MONOCLONAL-ANTIBODIES TO REOVIRUS SIGMA-1 AND MU-1 PROTEINS INHIBIT CHROMIUM RELEASE FROM MOUSE L-CELLS

Reovirus intermediate subviral particles (ISVPs) but not intact virion s or cores have been shown to possess the capacity to permeabilize mou se L cells as determined by a Cr-51 release assay. We used monoclonal antibodies (MAbs) directed against proteins exposed on the ISVP surfac e (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 (MA b-G5) and two mu 1-specific MAbs (MAb-10H2 and MAb-8H6) inhibited reov irus-induced Cr-51 release when added pre- or post-ISVP attachment to L cells. MAb-G5 inhibits Cr-51 release by interfering with ISVP attach ment (via sigma 1) to L-cell receptor sites. The pi-specific MAbs (MAb -10H2 and MAb-8H6) inhibit Cr-51 release by interfering with an undefi ned 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 m u 1 protein.