Polioviruses grow readily in cell lines of primate origin. They can be cultured on monkey kidney cell lines, human amnion, HeLa, Hep-2, MRC-5, and other cell lines. The cytopathic effects consist of cell retraction, increased refractivity, cytoplas-mic granularity, and nuclear pyknosis and are observed within 48 hours of inoculation. Eosinophilic intranuclear inclusion bodies may be demonstrated in stained preparation of the infected cell lines. Well-formed plaques develop in infected monolayers with agar overlay.
Cynomolgus and rhesus monkeys are commonly used animals. They can be experimentally infected by intracerebral or intra-spinal inoculation. Cynomolgus monkeys and chimpanzees can also be infected orally. Laboratory-maintained strains may grow in rodents and chick embryos. But fresh isolates of poliovirus cannot grow in these hosts.