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Demonstration of vaccinia virus antigen in brains of postvaccinal encephalitis cases
Abstract:
Five lethal cases of postovaccinal encephalitis (PVE) were examined in attempts to detect the viral antigen by the fluorescent antibody techniques and to isolate the infectious vaccinia virus. Histologically, the brain tissues were characterized by meningoencephalitis, with perivascular infiltrations and inflammatous reactions mainly in leptomininx, chroid plexus and ependyma. By direct immunofluorescence staining, vaccinia virus antigen was found in the brain specimens of one case, but not in the other four cases. The existence of antigen-antibody complexes was suggested by the deposition of immunoglobulins in the brain specimens. After treatment with 3 M NaSCN solution to dissociate the immunoglobulins from the complex, the viral antigen was demonstrated in specimens of two cases. Localization of viral antigen(s) thus detected coincided with that of meningoencephalitic reactions in the histological examination. Virus isolation on chick embryo chorioallantoic membrane was negative in all cases. Participation of viral pathogenicity in the etiology of PVE is discussed.
Insights
Postovaccinal encephalitis (PVE) cases showed viral antigen in brain tissue using advanced staining techniques. This suggests vaccinia virus plays a role in the meningoencephalitis observed in these lethal post-vaccination events.
Area of Science:
- Neurology
- Virology
- Immunology
Background:
- Postovaccinal encephalitis (PVE) is a rare but severe complication following vaccination.
- Understanding the etiological agents and mechanisms of PVE is crucial for public health.
Purpose of the Study:
- To investigate the presence of vaccinia virus antigen in fatal cases of postovaccinal encephalitis.
- To correlate viral antigen detection with histological findings and disease pathology.
Main Methods:
- Histopathological examination of brain tissues from five PVE cases.
- Direct immunofluorescence staining for vaccinia virus antigen.
- Immune complex dissociation using 3 M NaSCN solution followed by antigen detection.
- Virus isolation attempts on chick embryo chorioallantoic membrane.
Main Results:
- Histology revealed meningoencephalitis with characteristic inflammatory reactions.
- Vaccinia virus antigen was detected in one case by direct immunofluorescence.
- After immune complex dissociation, viral antigen was demonstrated in two cases.
- Antigen localization correlated with areas of meningoencephalitis.
- Virus isolation attempts were unsuccessful in all cases.
Conclusions:
- Vaccinia virus antigen can be present in the brain during postovaccinal encephalitis.
- Immune complex formation may obscure direct viral antigen detection.
- Viral pathogenicity likely contributes to the etiology of PVE, despite challenges in virus isolation.