Fig. 4. Mechanism for virus motion proposed by Sakai et al.15 (a) Influenza binds tightly to a surface with multiple HA-receptor interactions. (b) NA cleaves receptors, which decreases the number of interactions and initiates motility. (c) A loosely attached virus performs crawling and gliding motions by iterative association and dissociation of HA-receptor interactions, until it reaches a site where it can form multiple interactions and again bind tightly to the surface. Reprinted from ref. 15, with permission from Springer Nature, licensed under CC BY 4.0.