CHARACTERIZATION OF NEUROVIRULENCE, STABI LITY, AND IMMUNOGENICITY OFATTENUATED VARIANTS OF LANGAT TP-21 VIRUS

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