermal stability and sensitivity to 2.5 M urea was obtained. The following combination of the genetic markers of strain 205 was established: mNic+, mNsc+, T50+, Ur. The clones possessed pronounced virulence, but showed different heat sensitivity (T50+, T50 +/-) and resistance to the action of urea (Ur and U +/-). At the early terms of observation, the clone isolated from a large viral plaque was more antigen-active.