J.E. Echevarría, A. Castellanos, J.C. Sanz, M.V. Martínez de Aragón, I. Peña Rey, M. Mosquera , F. de Ory, E. Royuela
Unidad de Aislamiento y
Detección de Virus, Servicio de Microbiología Diagnóstica, Centro
Nacional de Microbiología, Instituto de Salud Carlos III, Ctra. MajadahondaPozuelo
s/n, 28220 Majadahonda, Madrid, Spain
Although mumps virus (MV) is considered antigenically monotypic, twelve different genotypes of MV based on genetic variation in the SH gene (A to L) are currently recognised by the WHO. Both dominance of a single genotype and co-circulation of different genotypes in the same geographical area, as well as temporal replacement of genotypes have been described in different countries. The different histories of genotype importation, variations in vaccine coverage and the use of different vaccine strains in each country results in a complex picture that could be the cause of the different geographical patterns of mumps virus genotype circulation observed in different countries. Lack of full cross-protection between different genotypes has been reported and has been suggested as a cause of vaccine failure, especially for vaccine strains belonging to genotype A, which is genetically distant to the remaining genotypes that include most of the currently circulating wild strains. Finally, a differential ability to invade the neural system has been suggested for some particular strains belonging to genotype D.