engleski

Mumps neurovirulence testing – an obstacle in development of a safe mumps vaccine

Mumps is an acute communicable respiratory infection, caused by mumps virus (family Paramyxoviridae). While its most prominent symptom, parotitis, is relatively benign, more serious reactions such as meningitis or encephalitis occur in approx. 1- 10% of cases. These complications arise because of the highly neurotropic nature of the virus: in approx. 65% of cases infection of the central nervous system occurs. All currently available mumps vaccines are based on live attenuated strains and are usually given as part of tricomponent MMR vaccine (measles-mumps-rubella). Some mumps vaccine strains are insufficiently attenuated and although neurological side effects occur only in very small percentage of vaccinees, they add to public reluctance to vaccination and have even lead to cessation of mumps vaccination in some countries (e.g. Japan). Because of the neurovirulent properties of wild-type mumps viruses, testing of live mumps vaccines for neurovirulence is required by national regulatory organizations. Currently, there are two main methods for mumps neurovirulence testing: 1) inoculation of monkeys and measurement of following inflammatory reactions and description of histopathological changes ; 2) intracerebral inoculation of newbourn rats and measurement of hydrocephalus that develops during inspection period of 30-days. Neither of two methods gives accurate prediction of strains' neurovirulence potential in humans. Monkey-based test is extremely expensive and often inaccurate ; rat-based test seems to have greater predictive value but it is very imprecise.

mumps ; virus neurovirulence ; test on animals ; alternative methods ; 3R principle

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