Nonproductive, cell-associated virus exists before the appearance of antiviral antibodies in experimental measles encephalitis.

The ability of measles virus to induce a cell-associated state of infection in the central nervous system (CNS) plays an important role in the pathogenesis of subacute sclerosing panencephalitis (SSPE), a fatal disease of children and young adults. The mechanism by which such an infection state is established is unknown, but several hypotheses have been proposed. One of these suggests that antiviral antibodies induce the nonproductive infection state by a process termed antigenic modulation. Results presented here demonstrate that antigenic modulation is not involved in the induction of a cell-associated CNS infection in newborn hamsters by the LEC strain of SSPE derived measles virus. This follows from the finding that nonproductive, cell-associated virus can be isolated from infected CNS tissues prior to the appearance of antiviral antibodies.