Characterization of five conserved genotypes of the mumps virus small hydrophobic (SH) protein gene

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.