Chronic, relapsing myelitis in hamsters associated with experimental measles virus infection.

Chronic, relapsing myelitis has been induced in golden Syrian hamsters by the intracerebral inoculation of measles virus when the animals were less than 1 day old. No acute illness was seen in animals that developed myelitis, and the onset of the myelitis was at 5 to 50 weeks after infection. In most animals the illness was slowly progressive, with hindquarter myoclonus being the most common clinical sign. Occasionally the disease involved episodic limb paresis with nearly total recovery of limb function between periods of paralysis. In most animals pathologic changes were confined to the spinal cord and involved mononuclear cell infiltration, marked gliosis, widespread demyelination, and necrosis. Virus could not be isolated from nervous tissue by cocultivation techniques, and virus-specific immunofluorescence could not be detected. The strain of virus used was distinctive in that it contained high levels of a naturally occurring viral variant that differs from typical measles virus in several distinctive ways.