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Effect of influenza A on phagocytic cell function
M Ertürk1, R Jennings, K M Oxley
1Department of Virology, Medical School, University of Sheffield, UK.
Abstract:
The effect of various strains of influenza virus on polymorphonuclear leucocyte (PMNL) function were studied by chemiluminescence (CL) and bacterial killing assays. All virus strains induced PMNL CL and peak CL correlated with haemagglutination (HA) but not neuraminidase (NA) activity of virus pools. Heat-treatment of virus pools generally had little effect on HA activity or ability to generate a PMN CL response but almost completely destroyed NA activity. Exposure of PMNL to each of the six virus strains resulted in loss of surface-associated sialic acid and a marked depression in both zymosan-induced PMNL CL and PMNL bactericidal capacity. However, there was no correlation between the degree of PMNL functional impairment and virus NA activity and, furthermore, heat treatment of virus pools removed NA activity but generally had little effect on their ability to reduce PMNL function. NA does not appear to play a primary role in impairment of PMNL function by influenza virus.
Insights
Influenza virus strains impair polymorphonuclear leucocyte (PMNL) function, reducing bacterial killing capacity. This impairment is linked to haemagglutination activity, not neuraminidase, suggesting NA doesn't primarily cause PMNL dysfunction.
Area of Science:
- Immunology
- Virology
Background:
- Influenza viruses are significant human pathogens.
- Polymorphonuclear leucocytes (PMNLs) are critical immune cells for fighting bacterial infections.
Purpose of the Study:
- To investigate the impact of different influenza virus strains on PMNL function.
- To determine the role of viral haemagglutination (HA) and neuraminidase (NA) activities in PMNL impairment.
Main Methods:
- Chemiluminescence (CL) assays were used to measure PMNL activation.
- Bacterial killing assays assessed PMNL's capacity to eliminate pathogens.
- Viral HA and NA activities were quantified and correlated with PMNL function.
Main Results:
- All tested influenza virus strains induced PMNL CL, correlating with HA activity.
- Exposure to viruses reduced PMNL's ability to generate CL and kill bacteria.
- Viral NA activity did not correlate with the degree of PMNL functional impairment.
Conclusions:
- Influenza virus impairs PMNL function, affecting both activation and bactericidal capacity.
- Haemagglutination activity, not neuraminidase, is associated with virus-induced PMNL dysfunction.
- Neuraminidase does not appear to be the primary viral factor responsible for impairing PMNL function.