Presence of oligoclonal immunoglobulin G bands and lack of matrix protein antibodies in cerebrospinal fluids and sera of ferrets with measles virus encephalitis.
Young adult ferrets were immunized with measles vaccine and 5 to 6 weeks later inoculated intracerebrally with Vero cells persistently infected with cell-associated strain D.R. of measles virus isolated from a patient with subacute sclerosing panencephalitis. Of nine ferrets which survived the infection for 3 weeks or longer, five showed neurological signs. At the time of death they had widespread inflammation in their brains, and cell-associated virus was isolated from three ferrets sacrificed from 5 weeks to 7 months after inoculation. Four ferrets did not develop clinical signs, but two of these had mild inflammation in the brain 7 months and 2 1/2 years after inoculation, respectively. Cerebrospinal fluids drawn by cisternal puncture from infected ferrets at the time of sacrifice had neutralizing titers against measles virus similar to the titers found in sera, but antibody against the measles virus matrix protein was not detectable. Cerebrospinal fluid showed increased immunoglobulin G (IgG) and had distinct measles virus-specific oligoclonal IgG bands. The intensity of the bands correlated with the neutralizing titers of the fluids. These results confirm and extend earlier findings and indicate that persistent measles virus infection in ferrets is similar to human subacute sclerosing panencephalitis and can be used to study certain aspects of persistent brain infections leading to subacute encephalitis.