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PubMed | Japan National Institute of Infectious Diseases, Nagoya City University, Yamaguchi Prefectural Institute of Public Health and Environment and Ehime Prefectural Institute of Public Health and Environmental Science
Type: Journal Article | Journal: Microbiology and immunology | Year: 2016

Noroviruses cause acute gastroenteritis. Since multiple genotypes of norovirus co-circulate in humans, changing the genotype composition and eluding host immunity, development of a polyvalent vaccine against norovirus in which the genotypes of vaccine strains match the major strains in circulation in the target season is desirable. However, this would require prediction of changes in the genotype composition of circulating strains. A fitness model that predicts the proportion of a strain in the next season from that in the current season has been developed for influenza A virus. Here, such a fitness model that takes into account the fitness effect of herd immunity was used to predict genotype compositions in norovirus seasons in Japan. In the current study, a model that assumes a decline in the magnitude of cross immunity between norovirus strains according to an increase in the divergence of the major antigenic protein VP1 was found to be appropriate for predicting genotype composition. Although it is difficult to predict the proportions of genotypes accurately, the model is effective in predicting the direction of change in the proportions of genotypes. The model predicted that GII.3 and GII.4 may contract, whereas GII.17 may expand and predominate in the 2015-2016 season. The procedure of predicting genotype compositions in norovirus seasons described in the present study has been implemented in the norovirus forecasting system (NOROCAST).


PubMed | Oita Prefectural Institute of Health and Environment, Pharmaceutical and Environmental science Center, Okayama Prefectural Institute for Public Health and Environmental Science, Hyogo Prefectural Institute of Public Health and Consumer science and 13 more.
Type: Journal Article | Journal: The Journal of infectious diseases | Year: 2015

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne acute infectious disease caused by the SFTS virus (SFTSV). SFTS has been reported in China, South Korea, and Japan as a novel Bunyavirus. Although several molecular epidemiology and phylogenetic studies have been performed, the information obtained was limited, because the analyses included no or only a small number of SFTSV strains from Japan.The nucleotide sequences of 75 SFTSV samples in Japan were newly determined directly from the patients serum samples. In addition, the sequences of 7 strains isolated in vitro were determined and compared with those in the patients serum samples. More than 90 strains that were identified in China, 1 strain in South Korea, and 50 strains in Japan were phylogenetically analyzed.The viruses were clustered into 2 clades, which were consistent with the geographic distribution. Three strains identified in Japan were clustered in the Chinese clade, and 4 strains identified in China and 26 in South Korea were clustered in the Japanese clade.Two clades of SFTSV may have evolved separately over time. On rare occasions, the viruses were transmitted overseas to the region in which viruses of the other clade were prevalent.


PubMed | Hokkaido Institute of Public Health, Fukuoka Institute of Health Environmental, Japan Institute for Environmental Sciences, Chiba Prefectural Institute of Public Health and 7 more.
Type: | Journal: Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology | Year: 2016

An easy and reliable assay for detection of the rubella virus is required to strengthen rubella surveillance. Although a TaqMan RT-PCR assay for detection of the rubella virus has been established in Japan, its utility for diagnostic purposes has not been tested.To allow introduction of the TaqMan RT-PCR into the rubella surveillance system in Japan, the sensitivity of the assay was determined using representative strains for all genotypes and clinical specimens.The detection limits of the method for individual genotypes were examined using viral RNA extracted from 13 representative strains. The assay was also tested at 10 prefectural laboratories in Japan, designated as local reference laboratories for measles and rubella, to allow nationwide application of the assay.The detection limits and amplification efficiencies of the assay were similar among all the representative strains of the 13 genotypes. The TaqMan RT-PCR could detect approximately 90% of throat swab and urine samples taken up to 5days of illness. These samples were determined positive by a highly sensitive nested RT-PCR.The TaqMan RT-PCR could detect at least 10 pfu of rubella virus. Although the sensitivity was somewhat lower than that of the conventional nested RT-PCR, the TaqMan RT-PCR could be more practical to routine tests for rubella laboratory diagnosis and detection in view of the rapid response and reducing risks of contamination.


Ikebe T.,Japan National Institute of Infectious Diseases | Tominaga K.,Yamaguchi Prefectural Institute of Public Health and Environment | Shima T.,Toyama Institute of Health | Okuno R.,Japan National Institute of Public Health | And 10 more authors.
Epidemiology and Infection | Year: 2015

Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock, multi-organ failure, and high mortality. In Japan, appropriate notification measures based on the Infectious Disease Control law are mandatory for cases of STSS caused by β-haemolytic streptococcus. STSS is mainly caused by group A streptococcus (GAS). Although an average of 60-70 cases of GAS-induced STSS are reported annually, 143 cases were recorded in 2011. To determine the reason behind this marked increase, we characterized the emm genotype of 249 GAS isolates from STSS patients in Japan from 2010 to 2012 and performed antimicrobial susceptibility testing. The predominant genotype was found to be emm1, followed by emm89, emm12, emm28, emm3, and emm90. These six genotypes constituted more than 90% of the STSS isolates. The number of emm1, emm89, emm12, and emm28 isolates increased concomitantly with the increase in the total number of STSS cases. In particular, the number of mefA-positive emm1 isolates has escalated since 2011. Thus, the increase in the incidence of STSS can be attributed to an increase in the number of cases associated with specific genotypes. Copyright © Cambridge University Press 2014.


PubMed | Yamaguchi Prefectural Institute of Public Health and Environment, The University of Shimane, Japan National Institute of Infectious Diseases, National Hospital Organization Disaster Medical Center and Shimane Prefectural Central Hospital
Type: Case Reports | Journal: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy | Year: 2015

Streptococcal toxic shock syndrome is a severe infectious disease. We report a Japanese case of Streptococcal toxic shock syndrome caused by a highly mucoid strain of Streptococcus pyogenes. A 31-year old female with shock vital sign presented at a tertiary medical center. Her left breast was necrotizing and S. pyogenes was detected by Immunochromatographic rapid diagnostic kits. Intensive care, including administration of antibiotics and skin debridement, was performed. After 53 days in our hospital, she was discharged. The blood cultures and skin swab cultures all grew S. pyogenes which displayed a highly mucoid morphology on culture media. In her course of the disease, the Streptococcus strain had infected two other family members. All of the strains possessed the T1 and M1 antigens, as well as the emm1.0 gene. As for fever genes, the strains were all positive for speA, speB, and speF, but negative for speC. All of the strains exhibited and the same pattern in PFGE with the SfiI restriction enzyme. The strain might have spread in the local area by the data from the Japanese Infectious Disease Surveillance Center. Immunochromatographic rapid diagnostic kits are very useful for detecting S. pyogenes. However, they can not be used to diagnose severe streptococcul disease by highly mucoid strain alone. Careful observation of patients and colony morphology are useful methods for diagnosing severe streptococcal disease by highly mucoid strain.


PubMed | Yamaguchi Prefectural Institute of Public Health and Environment, Japan National Institute of Infectious Diseases, Osaka Prefectural Institute of Public Health, Hokkaido Institute of Public Health and Japan Institute for Environmental Sciences
Type: | Journal: Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases | Year: 2016

Rotaviruses C (RVCs) circulate worldwide as an enteric pathogen in both humans and animals. Most studies of their genetic diversity focus on the VP7 and VP4 genes, but the complete genomes of 18 human RVCs have been described in independent studies. The genetic background of the Far East Asian RVCs is different than other human RVCs that were found in India and Bangladesh. Recently, a RVC detected in 2010 in South Korea had genetic background similar to the Indian-Bangladeshi RVCs. This study was undertaken to determine the whole genome of eight Japanese RVCs detected in 2005-2012, and to compare them with other human and animal global RVCs to better understand the genetic background of contemporary Far East Asian RVC. By phylogenetic analysis, the human RVCs appeared to be distinct from animal RVCs. Among human RVCs, three lineage constellations had prolonged circulation. The genetic background of the Far East Asian RVC was distinguished from Indian-Bangladeshi RVC as reported earlier. However, we found one Japanese RVC in 2012 that carried the genetic background of Indian-Bangladeshi RVC, whereas the remaining seven Japanese RVCs carried the typical genetic background of Far East Asian RVC. This is the first report of the Indian-Bangladeshi RVC in Japan. With that observation and the reassortment event of human RVCs in Hungary, our study indicates that the RVCs are spreading from one region to another.


Okuda M.,Yamaguchi University | Hinoda Y.,Yamaguchi University | Okayama N.,Yamaguchi University | Suehiro Y.,Yamaguchi University | And 5 more authors.
Pediatric Diabetes | Year: 2011

Background: The association between the fat mass- and obesity-associated (FTO) gene and a predisposition to obesity is inconsistent in adult Asian populations. We investigated the association of the FTO gene with weight status in Japanese children and adolescents. Design/setting: Nested case-control study and 3-yr longitudinal study - In the Shunan Child Cohort Study, fifth and eighth grade students attending all schools of Shunan completed the questionnaires. Overweight, including obesity, was defined as a percentage of overweight of 20% or in accordance with the International Obesity Task Force. We recruited 133 obese subjects and randomly selected controls from the 2006 cohort. We genotyped three FTO single nucleotide polymorphisms (SNPs): rs3751812, rs9939609, and rs1558902. Results: The three genotyped SNPs were in tight linkage disequilibrium, with the exception of one case. The minor SNP allele of rs3751812 conferred a predisposition to obesity, and its odds ratio was 2.2 [95% confidence interval (CI), 1.5-3.4] in the additive model and 2.7 (95% CI, 1.6-4.4) in the dominant model (p < 0.001). Although blood parameters and some lifestyle behaviors were significantly different between the cases and controls (p < 0.01), these traits were not significantly different among the genotypes. In addition, we did not find an association between the genotypes and body mass index change during the 3 yr. Conclusion: The FTO gene is associated with the early onset of overweight in the Japanese population as well as in European populations. The results suggest that obesity-related risk factors in fifth and eighth graders appear because of their overweight status. © 2011 John Wiley & Sons A/S.

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