This was clearly evidenced in the Nd/U373MG interaction, where the level of infection could be significantly induced with moderate doses of NAs, a treatment which paradoxically did not increase attachment (Figure 5Bvs. Figure 5D), strongly suggesting that α2,3, but mainly α2,6- and α2,8-linked sia(s), may act as pseudoreceptors for the Nd virion. The gene discussed is NDP; the disease is infection.