ROLE FOR BETA-2-MICROGLOBULIN IN ECHOVIRUS INFECTION OF RHABDOMYOSARCOMA CELLS

A monoclonal antibody (MAb) that blocks most echoviruses (EVs) from in fecting rhabdomyosarcoma (RD) cells has been isolated. By using the CE LICS cloning method (T. Ward, P. A. Pipkin, N. A. Clarkson, D. M. Ston e, P. D. Minor, and J. W. Almond, EMBO J. 13:5070-5074, 1994), the lig and for this antibody has been identified as beta 2-microglobulin (bet a 2m), the 12-kDa protein that associates with class I heavy chains to form class I HLA complexes, A commercial MAb (MAb 1350) against beta 2m was also found to block EV7 infection without affecting binding to its receptor, DAF, or replication of EV7 viral RNA inside cells, Entry of EV7 into cells was reduced by only 30% by antibody and cytochalasi n D, an inhibitor of endocytosis mediated by caveolae and clathrin-coa ted pits, but was not significantly reduced by sodium azide, The block to virus entry by cytochalasin D was additive to the block induced by antibody. We suggest that EV7 rapidly enters into a multicomponent re ceptor complex prior to entry into cells and that this initial entry e vent requires beta 2m or class I HLA for infection to proceed.