Human poliovirus particle. Computer artwork of the capsid of the human poliovirus, with proteins represented by coloured blobs. The capsid is a protein coat that encloses the virus's RNA (ribonucleic acid) genome. The protruding green proteins are receptors, which enable the virus to recognise and bind to a host cell. Poliovirus infects children and causes poliomyelitis, a disease which in severe cases damages the nervous system, leading to paralysis or death.