Using two different approaches, light was shed on the role of some of post-entry determinants in the PV tissue-host tropism. In the first approach, a chimeric virus PV1(RIPO), utilizing the cognate IRES of human rhinovirus type 2 (HRV2) was used to study the potential contribution of the IRES element toward the cell tropism. Experiments were performed to shed light on the mechanism by which this variant expresses its remarkably attenuated phenotype in poliovirus-sensitive CD155 transgenic (tg) mice. The second approach was designed to study the PV tropism in a cell line known as MDCKCD155,...