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Chronic myopathy associated with coxsackievirus type A9. A combined electron microscopical and viral isolation study
Insights
Researchers identified coxsackievirus A-9 in the muscle tissue of a child with muscular weakness. This finding supports the presence of picornavirus-like particles as actual virions in human muscle.
Area of Science:
- Virology
- Pathology
- Electron Microscopy
Background:
- Virus-like crystalline structures in human skeletal muscles are frequently observed via electron microscopy.
- However, isolation and identification of viruses from these structures have been challenging.
- Previous observations lacked definitive viral identification, leading to speculation about their nature.
Purpose of the Study:
- To identify the causative agent of muscular weakness and physical retardation in a pediatric patient.
- To investigate the nature of virus-like particles observed in human skeletal muscle tissue.
- To confirm the presence of infectious virions within muscle biopsies.
Main Methods:
- Electron microscopy was performed on muscle tissue from an 11-year-old female patient.
- The patient exhibited muscular weakness and atrophy of respiratory muscles.
- Muscle suspension was inoculated into primary human-amnion cells to assess for cytopathic effects, followed by enterovirus typing.
Main Results:
- Electron microscopy revealed picornavirus-like particles (19-23 nm) infiltrating the patient's muscle.
- Inoculation of human-amnion cells induced an enterovirus-like cytopathic effect.
- The isolated virus was identified as coxsackievirus Type A-9 using Lim-Benyesh-Meinick typing serum.
Conclusions:
- The isolation of coxsackievirus A-9 provides direct evidence for the viral etiology of the observed muscle pathology.
- This study supports the hypothesis that electron-dense particles seen in muscle are indeed infectious virions.
- The findings contribute to understanding the role of enteroviruses in human muscle disease.
Abstract:
Virus-like crystalline structures in human skeletal muscles have been observed by many electron microspists, but no viruses have been isolated and identified in such cases. An 11-year-old girl who had had muscular weakness and physical retardation since early infancy died of pneumonia due to atrophy of diaphragmatic and intercostal muscles. Electron microscopy of these muscles revealed a heavy infiltration of picornavirus-like particles that measured 19 to 23 nm in diameter. Subsequent inoculation of primary human-amnion cells with a sonic-treated suspension of the patient's diaphragmatic muscle induced an enterovirus-like cytopathic effect. The isolate was identified with use of Lim-Benyesh--Meinick enterovirus typing serum pools as coxsackievirus Type A-9. This viral isolation supports the belief that the organized electron-dense particles in human muscle are indeed virions.