Neurovirulence in cynomolgus monkeys of enterovirus 71 isolated from a patient with hand, foot and mouth disease.

Six cynomolgus monkeys were inoculated subcutaneously with enteroviurs 71 (E71), isolated from the stools of a patient with hand, foot and mouth disease (HFMD). Clinical symptoms were observed in three of the six monkeys. One monkey showed complete paralysis of the lower extremities and two animals showed weakness in the hind limbs 4 to 7 days after inoculation. Lesions were found in the central nervous system (CNS) of all monkeys. Mild to moderate vascular lesions, perivascular cuffings, degeneration and disappearance of the neurons and meningial lymphocytic infiltration were observed in the grey and/or white matter of the spinal cord, medulla oblongata, cerebral cortex and brain stem. No virus was recovered from the CNS or liver of any of the six monkeys. However, serum neutralizing antibody titers had risen in monkeys inoculated with E71.