Persistence of tick-borne encephalitis virus in monkeys. V. Virus localization after subcutaneous inoculation

In 28 Macaca rhesus monkeys inoculated subcutaneously (s.c.) with different strains and mutants of tick-borne encephalitis (TBE) virus and developing asymptomatic infection, TBE virus and the virus-specific antigen were found at different intervals up to 302 days post inoculation (p.i.) in the CNS and internal organs (liver, spleen, lymph nodes, kidneys). When cyclophosphane (CP) was used as an immunosuppressor, no significant changes in virus distribution were observed with the exception of more frequent isolations at early intervals from kidneys and at late intervals from spleen. With or without CP administration virus was found in the spinal cord at 3--6 days, in the cerebellum and subcortical ganglia at 11--14 days, in the cerebral cortex at 19 days p.i. Early after inoculation the virus was more frequently isolated from the CNS than from the internal organs; later (93--302 days p.i.) the persisting virus or virus-specific antigen were predominantly found in internal organs. The set of sensitive methods used facilitated to detect the persistence of TBE virus in noninfectious form in monkeys with asymptomatic infection.