pvsripo pvsripo pvsripo, or pvs-ripo, is the name of a modified polio virus that has recently shown promise for treating cancer. it is the focus of clinical trials being conducted at duke university. pvsripo virus classification (unranked): virus realm: riboviria kingdom: orthornavirae phylum: pisuviricota class: pisoniviricetes order: picornavirales family: picornaviridae genus: enterovirus species: enterovirus c strain: pvsripo pvs-ripo consists of a genetically modified nonpathogenic version of the oral poliovirus sabin type 1. the internal ribosome entry site (ires) on the poliovirus was replaced with the ires from human rhinovirus type 2 (hrv2), to avoid neurovirulence. once administered, the virus enters and begins replicating within cells that express cd155/necl5, which is an onco-fetal cell adhesion molecule that is common across solid tumors. a website at duke university describes many of properties of pvsripo, and historical background about using viruses to oppose cancer. according to that website, the fda approved clinical trials with pvs-ripo in brain tumor patients recently. since may 2012, five brain tumor patients have been treated. remarkably, there have been no toxic side effects with pvs-ripo whatsoever, even at the highest possible dose (10 billion infectious virus particles). the potential value of pvsripo was the focus of a 2015 story on 60 minutes. in may 2016, the us food and drug administration granted it breakthrough therapy designation for glioblastoma.