Characterization of the poliovirus 147S particle:: New insights into poliovirus uncoating

A Sabin 1 strain poliovirus (PV) mutant, S1(2Y-1l), carrying a Tyr at amino acid position VP2(142) and an Ile at position VP1(160), can establish persistent infections in HEp-2c cells. This mutant forms atypical 147S particles upon interaction at 0degreesC with either cells expressing PV receptor (PVR) CD155, or PVR-IgG2a, a chimeric molecule consisting of an extracellular moiety of PVR and the hinge and Fc portion of a mouse IgG2a. Upon interaction with PVR at 37degreesC, S1(2Y-1l), similar to the parental strain, forms both 135S A particles and 80S empty capsids. At 0degreesC, surprisingly, at a concentration equal to or greater than 5 nM, PVR-IgG2a induced both the extrusion of VP4 from the capsid of S1 (2Y-1l) and the formation of 80S particles. The same transitions were observed at 0degreesC with the parental strain Sabin 1 at 40 nM PVR-IgG2a. Thus, the formation of 80S particles and VP4 extrusion, considered as one of the steps of PV uncoating, can be temperature-independent at high PVR concentration. This implies that structural changes of the PV capsid occurred following adsorption at low temperature. (C) 2002 Elsevier Science (USA).