Poliovirus particle or virion. The outer protein shell or capsid is shown in translucent red. The pale purple central mass that can be glimpsed through the capsid represents the ss + RNA genome. Poliovirus is a picornavirus (small rna virus). It is responsible for poliomyelitis (infantile paralysis). Polio vaccines have helped reduce the incidence of this disease. Polio eradication efforts have been funded by Rotary International and the Bill & Melinda Gates Foundation (among others). Timeline from RI.