[Chronic tick-bone encephalitis virus infection in continuous human lymphocyte lines studied by molecular hybridization].

Chronic infection with tick-borne encephalitis virus (Sophyin strain) has been established in continuous lines of human lymphocytes (of T- and B-origin). In 3 lines under study, the cultured virus at the level of the 15th passage had a titre of 7.22-8.02 lg LD50ml, the virus-specific antigen was determined in the cytoplasm of 80% of T-lymphocytes (line 1387). The method of RNA-DNA hybridization demonstrated the presence of virus-specific sequences in DNA preparations from infected cells in amounts not exceeding 1 copy of virus genome per 10-25 cells.