PROTEOLYTIC PROCESSING OF REOVIRUS IS REQUIRED FOR ADHERENCE TO INTESTINAL M-CELLS

Reovirus adheres specifically to apical membranes of mouse intestinal M cells and exploits M-cell transepithelial transport activity to ente r Peyer's patch mucosa, where replication occurs. Proteolytic conversi on of native reovirus to intermediate subviral particles (ISVPs) occur s in the intestine, but it is not known whether conversion is essentia l for interaction of virus with M cells. We tested the capacity of nat ive virions, ISVPs, and cores (that lack outer capsid proteins) to bin d to intestinal epithelial cells in vivo and found that only ISVPs adh ered to M cells. Thus, intraluminal conversion of native reovirus to I SVPs is a prerequisite for M-cell adherence, and outer capsid proteins unique to ISVPs (either sigma 1 or products of mu 1) mediate interact ion of virus with M-cell apical membranes.