ABSTRACT
A strain of an arbovirus named Mircha was isolated from Ixodes ricinus L. ticks (30 incompletely engorged females) collected in May, 1972 from cows pastured in a forest near the village of Mircha of the Velikobereznyansky district of the Zakarpathye region of the Ukrainian SSR. The strain was found to be pathogenic for newborn white mice and rats by the intracerebral and intraperitoneal routes and for chick embryos inoculated into the yolk sac, to replicate in chick embryo fibroblast culture producing a marked cytopathic effect to be relatively stable to ethyl ether and sodium deoxylate. On the basis of the results of serological identification (CFT) it was classified into arboviruses of the Kemerovo group, the antigenic subgroup Kemeroxo-Tribec. The factors of natural focality are described briefly, and the results of the study of virus persistence in adult white mice, rats, and guinea pigs and of its immunodepressive effect are presented.