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Inhibition of nitric oxide induction from avian macrophage cell lines by influenza virus
1Department of Molecular Biology, School of Veterinary Medicine, University of Wisconsin-Madison 53706.
Abstract:
The virulent avian influenza virus A/Ty/Ont/7732/66 (H5N9) (Ty/Ont) causes a rapid destruction of lymphoid cells in infected birds. Avian macrophage cell lines, HD11 and MQ-NCSU, support productive replication of Ty/Ont and other influenza viruses. Therefore, the ability of these cell lines to produce nitric oxide (NO), a potentially cytotoxic mediator, in response to infection with Ty/Ont was examined. Although treatment with bacterial lipopolysaccharides (LPS) resulted in high NO levels, infection of macrophages with Ty/Ont resulted in NO levels lower than NO levels in untreated cells. Furthermore, Ty/Ont was able to inhibit the positive response to LPS in cultures simultaneously treated with LPS and virus. However, inactivated influenza virus did not exhibit this inhibitory effect. Different strains of influenza virus varied in their ability to inhibit NO production by the macrophages; this may be related to the level of virus replication in these cells. These data suggest that the ability of the avian macrophage to activate the NO synthesis pathway is seriously impaired by infection with virulent influenza viruses such as Ty/Ont.
Insights
Virulent avian influenza virus infection impairs avian macrophages
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Avian influenza virus (AIV) A/Ty/Ont/7732/66 (H5N9) causes lymphoid cell destruction.
- Avian macrophage cell lines (HD11, MQ-NCSU) support influenza virus replication.
Purpose of the Study:
- To investigate the impact of AIV infection on nitric oxide (NO) production in avian macrophages.
- To determine if AIV interferes with macrophage inflammatory responses.
Main Methods:
- Avian macrophage cell lines were infected with AIV Ty/Ont.
- Nitric oxide (NO) production was measured following viral infection and lipopolysaccharide (LPS) stimulation.
- Inhibition of NO production by live and inactivated AIV was assessed.
Main Results:
- AIV Ty/Ont infection significantly reduced NO production in macrophages compared to untreated cells.
- Live AIV Ty/Ont inhibited LPS-induced NO production, while inactivated virus did not.
- Different influenza virus strains exhibited varying abilities to inhibit NO production.
Conclusions:
- Virulent avian influenza virus infection severely impairs the ability of avian macrophages to produce nitric oxide (NO).
- AIV actively suppresses macrophage NO synthesis, potentially contributing to viral pathogenesis.
- This impairment of NO production may be linked to the level of viral replication within macrophages.