THE HELA-CELL RECEPTOR FOR ENTEROVIRUS-70 IS DECAY-ACCELERATING FACTOR (CD55)

Enterovirus 70 (EV70) is a recently emerged human pathogen belonging t o the family Picornaviridae. The ability of EV70 to infect a wide vari ety of nonprimate cell lines in vitro is unique among human enteroviru ses. The importance of virus receptors as determinants of viral host r ange and tropism led us to study the host cell receptor for this unusu al picornavirus. We produced a monoclonal antibody (MAb), EVR1, which bound to the surface of HeLa cells and protected them against infectio n by EV70 but not by poliovirus or by coxsackievirus B3. This antibody also inhibited the binding of [S-35]EV70 to HeLa cells. MAb EVR1 did not bind to monkey kidney (LLC-MK(2)) cells, nor did it protect these cells against virus infection. In Western immunoassays and in immunopr ecipitations, MAb EVR1 identified a HeLa cell glycoprotein of approxim ately 75 kDa that is attached to the cell membrane by a glycosyl-phosp hatidylinositol (GPI) anchor. Decay-accelerating factor (DAF, CD55) is a 70- to 75-kDa GPI-anchored membrane protein that is involved in the regulation of complement and has also been shown to function as a rec eptor for several enteroviruses. MAb EVR1 bound to Chinese hamster ova ry (CHO) cells constitutively expressing human DAF. Anti-DAF MAbs inhi bited EV70 binding to HeLa cells and protected them against EV70 infec tion. Transient expression of human DAF in murine NIH 3T3 cells result ed in binding of labelled EV70, and stably transformed NIH 3T3 cells e xpressing DAF were able to support virus replication. These data indic ate that the HeLa cell receptor for EV70 is DAF.