Two determinants in the capsid of a persistent type 3 poliovirus exert different effects on mutant virus uncoating.

Mutant polioviruses (PV) have been previously found to be capable of establishing persistent infections in HEp-2c cells. Together, two amino acid substitutions in the viral capsid of a type 3 poliovirus (PV-3), at positions VP213 and VP1(290), are sufficient to confer the persistent phenotype to a normally lytic virus. When susceptible cells are infected, the double mutant T7L+2L(13)1N(290) undergoes unique conformational changes in the capsid, modifying its sedimentation coefficient from 160S to 147S. In the present study, we have further investigated mutant PV decapsidation and, in particular, the effect of each determinant independently. Our results indicate that the novel 147S form was also generated by a mutant carrying only the determinant 1N290. This form was not produced as a result of inherent capsid instability and it was generated only upon specific PV-host cell interactions. The second viral determinant, 2L13, also modified receptor-induced conformational changes, although differently from 1N290.