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Degradation of Japanese encephalitis virus by neutrophils
S Srivastava1, N Khanna, S K Saxena
1Postgraduate Department of Microbiology, King George's Medical College, Lucknow, India.
Abstract:
The ability of neutrophils to degrade the phagocytosed Japanese encephalitis (JE) virion, via triggering of the respiratory burst and generation of toxic radicals has been investigated. JEV or JEV-induced macrophage derived factor (MDF) induces increase in intracellular oxidative signals with generation of superoxide anion (O2-), via activation of cytosolic NADPH and subsequent formation of hydrogen peroxide, with maximum activity on day 7 post infection. The response was sensitive to anti-MDF antibody treatment. Further, the study revealed rapid degradation of phagocytosed JE viral protein and nucleic acid. The viral protein degradation was partially dependent on the generation of toxic oxygen species as it could be abrogated by pretreatment of the cells with staurosporine.
Insights
Neutrophils degrade Japanese encephalitis virus (JEV) by triggering a respiratory burst, generating toxic oxygen species. This process, influenced by macrophage-derived factor (MDF), effectively breaks down viral proteins and nucleic acids.
Area of Science:
- Immunology
- Virology
- Cellular Biology
Background:
- Neutrophils play a critical role in the innate immune response against viral infections.
- Japanese encephalitis virus (JEV) poses a significant public health threat in many parts of Asia.
- Understanding the mechanisms of viral clearance by immune cells is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the capacity of neutrophils to degrade the Japanese encephalitis virion.
- To elucidate the role of the respiratory burst and toxic radicals in JEV degradation.
- To explore the involvement of macrophage-derived factor (MDF) in this process.
Main Methods:
- Neutrophil activation and phagocytosis assays.
- Measurement of intracellular oxidative signals, including superoxide anion (O2-) and hydrogen peroxide generation.
- Assessment of viral protein and nucleic acid degradation.
- Inhibition studies using anti-MDF antibodies and staurosporine.
Main Results:
- JEV and JEV-induced MDF significantly increased intracellular oxidative signals in neutrophils.
- Superoxide anion and hydrogen peroxide generation peaked at 7 days post-infection.
- Degradation of phagocytosed JE viral protein and nucleic acid was observed.
- Viral protein degradation was partially dependent on reactive oxygen species and was abrogated by staurosporine.
Conclusions:
- Neutrophils effectively degrade Japanese encephalitis virions through a process involving the respiratory burst and generation of toxic oxygen species.
- Macrophage-derived factor (MDF) plays a role in enhancing this neutrophil-mediated antiviral response.
- The findings highlight a key mechanism of JEV clearance by innate immune cells.