Characterization of Mumps Virus Isolated in Saitama Prefecture, Japan, by Sequence Analysis of the SH Gene

Abstract

Mumps virus (MuV) strains isolated from cerebrospinal fluid and throat swabs from patients in Saitama Prefecture and Tokyo, Japan, from 1997 to 2000 were examined by analyzing the SH gene nucleotide sequence (316-nt). Eighteen of the 20 strains studied were divided into three genotypes, recognized as B, G, and H in previous reports. Two genotypes (G and H) are believed to be new in Japan. Two of the 20 strains belonged to none of the previously reported genotypes (A-I), but were closely related to two known strains, MP94-H and Lougl/UK97. We propose that the two strains identified in this study together with the previously reported strains, MP94-H and Lougl/UK97, form a new genotype, designated J, based on the divergence of the SH gene nucleotide sequences between these four strains and other strains reported (genotypes A-I). Our results also suggest that more than two genotypes circulated in Saitama Prefecture from 1997 to 1999, but only one, genotype G, was in evidence in 2000. Genotype B was earlier reported as the predominant strain in Japan, but it became undetectable by the year 2000. These results provide important epidemiological data on mumps in Japan.

Characterization of the F Gene of Contemporary Mumps Virus Strains Isolated in Japan

“…The phylogenetic relation based on the F gene of other genotypes is not yet clear. On the other hand, we have reported the first isolation of MuV strains of 3 different genotypes in Japan during a recent mumps epidemic and outbreaks in Saitama Prefecture; genotype G was found in 1999 and 2000, H was found in 1997, and J which we proposed as a new genotype was found in 1997 and 1999 (23). Those results suggested that the mumps epidemic in the year 2000 was caused by genotype G strains (23).…”

“…One purpose of this study is to investigate MuV genotypes circulating in the prefecture since 2000, and to provide better characterization of the F gene of strains isolated in recent years in Japan. Another purpose is to confirm that the genotype proposed as J in our previous study (23) is different from genotype J designated by Tecle et al (21), and to rename the genotype we found to eliminate confusion. First, in the present study, we analyzed the SH gene of MuV strains isolated in Saitama Prefecture from 1997 to 2001 and other reported strains including genotype J identified by Tecle et al Then, we compared the phylogenetic analyses of the F gene among different genotypes and the alignments of deduced amino acid sequences obtained in this study to previously reported strains, especially those isolated in Japan.…”

“…On the other hand, we have reported the first isolation of MuV strains of 3 different genotypes in Japan during a recent mumps epidemic and outbreaks in Saitama Prefecture; genotype G was found in 1999 and 2000, H was found in 1997, and J which we proposed as a new genotype was found in 1997 and 1999 (23). Those results suggested that the mumps epidemic in the year 2000 was caused by genotype G strains (23). One purpose of this study is to investigate MuV genotypes circulating in the prefecture since 2000, and to provide better characterization of the F gene of strains isolated in recent years in Japan.…”

“…The clinical specimens comprised cerebrospinal fluid (CSF) and throat swabs (TS), and were collected from clinics and hospitals in Saitama Prefecture during 1997-2001. Virus isolation and identification were performed using cell cultures and anti-MuV antibodies (Denka Seiken Co., Ltd., Tokyo) as previously described (23). The origins of the strains used in this study are shown in Table 1.…”

“…The procedures for viral RNA extraction, cDNA synthesis, PCR amplification and nucleotide sequencing of the SH gene have been described previously (23). For analysis of the F gene, PCR amplification using primer set MOϩ and SHϪ described by Kashiwagi et al (6) was performed as follows: after denaturation for 5 min at 95 C, 30 cycles of 1 min at 95 C, 1.5 min at 50 C, 2 min at 72 C, and a final extension for 15 min at 72 C (6).…”