Nitric oxide production is increased during murine vaccinia virus infection, but may not be essential for virus clearance.
Rolph MS., Ramshaw IA., Rockett KA., Ruby J., Cowden WB.
Recent reports have highlighted a potential antiviral activity for nitric oxide (NO). The purpose of this study was to investigate the production of NO in mice during vaccinia virus (VV) or herpes simplex virus type 1 infection, and to assess the role of NO in clearance of VV. Reactive nitrogen intermediates (RNI; NO and its stable oxidation products, nitrite and nitrate) were significantly elevated in the plasma of mice infected with these viruses. Furthermore, spleen cells from virus-infected mice produced elevated RNI levels following stimulation in vitro with LPS. NO production during VV infection was critically dependent on the cytokines tumor necrosis factor and interferon-gamma, and on the presence of both CD4+ and CD8+ T lymphocytes. Treatment of VV-infected mice with the nitric oxide synthase inhibitor N(G)-methyl-L-arginine did not alter the course of infection, suggesting that NO may not be essential for the clearance of this virus.