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Neutrophil chemotactic factor produced by Japanese encephalitis virus stimulated macrophages
N Khanna1, M Agnihotri, A Mathur
1Postgraduate Department of Microbiology, K. G. Medical College, Lucknow, India.
Abstract:
The mechanism of neutrophil leucocytosis in cases of Japanese encephalitis is not known. We here report that during Japanese encephalitis virus (JEV) infection in mice the splenic macrophages secrete a chemotactic factor that attracts the neutrophils. The peak activity of macrophage derived factor (MDF) was observed on day 7 following infection. The MDF acted in a dose-dependent manner. This chemoattractant was purified by low pressure liquid chromatography and gave a single band of 10 kD on silver stained polyacrylamide gel. The MDF was found to be heat resistant and sensitive to prolonged incubation with proteases.
Insights
Japanese encephalitis virus infection triggers splenic macrophages to release a chemoattractant, macrophage-derived factor (MDF), which draws neutrophils to combat the infection.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- The mechanism of neutrophil leucocytosis during Japanese encephalitis (JE) remains unclear.
- Neutrophil accumulation is a common host response to viral infections.
Purpose of the Study:
- To investigate the role of splenic macrophages in neutrophil recruitment during Japanese encephalitis virus (JEV) infection.
- To identify and characterize the factor responsible for attracting neutrophils.
Main Methods:
- Infection of mice with JEV.
- Collection and assay of conditioned media from splenic macrophages.
- Purification of the chemoattractant using low-pressure liquid chromatography (LPLC).
- Analysis of purified factor by SDS-PAGE and assessment of its stability.
Main Results:
- Splenic macrophages secrete a chemoattractant factor (MDF) during JEV infection.
- Peak MDF activity was observed on day 7 post-infection.
- MDF demonstrated dose-dependent chemoattractant activity for neutrophils.
- Purified MDF appeared as a single 10 kD band on SDS-PAGE.
- MDF was heat resistant but sensitive to proteases.
Conclusions:
- Splenic macrophages play a key role in neutrophil recruitment during JEV infection by secreting MDF.
- MDF is a heat-resistant chemoattractant protein of approximately 10 kD.
- Understanding MDF's role could offer insights into host defense mechanisms against Japanese encephalitis.