Subacute sclerosing panencephalitis: are antigenic changes involved in measles virus persistence?

Subacute sclerosing panencephalitis (SSPE) is a rare, fatal complication of measles virus infection arising years after acute measles. During this chronic disease process, characteristic measles virus inclusions are present in the cells of the central nervous system (CNS). During SSPE, infectious virus is not present either in the CNS or other tissues, but it has proved possible, in some cases, to rescue a measles-like virus by cocultivation techniques. These viruses may differ from measles virus, and from each other, but no single, stable property differentiates them. Differences between various strains of measles virus are of a similar magnitude to those observed between SSPE and measles viruses. This chapter discusses experiments to differentiate these agents using monoclonal antibodies raised against purified measles virus Edmonston. In no case is an isolate of measles virus available from the acute phase of infection preceding the develoment of SSPE by the same patient. This event is modeled by using a tissue culture of Vero cells persistently infected with an SSPE virus “Lec,” and this system is compared to other carrier cultures. These persistent infections differ from any persistence, because they are maintained in the absence of an immune response and may provide an insight into the importance of that phenomenon in the development of SSPE.