Regulation of plaque size and host range. Interacts with A33; this interaction is required for efficient targeting of A33 and B5 into enveloped virions. Interacts with A34; this interaction is required for the correct glycosylation, trafficking and stability of A34 and B5 incorporation into extracellular enveloped virions. Interacts with envelope phospholipase F13. B5 is found on enveloped virion (EV) membranes. The large-plaque-forming LC16m0 strain can actively proliferate in vero (YTV) cells. Belongs to the receptors of complement activation (RCA) family.