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1.
J Clin Virol ; 160: 105377, 2023 03.
Article in English | MEDLINE | ID: mdl-36682339

ABSTRACT

BACKGROUND: Since the first isolation of rubella virus (RuV) in 1962, comprehensive data regarding the quantitative evaluation of RuV shedding remain unavailable. In this study, we evaluated the shedding of viral RNA and infectious virus in patients with acute RuV infection. STUDY DESIGN: We analyzed 767 specimens, including serum/plasma, peripheral blood mononuclear cells (PBMCs), throat swabs, and urine, obtained from 251 patients with rubella. The viral RNA load and the presence of infectious RuV were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and virus isolation. RESULTS: Virus excretion peaked 0-2 days after rash onset and decreased over time. The median viral RNA load dropped to an undetectable level on day 3 after rash onset in serum/plasma, day 2 in PBMCs, days 10-13 in throat swabs, and days 6-7 in urine. Infectious virus could be isolated for up to day 2 after rash onset in serum/plasma, day 1 in PBMCs, days 8-9 in throat swabs, and days 4-5 in urine. The minimum viral RNA load that allowed virus isolation was 961 copies/mL in serum/plasma, 784 copies/mL in PBMCs, 650 copies/mL in throat swabs, and 304 copies/mL in urine. A higher viral RNA load indicated a higher likelihood of the presence of infectious virus. CONCLUSION: These findings would contribute to improve algorithms for rubella surveillance and diagnosis. In addition, this study indicates that the results of RT-qPCR enable efficient rubella control by estimating candidate patients excreting infectious virus, which could help prevent viral transmission at an early stage and eliminate rubella ultimately.


Subject(s)
Exanthema , Rubella , Humans , Rubella virus/genetics , RNA, Viral/genetics , Leukocytes, Mononuclear , Rubella/diagnosis , Virus Shedding
2.
Sci Rep ; 13(1): 939, 2023 01 18.
Article in English | MEDLINE | ID: mdl-36653400

ABSTRACT

In general, it is known that extreme climatic conditions such as El Niño and positive Indian Ocean Dipole (IOD+) cause prolonged drought in Indonesia's tropical peatlands so that groundwater levels (GWL) drop and peat is prone to fire. However, 27 years of GWL measurements in Central Kalimantan peat forests show the opposite condition, where the lowest GWL occurs several weeks before El Niño and after IOD+ reaches its peaks. We show that the dropped sea surface temperature anomaly induced by anomalously easterly winds along the southern Java-Sumatra occurs several weeks before the GWL drop to the lowest value. Local rainfall decreased, and GWL dropped sharply by 1.0 to 1.5 m, during the super El Niño events in 1997/98 and 2015, as well as remarkable events of IOD+ in 2019. It is suggested that the tropical peatland ecohydrological system (represented by the GWL), El Niño Southern Oscillation (ENSO), and IOD+ are teleconnected. Hence, monitoring GWL variability of peatland over the IMC is a possibility an alert for extreme climate events associated with El Niño and/or moderate IOD+.


Subject(s)
El Nino-Southern Oscillation , Groundwater , Indonesia , Seasons , Indian Ocean , Soil
3.
Wilderness Environ Med ; 32(1): 88-91, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33516622

ABSTRACT

We report a case of prolonged motivational deficit as a sequela of high altitude cerebral edema (HACE), the most severe form of neuropsychiatric dysfunction arising from traveling to high altitude. Magnetic resonance imaging of the brain showed hyperintense lesions in the globi pallidi bilaterally on T2-weighted images. Single-photon emission computed tomography showed hypoperfusion in dorsolateral and orbital prefrontal cortices bilaterally and in the anterior cingulate cortex. This case suggests that a prolonged motivational deficit can occur in patients with HACE. The case may also suggest that HACE can cause network disturbances between the prefrontal cortex and the globi pallidi.


Subject(s)
Altitude Sickness/complications , Apathy , Brain Edema/complications , Adult , Brain/diagnostic imaging , Brain/pathology , Humans , Male
5.
Ann Gen Psychiatry ; 19: 49, 2020.
Article in English | MEDLINE | ID: mdl-32944056

ABSTRACT

BACKGROUND: Valproate-induced hypothyroidism is a rare condition and has been considered asymptomatic. Here, we report a case of bipolar I disorder who developed symptomatic valproate-induced hypothyroidism. CASE PRESENTATION: A 44-year-old woman with bipolar I disorder complained of severe fatigue after starting valproate. She showed a hormonal pattern of central hypothyroidism. Thyroid autoantibodies were negative, and no pituitary abnormality was seen on magnetic resonance imaging. After stopping valproate, her severe fatigue rapidly improved with normalizing thyroid function. CONCLUSIONS: Our case suggests that valproate-induced hypothyroidism should be considered when patients complain of excessive fatigue under treatment with valproate.

6.
Sci Rep ; 10(1): 13496, 2020 08 11.
Article in English | MEDLINE | ID: mdl-32782312

ABSTRACT

Influenza virus, respiratory syncytial virus, and human metapneumovirus commonly cause acute upper and lower respiratory tract infections, especially in children and the elderly. Although rapid antigen detection tests for detecting these infections have been introduced recently, these are less sensitive than nucleic acid amplification tests. More recently, highly sensitive point-of-care testings (POCTs) have been developed based on nucleic acid amplification tests, which are easy to use in clinical settings. In this study, loop-mediated isothermal amplification (LAMP)-based POCT "Simprova" to detect influenza A and B viruses, respiratory syncytial virus, and human metapneumovirus was developed. Simprova system is fully automated and does not require skilled personnel. In addition, positive results can be achieved faster than with PCR. In this study, the accuracy of the POCT was retrospectively analyzed using 241 frozen stocked specimens. Additionally, the usability of the Simprova at clinical sites was assessed in a prospective clinical study using 380 clinical specimens and compared to those of real-time PCR and rapid antigen detection test. The novel LAMP-based POCT demonstrated high sensitivity and specificity in characterizing clinical specimens from patients with influenza-like illnesses. The Simprova is a powerful tool for early diagnosis of respiratory viral infections in point-of-care settings.


Subject(s)
Metapneumovirus/isolation & purification , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Orthomyxoviridae/isolation & purification , Respiratory Syncytial Viruses/isolation & purification , Adolescent , Automation , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Male , Metapneumovirus/genetics , Orthomyxoviridae/genetics , Respiratory Syncytial Viruses/genetics
7.
Sci Rep ; 10(1): 963, 2020 01 22.
Article in English | MEDLINE | ID: mdl-31969658

ABSTRACT

Mammalian orthoreovirus (MRV), also known as reovirus, was discovered in the 1950s and became the first reported segmented double-stranded RNA virus. MRVs have since been found in a variety of animal species, including humans. However, reports on MRV infections are scarce due to the rarity of their symptomatic occurrence. In Japanese surveillance studies, MRVs have been detected as gastrointestinal pathogens since 1981, with a total of 135 records. In Osaka City, Japan, MRV was first isolated in 1994 from a child with meningitis, and then in 2005 and 2014 from children with gastroenteritis. Here, we conducted the first molecular characterization of human MRV isolates from Japan and identified a novel human reovirus strain belonging to MRV type 2, designated the MRV-2 Osaka strain. This strain, with all three isolates classified, is closely related to MRV-2 isolates from sewage in Taiwan and is relatively close to an MRV-2 isolate from a bat in China. Our data suggest that the MRV-2 Osaka strain, which has circulated amongst humans in Japan for at least two decades, has spread internationally.


Subject(s)
Genome, Viral , Orthoreovirus, Mammalian/isolation & purification , Reoviridae Infections/virology , Child , Humans , Japan , Orthoreovirus, Mammalian/genetics
9.
J Med Virol ; 91(12): 2101-2107, 2019 12.
Article in English | MEDLINE | ID: mdl-31368535

ABSTRACT

Norovirus (NoV) is a major cause of viral gastroenteritis, and GII.4 has been the predominant genotype worldwide since the mid-1990s. During the 2014 to 2015 winter, a rare genotype, NoV GII.17, emerged and became prevalent mainly in East Asia. Over the past two decades, NoV molecular surveillance in Osaka City, Japan, has revealed that NoV GII.17 was detected for the first time in February 2001 and that NoV GII.17-associated outbreaks remarkably increased during the 2014 to 2015 season, with higher incidence recorded in January to March 2015. Genetic analysis indicated that 28 GII.17 outbreak strains were closely related to the novel GII.P17-GII.17 variants represented by the Kawasaki308/2015/JP strain, similar to that in other regions. Statistical analysis showed that NoV GII.17 infections were more common in adults than GII.3 and GII.4 infections, suggesting that the affected adults most likely did not have antibodies against NoV GII.17 and the novel GII.17 variant had recently appeared. Regarding transmission, food was one of the most important factors involved in the spread of NoV GII.17 among adults; 61% of GII.17 outbreaks were foodborne, with oysters being the most common vehicle. Interplay between pathogens, hosts, and environmental factors was considered to be important in the 2014 to 2015 NoV GII.17 epidemic.


Subject(s)
Caliciviridae Infections/epidemiology , Caliciviridae Infections/virology , Disease Outbreaks , Gastroenteritis/epidemiology , Norovirus/genetics , Adult , Animals , Antibodies, Viral/blood , Caliciviridae Infections/transmission , Child , Cities/epidemiology , Foodborne Diseases/epidemiology , Foodborne Diseases/virology , Gastroenteritis/virology , Genotype , Humans , Incidence , Japan/epidemiology , Ostreidae/virology , Phylogeny , Seasons
10.
Jpn J Infect Dis ; 72(6): 426-428, 2019 Nov 21.
Article in English | MEDLINE | ID: mdl-31257241

ABSTRACT

Dengue fever (DF) is a mosquito-borne disease and a significant global public health problem. Although a few serological surveys in the literature suggest endemic DF in many parts of Africa, DF cases in these countries are generally underreported because of the lack of diagnostic testing and systematic surveillance; thus, little is known about the phylogenetic profile of circulating strains. In April 2015, DF was diagnosed in a Japanese national returning from the Democratic Republic of the Congo (DRC). Dengue virus 1 (DENV-1) RNA was detected in the patient's serum sample using real-time reverse transcription PCR. Phylogenetic analysis of the E gene revealed that the detected DENV-1 strain was classified as genotype V and was closely related, with 100% nucleotide identity, to the strain causing the 2013 DF epidemic in Angola, which is located directly south of the DRC. This is the first report to characterize the circulating DENV strain in the DRC, and the findings indicate that the DENV-1 strain causing the 2013 DF epidemic in Angola was also circulating in the DRC in 2015.


Subject(s)
Dengue Virus/genetics , Dengue/diagnosis , Travel-Related Illness , Democratic Republic of the Congo , Dengue/virology , Dengue Virus/isolation & purification , Genotype , Humans , Japan , Male , Middle Aged , Phylogeny , RNA, Viral/genetics , Viral Envelope Proteins/genetics
11.
Emerg Infect Dis ; 25(9): 1782-1784, 2019 09.
Article in English | MEDLINE | ID: mdl-31237836

ABSTRACT

The largest outbreak of dengue fever in Tanzania is ongoing. Dengue virus type 1 was diagnosed in a traveler who returned from Tanzania to Japan. In phylogenetic analysis, the detected strain was close to the Singapore 2015 strain, providing a valuable clue for investigating the dengue outbreak in Tanzania.


Subject(s)
Dengue Virus/isolation & purification , Dengue/diagnosis , Adult , Dengue/drug therapy , Dengue/virology , Dengue Virus/genetics , Humans , Japan , Male , Phylogeny , Tanzania , Travel
12.
Jpn J Infect Dis ; 72(5): 334-336, 2019 Sep 19.
Article in English | MEDLINE | ID: mdl-31061358

ABSTRACT

The second largest epidemic of hand, foot, and mouth disease since 1982 occurred in 2017, which involved 6,173 cases in Osaka City, Japan. The main causative agent was coxsackievirus A6 (CV-A6). Phylogenetic analysis revealed that the detected CV-A6 strains belonged to genetic groups A3 and A4 in clade A.


Subject(s)
Enterovirus/classification , Enterovirus/isolation & purification , Epidemics , Genotype , Hand, Foot and Mouth Disease/epidemiology , Child, Preschool , Cities/epidemiology , Enterovirus/genetics , Female , Humans , Infant , Japan/epidemiology , Male
13.
Viruses ; 11(3)2019 03 04.
Article in English | MEDLINE | ID: mdl-30836639

ABSTRACT

Rhinoviruses (RVs) are classified into three species: RV-A, B, and C. Unlike RV-A and -B, RV-C cannot be propagated using standard cell culture systems. In order to isolate RV-Cs from clinical specimens and gain a better understanding of their biological properties and pathogenesis, we established air⁻liquid-interface (ALI) culture methods using HBEC3-KT and HSAEC1-KT immortalized human airway epithelial cells. HBEC3- and HSAEC1-ALI cultures morphologically resembled pseudostratified epithelia with cilia and goblet cells. Two fully sequenced clinical RV-C isolates, RV-C9 and -C53, were propagated in HBEC3-ALI cultures, and increases in viral RNA ranging from 1.71 log10 to 7.06 log10 copies were observed. However, this propagation did not occur in HSAEC1-ALI cultures. Using the HBEC3-ALI culture system, 11 clinical strains of RV-C were isolated from 23 clinical specimens, and of them, nine were passaged and re-propagated. The 11 clinical isolates were classified as RV-C2, -C6, -C9, -C12, -C18, -C23, -C40, and -C53 types according to their VP1 sequences. Our stable HBEC3-ALI culture system is the first cultivable cell model that supports the growth of multiple RV-C virus types from clinical specimens. Thus, the HBEC3-ALI culture system provides a cheap and easy-to-use alternative to existing cell models for isolating and investigating RV-Cs.


Subject(s)
Cell Differentiation , Enterovirus/growth & development , Epithelial Cells/virology , Virus Cultivation , Cell Count , Cell Line, Transformed , Enterovirus/genetics , Enterovirus/physiology , Humans , Respiratory System/cytology
14.
J Virol Methods ; 267: 53-58, 2019 05.
Article in English | MEDLINE | ID: mdl-30831121

ABSTRACT

Influenza virus and respiratory syncytial virus cause acute upper and lower respiratory tract infections, especially in children and the elderly. Early treatment for these infections is thought to be important, so simple and sensitive detection methods are needed for use at clinical sites. Therefore, in this study, real-time reverse transcription loop-mediated isothermal amplification assays with quenching primer for influenza virus and respiratory syncytial virus were developed. Evaluation of a total of 113 clinical specimens compared to real-time RT-PCR assays showed that the novel assays could distinguish between the types and subtypes of influenza virus and respiratory syncytial virus and had 100% diagnostic specificity. The diagnostic sensitivity of each assay exceeded 85.0% and the assays showed sufficient clinical accuracy. Furthermore, positive results could be obtained in around 15 min using the novel assays in cases with high concentrations of virus. The developed assays should be useful for identifying influenza virus and respiratory syncytial virus cases not only in experimental laboratories but also in hospital and quarantine laboratories.


Subject(s)
DNA Primers/genetics , Orthomyxoviridae/isolation & purification , Respiratory Syncytial Virus, Human/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction , Humans , Influenza, Human/diagnosis , Influenza, Human/virology , Respiratory Syncytial Virus Infections/diagnosis , Respiratory Syncytial Virus Infections/virology , Respiratory Tract Infections/diagnosis , Respiratory Tract Infections/virology , Sensitivity and Specificity , Temperature
15.
J Med Virol ; 91(7): 1232-1238, 2019 07.
Article in English | MEDLINE | ID: mdl-30735248

ABSTRACT

Human rhinoviruses (RVs) belong to the genus Enterovirus of the family Picornaviridae, and are classified into RV-A, -B, and -C species. Two assays were developed to detect RVs by a real-time fluorescent reverse transcription loop-mediated isothermal amplification method: one was designed based on the 5'-untranslated regions (UTRs) of RV-A and -B, and the other was designed based on the 5'-UTR of RV-C. The competence of both assays for the diagnosis of RV infection was tested using isolated viruses and compared with real-time reverse transcription polymerase chain reaction assays on clinical specimens. Neither assay demonstrated cross-reactivity with other tested enteroviruses, and they detected 19 out of 21 tested RV-As and seven out of eight tested RV-Cs. The specificity of the assays was 100% for the detection of RVs and their sensitivity for RV-A and RV-C was 86.3% and 77.3%, respectively, on clinical specimens by the combined use of both assays. Considering that both developed assays were highly specific and detected the majority of recently circulating RVs, they are helpful for the diagnosis of RV infection. Consequently, the results generated by these assays will enhance the surveillance of respiratory illness and the study of the roles of RVs associated with clinical features and disease severity.


Subject(s)
Fluorescence , Molecular Diagnostic Techniques , Nucleic Acid Amplification Techniques/methods , Picornaviridae Infections/diagnosis , Rhinovirus/genetics , Temperature , 5' Untranslated Regions/genetics , DNA Primers , Humans , Picornaviridae Infections/virology , RNA, Viral/genetics , Real-Time Polymerase Chain Reaction , Sensitivity and Specificity
16.
J Oral Rehabil ; 46(4): 303-309, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30570153

ABSTRACT

BACKGROUND: No studies have addressed the effect of SR on somatosensory function in the oro-facial area. OBJECTIVES: The aim of this study was to investigate the effect of sleep restriction (SR) on the somatosensory perception of the tip of the tongue. MATERIALS AND METHODS: Using a crossover study design, 13 healthy participants took part in a random order, to a two arms experiments: the SR and control/no SR-arms. For all participants, the Epworth Sleepiness Scale (ESS) was used to assess sleepiness and mechanical sensitivity, and pain detection threshold was estimated at the tongue tip and right thumb (as a body area control site). In the SR-arm of the study, on day one, we estimated sensory baseline perception and repeated tests on day two, after a night of voluntary SR, and on day 3, after a recovery night. In the second arm, same sensory tests were done but no SR was requested. RESULTS: Significantly more sleepiness was observed after SR in comparison with baseline and recovery testing days (P < 0.05). After SR, mechanical pain threshold on the tip of the tongue was significantly lower on day after SR (day 2) and a rebound, higher values, were observed on the third day (P < 0.05); no difference on thumb site. In the control arm, no SR and no significant differences between days were observed for all the variables of interest. CONCLUSIONS: The present results suggest that SR may affect somatosensory perception in the oro-facial area.


Subject(s)
Pain Threshold/physiology , Sensory Thresholds/physiology , Sleep Deprivation/physiopathology , Thumb/innervation , Tongue/innervation , Cross-Over Studies , Female , Healthy Volunteers , Humans , Male , Pain Measurement , Physical Stimulation , Reproducibility of Results , Thumb/physiology , Tongue/physiology , Young Adult
17.
Jpn J Infect Dis ; 71(2): 152-154, 2018 Mar 22.
Article in English | MEDLINE | ID: mdl-29279450

ABSTRACT

Measles is a highly contagious infection caused by the measles virus (MV). This study performed long-term surveillance in order to survey the prevalence of MV. A total of 417 patients diagnosed with or suspected of having measles were tested for MV between January 2007 and December 2016 in Osaka City, Japan. Reverse transcription-polymerase chain reaction-based testing of clinical specimens showed that 54 patients (12.9%) were MV-positive. An MV epidemic occurred in 2007, in which all detected MV strains were genotype D5, an epidemic strain in Japan at that time. The detected wild-type MV strains in sporadic or outbreak-associated cases since 2011 included genotypes D4, D8, B3, and H1. Three vaccine strains (all genotype A) were also detected. Children <10 years of age accounted for 90.0% of the MV-positive patients in 2007. In contrast, adults (≥ 20 years of age) accounted for the majority of MV-positive cases since 2011, as follows: 100%, 50%, 71.4%, 100%, and 87.5% of cases in 2011, 2013, 2014, 2015, and 2016, respectively. The recent high rate of two-dose MV vaccination coverage among children in Japan may have contributed to the reduced risk of MV infection and onset of measles in young persons.


Subject(s)
Measles virus/genetics , Measles/epidemiology , Adolescent , Adult , Aged , Child , Child, Preschool , Genotype , Humans , Infant , Infant, Newborn , Japan/epidemiology , Leukocytes, Mononuclear/virology , Middle Aged , Population Surveillance , Prevalence , RNA, Viral/analysis , RNA, Viral/genetics , Young Adult
18.
PLoS One ; 12(9): e0184335, 2017.
Article in English | MEDLINE | ID: mdl-28902862

ABSTRACT

The first upsurge of enterovirus D68 (EV-D68), a causative agent of acute respiratory infections (ARIs), in Japan was reported in Osaka City in 2010. In this study, which began in 2010, we surveyed EV-D68 in children with ARIs and analyzed sequences of EV-D68 strains detected. Real-time PCR of 19 respiratory viruses or subtypes of viruses, including enterovirus, was performed on 2,215 specimens from ARI patients (<10 years of age) collected between November 2010 and December 2015 in Osaka City, Japan. EV-D68 was identified in 18 enterovirus-positive specimens (n = 4 in 2013, n = 1 in 2014, and n = 13 in 2015) by analysis of viral protein 1 (VP1) or VP4 sequences, followed by a BLAST search for similar sequences. All EV-D68 strains were detected between June and October (summer to autumn), except for one strain detected in 2014. A phylogenetic analysis of available VP1 sequences revealed that the Osaka strains detected in 2010, 2013, and 2015 belonged to distinct clusters (Clades C, A, and B [Subclade B3], respectively). Comparison of the 5' untranslated regions of these viruses showed that Osaka strains in Clades A, B (Subclade B3), and C commonly had deletions at nucleotide positions 681-703 corresponding to the prototype Fermon strain. Clades B and C had deletions from nucleotide positions 713-724. Since the EV-D68 epidemic in 2010, EV-D68 re-emerged in Osaka City, Japan, in 2013 and 2015. Results of this study indicate that distinct clades of EV-D68 contributed to re-emergences of this virus in 2010, 2013, and 2015 in this limited region.


Subject(s)
Enterovirus D, Human/classification , Enterovirus D, Human/genetics , Enterovirus Infections/epidemiology , Enterovirus Infections/virology , Child , Child, Preschool , Communicable Diseases, Emerging/virology , Disease Outbreaks/statistics & numerical data , Female , Humans , Infant , Infant, Newborn , Japan/epidemiology , Male , Phylogeny , Respiratory Tract Infections/virology , Sequence Analysis, DNA , Urbanization , Viral Structural Proteins/genetics
19.
J Med Virol ; 89(12): 2116-2121, 2017 12.
Article in English | MEDLINE | ID: mdl-28771766

ABSTRACT

Hand, foot, and mouth disease (HFMD) is an acute febrile illness characterized by fever; sore throat; and vesicular eruptions on the hands, feet, and oral mucosa. Until 2010, HFMD was predominantly associated with enterovirus (EV) A71 and coxsackievirus (CV) A16 in Japan. In 2011, CV-A6 emerged as a primary causative agent, causing the largest HFMD epidemic in Japan since 1981. Since then, CV-A6 has caused large HFMD epidemics every 2 years. The phylogenetic analysis of complete Viral Protein 1 (VP1) sequences revealed that most CV-A6 strains detected from 2011 to 2015 in Osaka City were classified into a different clade compared with CV-A6 strains detected from 1999 until 2009. The majority of CV-A6 strains detected in 2011 and most CV-A6 strains detected from 2013 to 2015 were mainly divided into two distinct genetic groups. Each epidemic strain carried unique amino acid substitutions in the presumed DE, EF, and GH loops of the VP1 protein that is exposed on the surface of the virion. There is a possibility that the appearance of substitutions on the surface of the virion and an accumulation of a susceptible population are significant factors in recent HFMD epidemics.


Subject(s)
Enterovirus A, Human/classification , Enterovirus A, Human/genetics , Epidemics , Hand, Foot and Mouth Disease/epidemiology , Hand, Foot and Mouth Disease/virology , Disease Outbreaks , Enterovirus A, Human/isolation & purification , Epidemiological Monitoring , Genotype , Hand, Foot and Mouth Disease/diagnosis , Humans , Japan/epidemiology , Phylogeny , Viral Proteins/genetics
20.
J Med Virol ; 88(7): 1187-93, 2016 Jul.
Article in English | MEDLINE | ID: mdl-26684081

ABSTRACT

Sapovirus (SaV) is a causative agent of gastroenteritis in humans in both sporadic cases and outbreaks. During the period from January 2005 to August 2014, SaV was detected in 30 (5.9%) of 510 gastroenteritis outbreaks in Osaka City, Japan using real-time RT-PCR. Seasonal distribution of SaV-associated outbreaks revealed an increase during the 2011-2012 season and the highest frequency of outbreaks during the 2012-2013 season. Genotyping analysis based on the capsid region demonstrated that the most common genotype was GI.2 (36.7%), in which the strains were closely related. The comparison of complete capsid gene sequences with 18 GI.2 strains (7 strains in this study and 11 from GenBank) between 1990 and 2013 showed that GI.2 strains were classified into at least three genetic clusters (1990-2000, 2004-2007, and 2008-2013) with chronologically unique amino acid residues and accumulation of mutations in the predicted P domain, suggesting the one of the causes of emergence and spread of GI.2 strains. This study will also be helpful for understanding the evolutionary mechanism of the SaV genome.


Subject(s)
Caliciviridae Infections/epidemiology , Disease Outbreaks/statistics & numerical data , Epidemics , Gastroenteritis/epidemiology , Gastroenteritis/virology , Sapovirus/genetics , Adolescent , Adult , Aged , Caliciviridae Infections/virology , Capsid Proteins/genetics , Child , Child, Preschool , Feces/virology , Genome, Viral , Genotype , Humans , Immunologic Surveillance , Infant , Infant, Newborn , Japan/epidemiology , Middle Aged , Mutation , Phylogeny , RNA, Viral/genetics , Seasons , Sequence Analysis, DNA , Young Adult
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