[Pathogenesis of an infection induced in Syrian hamsters by attenuated strains of viruses of the tick-borne encephalitis complex].

The results of virological and morphological study of the pathogenesis of the infection induced by viruses of the tick-borne encephalitis complex (attenuated TP-21 and E-30 strains) in Syrian hamsters with normal and suppressed immune response are presented. The data obtained indicate long-term persistence of the virus-specific antigen: sufficiently high titres of specific antibodies in the blood serum of the animals at late periods after virus inoculation, positive immunoenzyme tests for virus antigen in the meninges of the hamsters inoculated with the TP-21 strain. Features of the pathogenesis were found to be related to strain characteristics, particularly the degree of their attenuation. Chronic destructive process and reparative gliosclerosis were observed in the CNS of some animals due to Protozoa of the genus Encephalitozoon; in this connection, the necessity of differential diagnosis between cuniculosis and a process of virus genesis is emphasized.