A Variant of Venezuelan Equine Encephalomyelitis Virus Attenuated for Mice and Monkeys

Summary Venezuelan equine encephalomyelitis virus obtained from chronically infected L cell cultures showed a marked loss in virulence upon peripheral inoculation into mice and monkeys compared to parent virus strains. The new avirulent strain elicited high levels of neutralizing antibody in monkeys and protected both mice and monkeys against an intracerebral challenge inoculation of 105 and 105.3 LD50 respectively. The successful immunization resulted after the administration of one small dose of attenuated virus given by peripheral routes.