Abstract
Reovirus intermediate subviral particles (ISVPs) but not intact virions or cores have been shown to possess the capacity to permeabilize mouse L cells as determined by a 51Cr release assay. We used monoclonal antibodies (MAbs) directed against proteins exposed on the ISVP surface (sigma 1, mu 1, and lambda 2) to probe the role(s) of these proteins in membrane interaction and penetration. One sigma 1-specific MAb (MAb-G5) and two mu 1-specific MAbs (MAb-10H2 and MAb-8H6) inhibited reovirus-induced 51Cr release when added pre- or post-ISVP attachment to L cells. MAb-G5 inhibits 51Cr release by interfering with ISVP attachment (via sigma 1) to L-cell receptor sites. The mu 1-specific MAbs (MAb-10H2 and MAb-8H6) inhibit 51Cr release by interfering with an undefined post-L-cell-attachment event that involves bivalent binding of the mu 1-specific MAbs to an epitope located in a central region of the mu 1 protein.