Related Experiment Videos
Infection of cultured human muscle cells by influenza virus
Abstract:
In a search for myotropic viruses with a potential to initiate muscle autoimmunity, we found that two strains of influenza A virus, A/England/863/78 (H3N2) and the reassortant virus X-47 (H3N2), could infect human syncytial myotubes lytically. The X-47 strain could, in addition, infect unicellular precursor myoblasts. Intracellular viral protein synthesis was demonstrated by pulse-labelling studies in both cell types with both virus strains. By immunofluorescence and immunoelectron microscopy, viral antigens were demonstrated in infected muscle cells specifically identified by double staining with monoclonal antibodies to either of two independent muscle-specific antigens. However, using 'co-capping' techniques in conjunction with electron microscopy, there was no evidence of association between viral haemagglutinin and the acetylcholine receptor (one major target of autoimmunity to muscle cells) on the infected cell membrane.
Insights
Two influenza A virus strains infect human muscle cells, causing cell death. Researchers found no evidence linking viral hemagglutinin to acetylcholine receptors, a key target in muscle autoimmunity.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Muscle autoimmunity, such as myasthenia gravis, involves immune responses targeting muscle cells.
- Identifying viral triggers for autoimmune diseases is crucial for understanding pathogenesis.
Purpose of the Study:
- To investigate the myotropic potential of influenza A virus strains.
- To determine if influenza A virus infection can initiate muscle autoimmunity by targeting key muscle components.
Main Methods:
- Infection of human syncytial myotubes and myoblasts with influenza A virus strains (A/England/863/78 and X-47).
- Pulse-labeling studies to detect intracellular viral protein synthesis.
- Immunofluorescence and immunoelectron microscopy to identify viral antigens in infected muscle cells.
- Co-capping assays combined with electron microscopy to assess viral hemagglutinin association with acetylcholine receptors.
Main Results:
- Both influenza A virus strains demonstrated lytic infection of human syncytial myotubes.
- The X-47 strain additionally infected unicellular precursor myoblasts.
- Intracellular viral protein synthesis was confirmed in infected muscle cells.
- Viral antigens were localized in infected muscle cells, but no association was found between viral hemagglutinin and acetylcholine receptors.
Conclusions:
- Influenza A virus strains can infect and lyse human muscle cells, including precursor myoblasts.
- Despite infecting muscle cells, the studied influenza A virus strains do not appear to directly target acetylcholine receptors, suggesting a complex mechanism for any potential role in muscle autoimmunity.