Information from: D. K. Lvov, Institute of Virology, USSR Acad. of Med. Sciences, Gamaleya, 16, Moscow, USSR, 5 August 1975.Antigenic group: Ungrouped.Original source: Isolated by D. K. Lvov et al. at Moscow, USSR, from pool of 47 adult Dermacentor marginatus ticks collected by hand from from sheep on 14 April 1973 at Razdansk Region, Armenian SSR, Lat. 40°33'N, Long. 44°41'E. Habitat: Pastureland. Storage: Frozen at -50°C until tested.Method of isolation in laboratory: Ticks ground in Hanks' balanced salt solution containing 10% rabbit serum. Inoculated 0.01 ml ic into 2-day-old mice on 21 June 1973.Validity of isolation: Virus reisolated. Isolate was different from those viruses existing in the laboratory.Properties of virus: Physical: Filterable through Milhipore 220 nm but not 100 nm. Chemical: RNA as determined by lack of sensitivity of virus to 5-bromo-2-deoxyuridine. Resistance to chemicals: Sensitive to 50% ether; control titer 104.0, after-treatment titer <101.0. Sensitive to 1:1,000 sodium deoxycholate; control titer 104.0, after-treatment titer <101.0. Antigenic: No hemagglutinin detected employing infected suckling mouse brain extracted with sucrose acetone and tested with goose erythrocytes at pH 5.5 through 7.0 and at temperatures of 4°C and 22°C.