treatment could modulate hMPV-induced cytokine and chemokine secretion by analysing their levels in BAL samples collected at days 1 and 4 p.i. As shown in Fig. 3(a), NMSO3 treatment significantly reduced the level of the chemokine RANTES, a potent chemoattractant of mono- nuclear cells, while increasing the amount of KC, a chemokine important for neutrophil recruitment. The pro-inflammatory cytokines interleukin (IL)-1a, IL-1b, IL- 6 and tumour necrosis factor alpha were strongly upregulated in the lungs of infected animals at day 1 p.i., and NMSO3 treatment significantly reduced all four cytokine protein levels (Fig. 3b). These cytokines were no longer detectable in the BALs of infected mice at day 4 p.i. In contrast, granulocyte colony-stimulating factor (G-CSF) and gamma interferon (IFN-c) were secreted in significant amounts at day 4 p.i., and were significantly reduced in hMPV-infected animals treated with NMSO3 (Fig. 3c). Our study demonstrates that a single administration of NMSO3, at the time of hMPV infection, is effective in http://vir.sgmjournals.org NMSO3 in hMPV infection Fig. 3. Effect of NMSO3 on cytokine and chemokine release in BAL. Cytokine and chemokine production were measured using a Bioplex array in the BAL of mock- and hMPV- infected mice, either untreated or treated with NMSO3, at days 1 (a, b) and 4 (c) p.i. Data are expressed as means±SD and are represent- ative of three different experiments. *, P,0.01 relative to hMPV-infected mice. reducing viral replication, clinical illness, pulmonary inflammation and chemokine/cytokine production. The initial in vitro study suggested that NMSO3 was most effective when present at the beginning of hMPV replication, possibly affecting viral attachment and inter- nalization (Wyde et al., 2004). For this reason, we decided to treat the mice concurrently with hMPV infection. A single dose of 50 mg NMSO3 kg21 was highly effective in preventing significant body weight loss, suggesting that antiviral treatment can have a significant impact on hMPV-induced disease, as also shown recently by the use of ribavirin in a similar model of hMPV infection (Hamelin et al., 2006), in particular when administered at the beginning of infection. NMSO3 given 24 h after infection resulted in only a marginal improvement in hMPV-induced illness, as assessed by body weight loss. This result was similar to what we have shown previously with antioxidant treatment in the context of RSV infection, which was effective if given before or at the moment of 2711