[Characteristics of neurovirulence, stability, and immunogenicity of attenuated variants of TP-21 Langat virus].

Clones of Langat TP-21 virus with neurovirulence for primates much lower than that of Elantsev 15-20/3 strain may be obtained by threshold dilutions method on mice. Neurovirulence for monkeys of L1-L5 clones of Langat TP-21 virus obtained at our laboratory was similar to neurovirulence of A.Sabin's type III vaccinal poliomyelitis virus. Attenuated clones of Langat virus are stable and retain protective properties in experiments with mouse protection from pathogenic viruses of tick-borne encephalitis complex.