Cutting edge: Oseltamivir decreases T cell GM1 expression and inhibits clearance of respiratory syncytial virus: Potential role of endogenous sialidase in antiviral immunity

The sialoglycosphingolipid GM1 is important for lipid rafts and immune cell-signaling. T cell activation in vitro increases GM1 expression and increases endogenous sialidase activity. GM1 expression has been hypothesized to be regulated by endogenous sialidase. We tested this hypothesis in vivo using a mouse model of respiratory syncytial virus (RSV) infection. RSV infection increased endogenous sialidase activity in lung mononuclear cells. RSV infection increased lung CD8(+) T cell surface GM1 expression. Activated CD8(+) T cells in the hings of RSV-infected mice were GM1(high). Treatment of RSV-infected mice with the sialidase/neuraminidase inhibitor oseltamivir decreased T cell surface GM1 levels. Oseltamivir treatment decreased RSV-induced weight loss and inhibited,RSV clearance. Our data indicate a novel role for an endogenous sialidase in regulating T cell GM1 expression and antiviralimmunity. Also, oseltamivir, an important anti influenza drug, inhibits the clearance of a respiratory virus that lacks a neuranzinidase gene, RSV.