The mumps virus neurovirulence safety test in rhesus monkeys: A comparisonof mumps virus strains

Wild type mumps viruses are highly neurotropic and a frequent cause of asep tic meningitis in unvaccinated humans. To test whether attenuated mumps vir uses used in the manufacture of mumps vaccines have neurovirulent propertie s, a monkey neurovirulence safety test (MNVT) is performed. However, result s with several mumps virus MNVTs have raised questions as to whether the te st can reliably discriminate neurovirulent from nonneurovirulent mumps viru s strains, Here, various mumps virus strains representing a wide range of n europathogenicity were tested in a standardized MNVT A trend of higher neur ovirulence scores was observed in monkeys inoculated with wild type mumps v irus versus vaccine strains, although differences were not statistically si gnificant. Results indicated the need for further examination and refinemen t of the MNVT or for development of alternative MNVTs.