However, in hMX1-tg mice only infection with rSiAr126-NP(R328V) yielded progeny viruses in liver, lung and spleen whereas rSiAr126(wt) was suppressed to undetectable levels in all tissues (Fig 5A), indicating an efficient MxA escape of rSiAr126-NP(R328V) also in vivo. This evidence concerns the gene MX1 and infection.