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Katsumi Mizuta,
Chieko Abiko, Yoko Aoki,
Tatsuya Ikeda,
Yoko Matsuzaki,
Seiji Hongo,
Tsutomu Itagaki,
Noriko Katsushima,
Akira Ohmi,
Hidekazu Nishimura,
Tadayuki Ahiko
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ABSTRACT: To clarify the longitudinal molecular epidemiology of coxsackievirus A16, phylogenetic analysis based on the VP1 region of 220 isolates in Yamagata, Japan was performed. The resultant phylogenetic tree indicates that the Yamagata isolates and reference strains can be readily genotyped into three genogroups, and 0, 12 and 208 isolates belonged to the first, second, and third genogroups, respectively. The first genogroup includes only the prototype strain, the second strains that had disappeared by the end of the 20th century and the third comprises those that have been circulating since then in local communities, such as Yamagata.
Microbiology and Immunology 05/2013; 57(5):400-5. · 1.30 Impact Factor
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Katsumi Mizuta,
Chieko Abiko, Yoko Aoki,
Tatsuya Ikeda,
Yoko Matsuzaki,
Seiji Hongo,
Tsutomu Itagaki,
Noriko Katsushima,
Akira Ohmi,
Hidekazu Nishimura,
Tadayuki Ahiko
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[hide abstract]
ABSTRACT: To clarify the longitudinal molecular epidemiology of coxsackievirus A16 (CVA16), phylogenetic analysis based on the VP1 region of 220 isolates in Yamagata, Japan was performed. The phylogenetic tree indicated that the Yamagata isolates and reference strains could be readily genotyped into 3 genogroups, with 0, 12 and 208 isolates belonging to the 1st , 2nd and 3rd genogroup, respectively. The 1st genogroup includes only the prototype strain, the 2nd genogroup consists only of strains that had disappeared by the end of 20th century, and the 3rd genogroup comprises those that have been circulating since then in local communities, such as Yamagata.
Microbiology and Immunology 02/2013; · 1.30 Impact Factor
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Japanese journal of infectious diseases. 01/2013; 66(1):76-8.
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Katsumi Mizuta,
Chieko Abiko, Yoko Aoki,
Tatsuya Ikeda,
Yoko Matsuzaki,
Tsutomu Itagaki,
Fumio Katsushima,
Yuriko Katsushima,
Masahiro Noda,
Hirokazu Kimura,
Tadayuki Ahiko
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ABSTRACT: Most acute respiratory infections (ARIs) are thought to be associated with respiratory viruses that cause similar symptoms. Therefore, assessment of clinical and epidemiologic features of these viruses is important for diagnosing a viral infection. We collected 13,325 nasopharyngeal specimens from patients with ARIs and isolated the virus using a microplate method involving 7 cell lines between 2004 and 2011 in Yamagata, Japan. We isolated a total of 5,483 viruses. Respiratory syncytial virus (RSV), influenza A virus (FluA), human metapneumovirus (hMPV), and human parainfluenza virus type 3 (hPIV3) showed clear yearly seasonal patterns; generally, RSV infections peaked at the end of the year, FluA infections peaked between January and March, hMPV infections peaked between March and April, and hPIV3 showed seasonal outbreaks between May and July. Further, RSV, hMPV, and hPIV3 were commonly isolated in 12.0-13.1% of specimens from children aged less than 4 years, whereas FluA was isolated in 7.3-8.2% of specimens from school-aged children. A generalized view of seasonality and age distribution, particularly on the basis of longitudinal epidemiological data, will be helpful for medical decision-making, including decisions related to the use of rapid test kits, selection of antiviral treatments, restriction of antibiotic therapy, and implementation of infection control strategies.
Japanese journal of infectious diseases. 01/2013; 66(2):140-5.
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Katsumi Mizuta,
Makoto Kuroda,
Masayuki Kurimura,
Yoshikazu Yahata,
Tsuyoshi Sekizuka, Yoko Aoki,
Tatsuya Ikeda,
Chieko Abiko,
Masahiro Noda,
Hirokazu Kimura,
Tetsuya Mizutani,
Takeo Kato,
Toru Kawanami,
Tadayuki Ahiko
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ABSTRACT: Human parechovirus has rarely been shown to cause clinical disease in adults. During June-August 2008, a total of 22 adults sought treatment at Yonezawa City Hospital in Yamagata, Japan, for muscle pain and weakness of all limbs; most also had fever and sore throat. All patients received a clinical diagnosis of epidemic myalgia; clinical laboratory findings suggested an acute inflammatory process. Laboratory confirmation of infection with human parechovirus type 3 (HPeV3) was made for 14 patients; we isolated HPeV3 from 7 patients, detected HPeV3 genome in 11, and observed serologic confirmation of infection in 11. Although HPeV3 is typically associated with disease in young children, our results suggest that this outbreak of myalgia among adults was associated with HPeV3 infection. Clinical consideration should be given to HPeV3 not only in young children but also in adults when an outbreak occurs in the community.
Emerging Infectious Diseases 11/2012; 18(11):1787-93. · 6.79 Impact Factor
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Katsumi Mizuta,
Chieko Abiko, Yoko Aoki,
Tatsuya Ikeda,
Tsutomu Itagaki,
Fumio Katsushima,
Yuriko Katsushima,
Yoko Matsuzaki,
Masahiro Noda,
Hirokazu Kimura,
Tadayuki Ahiko
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ABSTRACT: To clarify the epidemiology of viral acute respiratory infections (ARIs), we isolated 305 human parainfluenza virus type 1 (HPIV1), 154 HPIV2 and 574 HPIV3 strains from 16,962 nasopharyngeal swabs obtained between 2002 and 2011 at pediatric clinics in Yamagata, Japan. The total isolation frequency for HPIV1-3 was 6.1%. Unlike HPIV1 infections, HPIV3 showed clear seasonality with yearly outbreaks in the spring-summer season. HPIV2 tended to appear biannually in autumn-winter. Our results suggested that HPIV1-3 should be considered an important causative agent of ARIs in children, although no reliable technique for the laboratory diagnosis of these infections has been established.
Microbiology and Immunology 09/2012; · 1.30 Impact Factor
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Japanese journal of infectious diseases. 07/2012; 65(4):367-9.
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ABSTRACT: The epidemiological and clinical impacts of influenza C virus infection may have been underestimated by conventional viral culture screening alone.
To evaluate a newly developed real-time polymerase chain reaction (PCR) assay as a tool for diagnosing influenza C virus infection.
The primers and probe for real-time PCR were designed to amplify the conserved region of the nucleoprotein gene based on the aligned sequences of nine isolates from 1967 to 2010. Respiratory specimens from children collected between January 2010 and August 2010 were examined for the presence of influenza C virus by cell culture and real-time PCR. Specimens that were positive for the virus using real-time PCR were further examined using an infectivity assay with embryonated hen's eggs.
Of the 1203 specimens examined, 34 (2.8%) tested positive for the influenza C virus by cell culture and 51 (4.2%) tested positive by real-time PCR. The mean viral load and infectivity titer in specimens that tested positive using cell culture were 3.97×10(8)copies/ml and 5.43×10(5)EID(50)/ml, respectively, and those in specimens that were negative using cell culture were 2.18×10(6)copies/ml and 3.67×10(2)EID(50)/ml, respectively. In the clinical specimens with viral loads less than 10(5)copies/ml, it was not possible to isolate the virus using embryonated hen's eggs. The copy number-to-EID(50) ratio of the clinical specimens was much higher, ranging from 32 to 278,000, than those of culture fluid, ranging from 2.3 to 13.5.
The real-time PCR assay described here can be used as a sensitive method for diagnosing influenza C virus infection.
Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 03/2012; 54(2):130-4. · 3.12 Impact Factor
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Tatsuya Ikeda,
Katsumi Mizuta,
Chieko Abiko, Yoko Aoki,
Tsutomu Itagaki,
Fumio Katsushima,
Yuriko Katsushima,
Yoko Matsuzaki,
Naoko Fuji,
Tadatsugu Imamura,
Hitoshi Oshitani,
Masahiro Noda,
Hirokazu Kimura,
Tadayuki Ahiko
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ABSTRACT: To clarify the epidemiology of enterovirus 68 (EV68), which is one of the most rarely identified enteroviruses, virus isolation and molecular screening using RT-PCR was performed on 6307 respiratory specimens collected at pediatric clinics in Yamagata, Japan between 2005 and 2010. In the years 2005-2009, 10, 1, 2, 0, and 2 (40) EV68-positive cases, respectively, were identified by RT-PCR. In 2010, 40 cases were identified altogether: 2 by isolation only, 26 by RT-PCR only, and 12 by both isolation and RT-PCR. Phylogenetic analysis indicated that plural genetically distinct clusters co-circulated. These results suggest that that difficulty in EV68 isolation leads to an underestimation of the prevalence of EV68 infections.
Microbiology and Immunology 02/2012; 56(2):139-43. · 1.30 Impact Factor
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Katsumi Mizuta,
Mika Saitoh,
Miho Kobayashi,
Hiroyuki Tsukagoshi, Yoko Aoki,
Tatsuya Ikeda,
Chieko Abiko,
Noriko Katsushima,
Tsutomu Itagaki,
Masahiro Noda,
Kunihisa Kozawa,
Tadayuki Ahiko,
Hirokazu Kimura
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ABSTRACT: Human parainfluenza virus type 1 (HPIV1) causes various acute respiratory infections (ARI). Hemagglutinin-neuraminidase (HN) glycoprotein of HPIV1 is a major antigen. However, the molecular epidemiology and genetic characteristics of such ARI are not exactly known. Recent studies suggested that a phylogenetic analysis tool, namely the maximum likelihood (ML) method, may be applied to estimate the evolutionary time scale of various viruses. Thus, we conducted detailed genetic analyses including homology analysis, phylogenetic analysis (using both the neighbor joining (NJ) and ML methods), and analysis of the pairwise distances of HN gene in HPIV1 isolated from patients with ARI in Yamagata prefecture, Japan.
A few substitutions of nucleotides in the second binding site of HN gene were observed among the present isolates. The strains were classified into two major clusters in the phylogenetic tree by the NJ method. Another phylogenetic tree constructed by the ML method showed that the strains diversified in the late 1980s. No positively selected sites were found in the present strains. Moreover, the pairwise distance among the present isolates was relatively short.
The evolution of HN gene in the present HPIV1 isolates was relatively slow. The ML method may be a useful phylogenetic method to estimate the evolutionary time scale of HPIV and other viruses.
Virology Journal 12/2011; 8:533. · 2.34 Impact Factor
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ABSTRACT: Saffold virus (SAFV) is a newly discovered virus belonging to the genus Cardiovirus of the family Picornaviridae. Using molecular techniques, SAFV has been detected, although infrequently, in the stools of both healthy and diarrheic children and in respiratory specimens collected from children with respiratory disease. The epidemiology and pathogenicity of SAFV remain unclear.
Between July 2009 and October 2010, nasopharyngeal specimens were collected from children with acute respiratory infections. The collected samples were used to isolate respiratory viruses, including coxsackievirus, by cell culture and were tested for SAFV by reverse transcription-polymerase chain reaction.
SAFV genotype 2 (SAFV2) was detected in 54 (3.5%) of the 1525 children tested. SAFV2 detections showed an epidemic pattern for a 4-month period with a peak in October 2009. The median age of the SAFV2-positive children was 4 years (range: 7 months-16 years). Among the 35 SAFV2-positive children, excluding cases of viral coinfection, 13 (37.1%) had pharyngitis, 12 (34.3%) had tonsillitis, and 8 (22.8%) had herpangina. Bronchitis and gastroenteritis were detected in 1 case each. Fever (temperature, >38°C) was noted in 33 (94.3%) cases. The median duration of fever was 2 days (range: 1-3 days). Diarrhea was observed in 7 (20.0%) children, but watery and frequent diarrhea was not common. The age distribution and clinical diagnoses associated with SAFV2 infections were similar to those observed with coxsackievirus B4 infections, which detections showed an epidemic pattern during the study period.
SAFV2 is a cause of upper respiratory tract illness that exhibits a pathogenicity similar to that of coxsackievirus B.
The Pediatric Infectious Disease Journal 03/2011; 30(8):680-3. · 3.58 Impact Factor
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Tsutomu Itagaki,
Chieko Abiko,
Tatsuya Ikeda, Yoko Aoki,
Junji Seto,
Katsumi Mizuta,
Tadayuki Ahiko,
Hiroyuki Tsukagoshi,
Manami Nagano,
Masahiro Noda,
Tetsuya Mizutani,
Hirokazu Kimura
Scandinavian Journal of Infectious Diseases 12/2010; 42(11-12):950-2. · 1.72 Impact Factor
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Katsumi Mizuta,
Chieko Abiko, Yoko Aoki,
Tatsuya Ikeda,
Tsutomu Itagaki,
Noriko Katsushima,
Yoko Matsuzaki,
Seiji Hongo,
Masahiro Noda,
Hirokazu Kimura,
Tadayuki Ahiko
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ABSTRACT: To clarify a longitudinal epidemiology,we isolated 280 hMPV strains from patients with acute respiratory infections in Yamagata, Japan, between 2004 and 2009.We observed that the high season for hMPV was from winter to spring (between January and May) and the low season was in the fall (around September and October). A further molecular analysis revealed that subgenogroup A2 (A2) strains were the most commonly isolated (151/280; 53.9%), followed by B2 (108/280; 38.6%) and B1 (19/280; 6.8%). Our results suggested that A2 and B2 have been endemically in circulation as the major types almost every year, whereas other subgenogroups have appeared less frequently.
Microbiology and Immunology 10/2010; 54(10):634-8. · 1.30 Impact Factor
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Yoko Matsuzaki,
Katsumi Mizuta, Yoko Aoki,
Asuka Suto,
Chieko Abiko,
Kanako Sanjoh,
Kanetsu Sugawara,
Emi Takashita,
Tsutomu Itagaki,
Yuriko Katsushima,
Makoto Ujike,
Masatsugu Obuchi,
Takato Odagiri,
Masato Tashiro
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ABSTRACT: Oseltamivir is the preferred antiviral drug for influenza, but oseltamivir-resistant A(H1N1) viruses have circulated worldwide since the 2007-2008 influenza season. We aimed to determine the rate of oseltamivir resistance among A(H1N1) isolates from Yamagata, Japan, to compare the virological characteristics between isolates from the 2007-2008 and 2008-2009 seasons, and to evaluate the clinical effectiveness of oseltamivir.
Oseltamivir resistance, determined by detecting the H275Y mutation in the neuraminidase (NA) gene, was observed in 2.5% (2 of 79) and 100% (77 of 77) of isolates from the 2007-2008 and 2008-2009 seasons, respectively. Antigenic analysis suggested that antigenically different variants of A(H1N1) viruses circulated in the 2008-2009 season. Growth testing demonstrated that the ability of the 2008-2009 isolates to replicate in MDCK cells was similar to those of the oseltamivir-susceptible isolates from the 2007-2008 season. A phylogenetic analysis revealed that two oseltamivir-resistant viruses isolated in the 2007-2008 season were closely related to other oseltamivir-susceptible viruses in Yamagata but were different from oseltamivir-resistant viruses isolated in Europe and North America in the 2007-2008 season. The oseltamivir-resistant viruses isolated in Japan in the 2008-2009 season were phylogenetically similar to oseltamivir-resistant isolates from Europe and North America during the 2007-2008 season. Furthermore, the median duration of fever after the start of oseltamivir treatment was significantly longer in oseltamivir-resistant cases (2 days; range 1-6 days) than in oseltamivir-susceptible cases (1.5 days: range 1-2 days) (P = 0.0356).
Oseltamivir-resistant A(H1N1) isolates from Yamagata in the 2007-2008 season might have acquired resistance through the use of oseltamivir, and the 2008-2009 oseltamivir-resistant isolates might have been introduced into Japan and circulated throughout the country. Influenza surveillance to monitor oseltamivir-resistance would aid clinicians in determining an effective antiviral treatment strategy.
Virology Journal 03/2010; 7:53. · 2.34 Impact Factor
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Japanese journal of infectious diseases. 11/2009; 62(6):481-2.
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Katsumi Mizuta,
Asumi Hirata,
Asuka Suto, Yoko Aoki,
Tadayuki Ahiko,
Tsutomu Itagaki,
Hiroyuki Tsukagoshi,
Yukio Morita,
Masatsugu Obuchi,
Miho Akiyama,
Nobuhiko Okabe,
Masahiro Noda,
Masato Tashiro,
Hirokazu Kimura
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ABSTRACT: We performed phylogenetic and cluster analysis of human rhinovirus species A (HRV-A) isolated from 76 children with acute respiratory infection in Yamagata prefecture, Japan during the period 2003-2007. Phylogenetic trees based on the nucleotide and amino acid sequences of the VP4/VP2 coding region showed that the present strains could be classified into 11 and 8 clusters, respectively. The homology among the present strains ranged from 66.6% to 100% at the nucleotide level and 84.7% to 100% at the amino acid level. The interspecies distance (mean+/-standard deviation) was calculated to be 0.235+/-0.048 at the nucleotide level and 0.076+/-0.033 at the amino acid level. In addition, the phylogenetic trees created based on the nucleotide and amino acid sequences showed that HRV-A strains belonging to some clusters were associated with both upper respiratory infection and wheezy bronchiolitis, while other strains were associated with upper respiratory infection alone. These results suggest that the present HRV-A isolates had a wide nucleotide divergence and were associated with acute respiratory infection, including upper respiratory infection and wheezy bronchiolitis, in Yamagata prefecture, Japan during the investigation period.
Virus Research 11/2009; 147(2):265-74. · 2.94 Impact Factor
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ABSTRACT: The clinical impact of human metapneumovirus (hMPV) genotypes and the relation between the hMPV genotype in circulation and genotype-specific seroprevalence are yet to be clarified. We determined the genotypes of 93 hMPV strains that were isolated between 2004 and 2006 in Yamagata, Japan, and identified 35 genotype A2, 14 genotype B1, and 44 genotype B2 isolates. Children infected with genotype A2 hMPV were significantly older than those infected with genotype B1 hMPV. Diagnosis of laryngitis was more common in children with genotype B1 hMPV infection and wheezing was more prevalent in children with genotype B1 and B2 hMPV infection than in those with genotype A2 hMPV infection. We then examined genotype-specific seroprevalence by neutralization assay. The higher seropositive rate for the B2 genotype among the children aged 1-2 years is likely to reflect the outbreak of B2 genotype strains in the previous year in this community. The low seropositive rate for the B1 genotype among children aged 1-2 years appears to be associated with a finding that more than 70% of children infected with the B1 genotype were less than 3 years old. In conclusion, we found that the different clinical characteristics of hMPV infection may be associated with hMPV genotype, and the predominant genotype during a season and the affecting age may be closely related to genotype-specific immune status within a community.
Journal of Medical Virology 07/2008; 80(6):1084-9. · 2.82 Impact Factor
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ABSTRACT: We have continued the epidemiological study on adenovirus type 7 (Ad7), which re-emerged in 1995 in Yamagata, Japan. Between 1999 and 2004, we isolated only four strains from 10,778 throat swab specimens among children with acute respiratory infections. A serological survey of 303 specimens revealed the antibody-positive rate against Ad7 to be 0-7.4% in children under 10 years of age in 2005, although it was 3.3-16.7% in 1997 and 0% in 1993. Our results suggest that a re-emergence does not always provoke a sudden major outbreak, even if the antibody-positive rate against Ad7 is low in the local community.
Microbiology and Immunology 02/2006; 50(7):553-8. · 1.30 Impact Factor
