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Persistence of tick-borne encephalitis virus IV. Virus localization after intracerebral inoculation
Abstract:
Tick-borne encephalitis (TBE) virus was isolated from the brains and spinal cords, blood, livers, lymph nodes and kidneys from Macaca rhesus monkeys showing acute and subacute fatal encephalitis. In subacute encephalitis, virus titres in the CNS were lower than in acute disease (3.0--6.2 against 3.8--8.3 log LD50/ml). TBE virus localization in chronic encephalitis was largely the same as in acute and subacute disease. In monkeys with a chronic course and stable paralysis of the upper extremity, infectious TBE virus was isolated on day 383 from subcortical ganglia and spinal cord. In lymph nodes and spleen, it could be detected only by a combination of methods (co-cultivation in association with fluorescent antibody technique and complement-fixation test, explantation of organ fragments) more sensitive than is the inoculation of mice with organ homogenates. TBE virus was detected by the same methods on day 90 in the CNS and internal organs of a monkey with chronic encephalitis in the stage of remission.
Insights
Tick-borne encephalitis (TBE) virus can persist long-term in Macaca rhesus monkeys, affecting the central nervous system and other organs. Advanced detection methods reveal TBE virus presence even during remission stages of chronic encephalitis.
Area of Science:
- Virology
- Neuroscience
- Immunology
Background:
- Tick-borne encephalitis (TBE) is a significant neurological disease caused by TBE virus.
- Understanding TBE virus persistence and distribution is crucial for managing the disease.
Purpose of the Study:
- To investigate the distribution and persistence of TBE virus in Macaca rhesus monkeys with varying courses of encephalitis.
- To compare the sensitivity of different detection methods for TBE virus in various tissues.
Main Methods:
- Isolation of TBE virus from various organs (brain, spinal cord, blood, liver, lymph nodes, kidneys) of infected monkeys.
- Quantification of virus titres in the central nervous system (CNS) during acute and subacute encephalitis.
- Application of sensitive detection methods including co-cultivation, fluorescent antibody technique, complement-fixation test, and organ fragment explantation.
Main Results:
- TBE virus was isolated from multiple organs in monkeys with acute, subacute, and chronic fatal encephalitis.
- Virus titres in the CNS were higher in acute compared to subacute encephalitis.
- In chronic cases, infectious TBE virus was isolated from the CNS up to day 383, and detected in lymph nodes and spleen using sensitive methods.
- TBE virus was detected in CNS and organs on day 90 in a monkey with chronic encephalitis in remission.
Conclusions:
- TBE virus can establish persistent infections in Macaca rhesus monkeys, with prolonged presence in the CNS and lymphoid tissues.
- Sensitive detection methods are essential for identifying TBE virus in tissues, especially during chronic or remission stages.
- The findings highlight the potential for long-term viral reservoirs and the complexity of TBE pathogenesis.