Molecular identification of two genotypes of mumps virus causing two regional outbreaks in Asturias, Spain

Abstract Background In spite of universal vaccination, several sporadic cases of mumps infection, which could produce outbreaks, are detected every year in different countries. Objective Mumps virus strains causing two regional outbreaks in Asturias (Spain) were phylogenetically characterized. Study design Mumps virus strains, which were detected in samples from patients belonging to two regional outbreaks in Asturias, were characterized by sequencing of the SH gene and further alignment to homologous sequences of representative strains of the different mumps genotypes. Results Two different strains (Ast/SP02 and Ast/SP07) were isolated. Sequence analysis revealed that while Ast/SP02 belonged to genotype H, Ast/SP07 was phylogenetically close to UK02-19, a reference strain for a new genotype. Both strains belonged to different genotypes from those used in the vaccination (Jeryl-Lynn strain is genotype A). Conclusion Mumps virus strains different from those used in vaccination program can cause mumps outbreaks even in vaccinated patients.