Viral capsid-membrane interactions propel non-Brownian movements of nonenveloped reoviruses during entry

Understanding how nonenveloped viruses breach host cell membranes is critical for developing strategies to block viral entry, a key step in infection. Despite extensive study, how viral capsids and host lipid membranes dynamically cooperate during membrane penetration remains poorly defined. Here, using reovirus as a model nonenveloped virus and planar model membranes, we identify previously unrecognized non-Brownian membrane motions of infectious subvirion particles (ISVPs) by single-virus tracking. We then integrate experiments with computational modeling to dissect the stepwise, processive capsid-membrane interactions encoded in these distinct dynamics. We show that ISVP motion transitions from an initial phase of directed translocation to progressively confined diffusion. This behavior is consistent with a multistep entry mechanism in which initial capsid-membrane contact triggers release of the membrane-active μ1N peptide. Together, our data and simulations support a model in which membrane-inserted μ1N may accumulate locally to create retention sites that promote further virus adsorption and progressively restrict particle mobility. By directly visualizing these motion signatures, we resolve transient and cooperative capsid-membrane interactions that are difficult to capture using conventional biochemical approaches. Together, these findings provide new insight into early membrane penetration events of nonenveloped viruses.