PVSRIPO, a variant of the poliovirus, is a revolutionary virus that demonstrates key characteristics for oncolytic virotherapy due to its ability to attack glioblastomas. The first criteria that PVSRIPO demonstrates is tumor-targeting tropism. PVSRIPO binds to nectin-like molecule 5 (Necl-5), a poliovirus receptor (PVR), found on different types of cancers such as lung cancer, colorectal cancer, and glioblastomas. This allows the virus to have a high binding affinity to tumor cells. Secondly, after modifying the poliovirus by substituting its internal ribosome entry site (IRES) with the Human Rhinovirus 2's (HRV2) IRES, the poliovirus becomes PVSRIPO, an attenuated version of the virus that will not negatively affect normal cells. Lastly, the most notable effect of PVSRIPO is evoking a host immune response against tumor cells by activating natural killer cells, macrophages and dendritic cells which help the immune system fight tumors.