Properties of a measles virus neuropathic for rhesus monkeys

Summary A highly hamster brain adapted strain of measles virus, capable of producing encephalitis in monkeys, inoculated into Vero cell cultures replicated in a suppressed growth cycle. No virus was released into the medium and the infected cells lacked specific virus determinants for hemadsorption. A complete replicative cycle was achieved after six subcultures of Vero cells and was accompanied by a partial drop in neurovirulence. However, hamster neuropathogenicity persisted throughout 26 Vero passages and was markedly higher than in non-brain passaged strains. High neurovirulence was associated with pronounced giant cell cytopathic effect and thermolability. On continuous passage these three properties dissociated at different rates indicating that they are independent properties of measles virus. The importance of their coincidence for the initiation of an encephalitic process in the brain of primates is stressed.