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Persistence of tic-borne encephalitis virus in monkeys. III. Phenotypes of the persisting virus
Abstract:
The properties of tick-borne encephalitis (TBE) virus persisting for 90-383 days after intracerebral and subcutaneous inoculation of Macaca rhesus monkeys were studied, namely (1) the type of infection produced directly in the tissues of the experimental monkeys; (2) the activating effect of co-cultivation and explantation procedures; and (3) the phenotype of the isolates by a set of markers. The virus was detected and analysed in 52 instances. Directly in monkey tissues the virus induced a productive infection rarely (5.8%) but more frequently (71.2%) an abortive infection detectable by immunofluorescence (presence of virus-specific antigen). In 23% of instances a nonproductive infection was observed in monkey tissues. Like abortive infection it could be activated by the co-cultivation of cells and explantation procedures. The latter exerted a more marked activating effect than co-cultivation. The strains isolated from monkey tissues in productive infection or activated by explanation or co-cultivation were heterogeneous in their properties. The following virus phenotypes were found: virus highly virulent for mice, cytocidal and antigenically complete; a cytocidal virus of low virulence, possessing haemagglutinin; and a cytocidal virus apathogenic for mice, devoid of haemagglutinin but synthesizing complement-fixing antigen and an antigen detectable by immunofluorescence.
Insights
Tick-borne encephalitis (TBE) virus can persist in monkeys, often causing abortive or nonproductive infections. These infections can be reactivated, revealing diverse virus properties and phenotypes.
Area of Science:
- Virology
- Immunology
- Infectious Diseases
Background:
- Tick-borne encephalitis (TBE) is a significant neurological disease.
- Understanding TBE virus persistence and behavior in hosts is crucial for disease control.
Purpose of the Study:
- To investigate the properties of TBE virus persisting in Macaca rhesus monkeys.
- To characterize infection types, activation potential, and isolate phenotypes.
Main Methods:
- Intracerebral and subcutaneous inoculation of Macaca rhesus monkeys with TBE virus.
- Detection and analysis of virus in monkey tissues over 90-383 days.
- Assessing infection types (productive, abortive, nonproductive) via immunofluorescence and antigen presence.
- Evaluating activation effects of co-cultivation and explantation.
- Phenotypic characterization of isolated virus strains using markers.
Main Results:
- TBE virus persisted in monkey tissues for up to 383 days.
- Directly in tissues, productive infection was rare (5.8%), while abortive infection (71.2%) and nonproductive infection (23%) were more common.
- Both abortive and nonproductive infections could be activated by co-cultivation and explantation, with explantation showing a stronger effect.
- Isolated virus strains exhibited heterogeneity, including highly virulent, cytocidal, and apathogenic phenotypes with varying antigen and hemagglutinin presence.
Conclusions:
- TBE virus can establish persistent, often non-productive, infections in monkeys.
- Reactivation of persistent TBE virus is possible through in vitro methods.
- The study identified diverse TBE virus phenotypes, highlighting viral adaptability and potential for varied disease manifestations.