Summary auto-generated
This study characterized the genetic diversity of mumps virus by analyzing the small hydrophobic (SH) protein gene in 21 isolates collected from Sweden and Japan over 25 years. Using nucleotide sequencing and phylogenetic analysis, researchers identified five distinct genotypes (A through E) of mumps virus. Genotypes A, C, D, and E were found in Europe, while only genotype B was identified in Japan across all nine Japanese strains examined. Each genotype possessed characteristic amino acid signature sequences, particularly a distinctive three-amino-acid motif at positions 28-30 (TIL for type A, IIS for B, VVS for C, IIL for D, and SLS for E). The study revealed temporal and geographical patterns: Stockholm isolates from the 1970s belonged exclusively to genotype D, while later isolates (1980s-1990s) contained genotypes C and D, with one genotype A case. The SH protein gene showed greater sequence heterogeneity than other mumps virus genes previously analyzed. The findings suggest dynamic circulation of different genotypes in Europe over time, contrasting sharply with Japan's single-genotype dominance, indicating distinct viral epidemiology between regions.
Key findings
- Five conserved mumps virus genotypes (A-E) were identified based on SH protein gene sequences, with genotypes A, C, D, and E circulating in Europe and genotype B exclusively in Japan
- Each genotype possesses a characteristic three-amino-acid signature motif at positions 28-30 that clearly differentiates them from each other
- Different genotypes co-circulated in Stockholm at different time periods, with genotype D dominant in the 1970s and genotypes C/D appearing 15 years later
- The SH gene exhibits greater nucleotide sequence heterogeneity compared to other mumps virus genes (P, F, and HN proteins) previously analyzed
- All nine Japanese mumps virus strains isolated over 25 years belonged exclusively to genotype B, suggesting limited viral diversity and distinct epidemiology in Japan compared to Europe
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Abstract
Twenty-one different mumps virus isolates from Sweden and Japan collected over 25 years were compared by nucleotide sequence analysis of the small hydrophobic (SH) protein gene, and the deduced 57 amino acid sequences of the coding part of the gene were aligned with published sequences of viral isolates from the USA, the UK, Sweden and Japan. Five genotypes were found which, in accordance with previously used nomenclature, were named A to E. Genotypes A, C, D and E were found in Europe and genotype B was found in Japan. Amino acid signature sequence motifs specific for each genotype were identified. A triplet of three amino acids at positions 28-30 was the most characteristic. Different genotypes can circulate simultaneously in a given geographical location. In Stockholm, genotypes A and D or C and D were found over different time periods. In contrast, only genotype B was found in Japan.