-
[show abstract]
[hide abstract]
ABSTRACT: The endotoxin activity assay (EAA) is a FDA-approved blood endotoxin assay that is reported as a useful tool for the diagnosis of gram-negative bacterial infection. However, discrepancies between the results of the EAA and those of the limulus amebocyte lysate (LAL) assay have been reported. Thus, we verified these methods. Blood was incubated with anti-endotoxin antibody, the resultant polymorphonuclear activation to produce oxidants was measured and the EAA level calculated. As a reference endotoxin assay, we used an endotoxin-specific LAL assay. Significant increases in plasma LAL assay levels were observed only in patients with sepsis caused by gram-negative bacterial infections, whereas higher EAA levels were observed in almost all the sepsis cases and the SIRS cases, especially those with acute pancreatitis. Graded amounts of LPS (1-10,000 pg/ml) were spiked into normal blood to obtain dose-response curves: a good dose-response curve, from 1 to 1,000 pg/ml, was obtained for the LAL assay. A good dose-response curve was barely obtained for the EAA; the lowest detection limit seemed to be 1,000 pg/ml. Addition of methylprednisolone decreased the EAA levels. Interleukin-8 (IL-8) induced elevation in EAA levels when IL-8 was added to volunteers' blood samples. Overall, the EAA kit could not measure clinically relevant doses of endotoxin. Because IL-8 induced an increase in EAA level, it is suggested that the EAA level reflects the primed state of polymorphonuclear leukocytes.
Journal of Infection and Chemotherapy 03/2013; · 1.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The clinical effectiveness of the newly released neuraminidase inhibitors (NAIs) laninamivir and peramivir has not been sufficiently evaluated in influenza-infected patients in clinical and practical settings. In this study, we analyzed the clinical data of 211 patients infected with influenza A virus subtype H3N2 (A(H3N2)) and 45 patients infected with influenza A virus subtype H1N1pdm (A(H1N1)pdm09) who received the NAIs oseltamivir, zanamivir, laninamivir, or peramivir during the 2010-2011 influenza season. The duration of fever from the first dose of the NAI to fever alleviation to <37.5 °C was evaluated as an indicator of the clinical effectiveness of the NAIs in the influenza-infected patients. For the A(H3N2)-infected patients, Kaplan-Meier analysis showed the peramivir treatment group had the fastest time of fever alleviation to <37.5 °C (median 17.0 h, 95 % confidence interval [CI] 7.2-26.8 h) of the four treatment groups. No significant difference was found in the time to fever alleviation among the other antivirals, oseltamivir, zanamivir, and laninamivir. Results of multivariate analysis, using a Cox proportional-hazards model (hazard ratio 3.321) adjusted for the factors age, sex, body weight, vaccination status, time from onset to the clinic visit, and body temperature showed significantly faster fever alleviation in the peramivir treatment group compared with the oseltamivir treatment group. For the A(H1N1)pdm09-infected patients, only the oseltamivir and zanamivir treatment groups were compared, and no significant difference in time to alleviation of fever was observed between the two groups. Based on a cycling probe real-time polymerase chain reaction (PCR) assay, none of the A(H1N1)pdm09 strains in this study had the H275Y mutation conferring oseltamivir resistance. Further evaluation of the clinical effectiveness of the newly released NAIs for influenza-infected patients, including those infected with A(H1N1)pdm09, is needed.
Journal of Infection and Chemotherapy 05/2012; · 1.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to investigate the relationship between the blood levels of interleukin (IL)-18 measured in the early stage of acute respiratory failure and the prognosis for patient survival.
The study subjects were 38 patients with acute respiratory failure treated at our institution during the 4-year period from April 2004 to March 2008. The underlying clinical condition was defined as acute respiratory distress syndrome (ARDS; n = 12) or acute lung injury (ALI; n = 26). The serum levels of interleukin (IL)-18, IL-12, and tumor necrosis factor (TNF)-α were measured by enzyme-linked immunosorbent assays.
The ARDS group showed significantly higher serum levels of IL-18, IL-12, and TNF-α even at an early stage after disease onset compared with the ALI group. A negative correlation was noted between the PaO(2)/FIO(2) ratio (P/F ratio) and serum IL-18 level. Analysis of all 38 patients with ALI/ARDS revealed a 30-day mortality rate of 7.9 %, 60-day mortality rate of 15.8 %, and 90-day mortality rate of 18.4 %. The early-stage serum levels of IL-18, IL-12, and TNF-α were significantly higher in the non-survivors at 60 and 90 days, but not at 30 days, than in the corresponding survivors.
The present data demonstrate an inverse correlation between serum IL-18 level and the P/F ratio, suggesting the possible involvement of IL-18 in the pathogenesis of respiratory failure in patients with ALI/ARDS. Early-stage serum IL-18, IL-12, and TNF-α levels appear to reflect the >60-day prognosis in patients with ALI/ARDS.
Journal of Anesthesia 05/2012; 26(5):658-63. · 0.83 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Pandemic influenza A(H1N1) 2009 virus was first detected in Japan in May 2009 and continued to circulate in the 2010-2011 season. This study aims to characterize human influenza viruses circulating in Japan in the pandemic and post-pandemic periods and to determine the prevalence of antiviral-resistant viruses.
Respiratory specimens were collected from patients with influenza-like illness on their first visit at outpatient clinics during the 2009-2010 and 2010-2011 influenza seasons. Cycling probe real-time PCR assays were performed to screen for antiviral-resistant strains. Sequencing and phylogenetic analysis of the HA and NA genes were done to characterize circulating strains.
In the pandemic period (2009-2010), the pandemic influenza A(H1N1) 2009 virus was the only circulating strain isolated. None of the 601 A(H1N1)pdm09 virus isolates had the H275Y substitution in NA (oseltamivir resistance) while 599/601 isolates (99.7%) had the S31N substitution in M2 (amantadine resistance). In the post-pandemic period (2010-2011), cocirculation of different types and subtypes of influenza viruses was observed. Of the 1,278 samples analyzed, 414 (42.6%) were A(H1N1)pdm09, 525 (54.0%) were A(H3N2) and 33 (3.4%) were type-B viruses. Among A(H1N1)pdm09 isolates, 2 (0.5%) were oseltamivir-resistant and all were amantadine-resistant. Among A(H3N2) viruses, 520 (99.0%) were amantadine-resistant. Sequence and phylogenetic analyses of A(H1N1)pdm09 viruses from the post-pandemic period showed further evolution from the pandemic period viruses. For viruses that circulated in 2010-2011, strain predominance varied among prefectures. In Hokkaido, Niigata, Gunma and Nagasaki, A(H3N2) viruses (A/Perth/16/2009-like) were predominant whereas, in Kyoto, Hyogo and Osaka, A(H1N1)pdm09 viruses (A/New_York/10/2009-like) were predominant. Influenza B Victoria(HA)-Yamagata(NA) reassortant viruses (B/Brisbane/60/2008-like) were predominant while a small proportion was in Yamagata lineage. Genetic variants with mutations at antigenic sites were identified in A(H1N1)pdm09, A(H3N2) and type-B viruses in the 2010-2011 season but did not show a change in antigenicity when compared with respective vaccine strains.
PLoS ONE 01/2012; 7(6):e36455. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In June 2009, the World Health Organization announced the 21st century's first influenza pandemic caused by pandemic influenza H1N1 2009 (H1N1 pdm).
Our goal was to analyze antiviral drug resistance and the phylogenetic relationships among hemagglutinin (HA) and neuraminidase (NA) genes of H1N1 pdm samples in Lebanon.
Nasopharyngeal swabs were collected from 197 patients with influenza-like illness from May 2009 through January 2010. Of the 50 influenza A-positive samples, 30 were analyzed for antiviral drug resistance by using in vitro susceptibility assays and cycling-probe real-time PCR. The HA and NA genes were also analyzed.
The results of hemagglutination-inhibition assays confirmed that all 30 analyzed samples were H1N1 pdm. In July 2009, community transmission of H1N1 pdm was detected in Lebanon, and an outbreak occurred in October 2009. The outbreak cases were caused by a strain with 4 mutations in the NA gene (i.e., V42I, N68T, N248D, and E462K) and 2 mutations in the HA gene: 1 in the Ca1 antigenic site (i.e., S206T) and 1 in the Ca2 antigenic site (i.e., D225E). This strain was closely related to a major H1N1 pdm cluster that was isolated worldwide. All 30 samples were amantadine-resistant, and none were zanamivir-resistant. The 1 oseltamivir-resistant sample appeared to be from a community-transmitted case in an otherwise healthy 2-year-old child.
Continuous monitoring of oseltamivir susceptibility among H1N1 pdm is essential to guide the effective use of this drug.
Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 07/2011; 51(3):170-4. · 3.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The objective of this study was to characterize the off-seasonal influenza virus A subtype H3N2, which caused an outbreak in an elderly hospital in Niigata, Japan. Virus isolates were subtyped by the hemagglutination-inhibition test and screened for antiviral drug sensitivity by real-time PCR using cycling probe technology the and 50% inhibitory concentration (IC(50)) method. Whole genome sequencing was performed in order to determine the phylogeny of the outbreak virus. Seven virus isolates were analyzed in this study, and the results showed that all belonged to the influenza virus A (H3N2). These viruses exhibited the S31N mutation in M2, which confers resistance to amantadine. The results of the IC(50) analysis showed that these viruses were sensitive to both oseltamivir and zanamivir. Whole genome analysis revealed that the virus was similar to the A/Perth/16/2009 strain and that it is a triple reassortant virus with a 3+3+2 pattern of segment recombination.
Japanese journal of infectious diseases. 05/2011; 64(3):237-41.
-
Taeko Oguma,
Reiko Saito,
Hironori Masaki,
Kazuhiko Hoshino,
Hassan Zaraket, Yasushi Suzuki,
Isolde Caperig-Dapat,
Clyde Dapat,
Tatiana Baranovich,
Reiki Kuroki,
Yasushi Makimoto,
Yutaka Shirahige,
Norichika Asoh,
Satoshi Degawa,
Hidefumi Ishikawa,
Hironobu Kageura,
Maki Hosoi,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: To describe outbreaks of nosocomial influenza infection with molecular methods and to elucidate the viral linkages among outbreak case patients including both inpatients and healthcare workers (HCWs).
A 180-bed acute and long-term care hospital in Japan.
Retrospective observational study of nosocomial outbreaks of infection with influenza A/H3N2. Together with information about onset dates and vaccination history, we obtained nasopharyngeal swab samples from individuals with cases of influenza or influenza-like illness (ILI). The hemagglutinin genes of the recovered viruses were sequenced and compared, along with those of community-circulating strains, for similarity by phylogenetic tree analysis.
The outbreaks occurred from February 26 through April 3, 2007, during the 2006-2007 epidemic season, and they involved 11 patients and 13 HCWs. The 2 outbreaks involved 2 different genotypes of influenza A/H3N2 viruses. These virus variants were closely related to the influenza strains that were circulating in the community during the same epidemic season.
This study showed the dissemination of highly homologous influenza virus variants among inpatients and HCWs within a short period, as a result of nosocomial transmission. These strains were also similar to influenza strains that were circulating in the community.
Infection Control and Hospital Epidemiology 03/2011; 32(3):267-75. · 3.67 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In eight successive seasons (2001 to 2009), a total of 726 human respiratory syncytial virus (HRSV) infections from a total of 1,560 children with acute lower respiratory tract illness were identified. Molecular analysis of the attachment (G) protein gene confirmed that 52 (7.8%) children were infected more than once with any of the 3 genotypes of HRSV-A (genotypes GA5, NA1, and NA2) and/or 6 genotypes of HRSV-B (genotypes BA4, BA5, and BA7 to BA10). Repeated infections in 46 cases (82.1%) occurred in the next season, and only one case occurred in the same season (10-day interval). First infections were 33 (63.5%) HRSV-A cases and 19 (36.5%) HRSV-B cases, whereas second infections occurred in 35 (67.3%) HRSV-A cases and 17 (32.7%) HRSV-B cases. Third infections were attributed to 4 (100.0%) HRSV-A cases. Homologous subgroup reinfections were detected in 28 cases, 23 HRSV-A cases and 5 HRSV-B cases (P = 0.005), whereas homologous genotype reinfections were detected only for 5 HRSV-A cases (2GA5 and 3NA2) but not any HRSV-B case. Heterologous subgroup reinfections were detected in 28 cases, 12 cases from HRSV-A-to-HRSV-B reinfections and 16 cases from HRSV-B-to-HRSV-A reinfections. Genotypes NA1 and NA2 had higher numbers of heterologous genotype infections than did other genotypes. Our observations suggest that repeated infections occur more frequently in HRSV-A strains than in HRSV-B strains, and heterologous genotype reinfections occur more frequently than homologous genotype reinfections, especially in the case of the emerging genotypes NA1 and NA2 of HRSV-A strains that circulated in the community during our study period.
Journal of clinical microbiology 12/2010; 49(3):1034-40. · 4.16 Impact Factor
-
Yasushi Suzuki,
Reiko Saito,
Isamu Sato,
Hassan Zaraket,
Makoto Nishikawa,
Tsutomu Tamura,
Clyde Dapat,
Isolde Caperig-Dapat,
Tatiana Baranovich,
Takako Suzuki,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: Neuraminidase inhibitors are agents used against influenza viruses; however, the emergence of drug-resistant strains is a major concern. Recently, the prevalence of oseltamivir-resistant seasonal influenza A (H1N1) virus increased globally and the emergence of oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses was reported. In this study, we developed a cycling probe real-time PCR method for the detection of oseltamivir-resistant seasonal influenza A (H1N1) and pandemic influenza A (H1N1) 2009 viruses. We designed two sets of primers and probes that were labeled with 6-carboxyfluorescein or 6-carboxy-X-rhodamine to identify single nucleotide polymorphisms (SNPs) that correspond to a histidine and a tyrosine at position 275 in the neuraminidase protein, respectively. These SNPs confer susceptibility and resistance to oseltamivir, respectively. In the 2007-2008 season, the prevalence of oseltamivir-resistant H1N1 viruses was 0% (0/72), but in the 2008-2009 season, it increased to 100% (282/282). In the 2009-2010 season, all of the pandemic influenza A (H1N1) 2009 viruses were susceptible to oseltamivir (0/73, 0%). This method is sensitive and specific for the screening of oseltamivir-resistant influenza A (H1N1) viruses. This method is applicable to routine laboratory-based monitoring of drug resistance and patient management during antiviral therapy.
Journal of clinical microbiology 11/2010; 49(1):125-30. · 4.16 Impact Factor
-
Isolde C Dapat,
Yugo Shobugawa,
Yasuko Sano,
Reiko Saito,
Asami Sasaki, Yasushi Suzuki,
Akihiko Kumaki,
Hassan Zaraket,
Clyde Dapat,
Taeko Oguma,
Masahiro Yamaguchi,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: Phylogenetic analysis of respiratory syncytial virus (RSV) group B genotype BA strains from the 2002-2003 to 2009-2010 seasons collected in Niigata, Japan, revealed four distinct clusters, designated new BA genotypes BA7, BA8, BA9, and BA10. These new genotypes were not associated with large outbreaks in the community.
Journal of clinical microbiology 09/2010; 48(9):3423-7. · 4.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A 64-year-old man took levofloxacin 100 mg three times a day from the day before trans-rectal prostate needle biopsy. He suddenly fell into septic shock about 12 hours after the biopsy. We performed polymyxin B-immobilized fiber-direct hemoperfusion treatment at our intensive care unit. The circle dynamics was stable after five days of observation, and he was discharged seven days after the event. Levofloxacin-resistant Escherichia coli (E. coli) was detected by blood and urine culture.
Hinyokika kiyo. Acta urologica Japonica 08/2010; 56(8):453-6.
-
Hassan Zaraket,
Reiko Saito,
Rima Wakim,
Carelle Tabet,
Fouad Medlej,
Mariam Reda,
Tatiana Baranovich, Yasushi Suzuki,
Clyde Dapat,
Isolde Caperig-Dapat,
Ghassan S Dbaibo,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: The emergence of antiviral drug-resistant strains of the influenza virus in addition to the rapid spread of the recent pandemic A(H1N1) 2009 virus highlight the importance of surveillance of influenza in identifying new variants as they appear. In this study, genetic characteristics and antiviral susceptibility patterns of influenza samples collected in Lebanon during the 2008-09 season were investigated. Forty influenza virus samples were isolated from 89 nasopharyngeal swabs obtained from patients with influenza-like illness. Of these samples, 33 (82.5%) were A(H3N2), 3 (7.5%) were A(H1N1), and 4 (10%) were B. All the H3N2 viruses were resistant to amantadine but were sensitive to oseltamivir and zanamivir; while all the H1N1 viruses were resistant to oseltamivir (possessed H275Y mutation, N1 numbering, in their NA) but were sensitive to amantadine and zanamivir. In the case of influenza B, both Victoria and Yamagata lineages were identified (three and one isolates each, respectively) and they showed decreased susceptibility to oseltamivir and zanamivir when compared to influenza A viruses. Influenza circulation patterns in Lebanon were very similar to those in Europe during the same season. Continued surveillance is important to fully elucidate influenza patterns in Lebanon and the Middle East in general, especially in light of the current influenza pandemic.
Journal of Medical Virology 07/2010; 82(7):1224-8. · 2.82 Impact Factor
-
Reiko Saito,
Isamu Sato, Yasushi Suzuki,
Tatiana Baranovich,
Ryu Matsuda,
Nobuo Ishitani,
Clyde Dapat,
Isolde Caperig Dapat,
Hassan Zaraket,
Taeko Oguma,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: Little is known about whether neuraminidase inhibitors are effective for children infected with oseltamivir-resistant influenza A(H1N1) viruses.
Children aged 15 years and younger having influenza-like illness and who visited outpatient clinics within 48 hours of fever onset were enrolled from 2006-2007 to 2008-2009 influenza seasons in Japan. Patients received oseltamivir, zanamivir, or no treatment after screening by a rapid antigen test. Nasopharyngeal swabs were collected before antiviral therapy and were used for virus isolation. Oseltamivir resistance was determined by detection of the H275Y mutation in neuraminidase, and susceptibility test using neuraminidase inhibition assay. Daily body temperature was evaluated according to drug type and susceptibility by univariate and multivariate analyses.
Of 1647 patients screened, 238 oseltamivir-resistant H1N1 cases (87 oseltamivir-treated, 64 zanamivir-treated, and 87 nontreated) and 110 oseltamivir-susceptible cases (60 oseltamivir-treated and 50 nontreated) were evaluated. In oseltamivir-resistant cases, fever on days 4 to 5 after the start of treatment was significantly higher in oseltamivir-treated and nontreated than in zanamivir-treated patients (P < 0.05). In oseltamivir-susceptible cases, fever was significantly lower in oseltamivir-treated than nontreated on days 3 to 6 (P < 0.01). Similar findings were obtained for duration of the fever and proportion of recurrent fever. Reduced effectiveness of oseltamivir was more prominent in children 0 to 6 years old than in those 7 to 15 years old. Multiple logistic regression analysis showed that lower age, nontreatment, and oseltamivir treatment of oseltamivir-resistant patients were factors associated with the duration of the longer fever.
Infection with oseltamivir-resistant viruses significantly reduced the effectiveness of oseltamivir, and this tendency was more apparent in younger children.
The Pediatric Infectious Disease Journal 05/2010; 29(10):898-904. · 3.58 Impact Factor
-
Gaku Takahashi,
Nobuhiro Sato,
Yasunori Yaegashi,
Masahiro Kojika,
Naoya Matsumoto,
Tomohiro Kikkawa,
Tatsuyori Shozushima,
Shinji Akitomi,
Kiichi Aoki,
Naoko Ito,
Koichi Hoshikawa, Yasushi Suzuki,
Yoshihiro Inoue,
Go Wakabayashi,
Shigeatsu Endo
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to assess lipopolysaccharide (LPS)-stimulated cytokine production in the presence of linezolid (LZD) in comparison with the drug effect on the plasma endotoxin level. Peripheral venous whole-blood samples collected from five healthy subjects were stimulated with 10 microg/ml of LPS. LZD was then added to the LPS-stimulated blood samples at concentrations of 0, 2, 4, and 15 microg/ml , followed by incubation for 24 h at 37 degrees C in a 5% CO(2)-95% air atmosphere. Supernatants of the resultant cultures were assayed to determine the levels of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-10, monocyte chemoattractant protein (MCP)-1, and endotoxin. Significant decreases in the levels of TNF-alpha and IFN-gamma were observed in the LZD 2, 4, and 15 microg/ml groups as compared with that in the 0 microg/ml group (Dunnett's procedure; P < 0.05). The level of IL-10 tended to increase irrespective of the LZD concentration; however, no significant intergroup differences were observed [analysis of variance (ANOVA); P = 0.68]. No significant decrease of the endotoxin level was observed in the LZD 2, 4, or 15 microg/ml groups as compared with that in the 0 microg/ml group, with no significant intergroup differences (ANOVA; P = 0.83). No change in the MCP-1 levels was observed irrespective of the LZD concentration (ANOVA; P = 0.82). To conclude: (1) it appears possible that LZD inhibits the production of INF-gamma and TNF-alpha to a limited extent; (2) LZD did not exert any inhibitory effect on endotoxin production by bacteria, while suppressing cytokine production. The results indicate that LZD may have a significant role in saving the lives of patients with sepsis.
Journal of Infection and Chemotherapy 04/2010; 16(2):94-9. · 1.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The emergence and widespread occurrence of antiviral drug-resistant seasonal human influenza A viruses, especially oseltamivir-resistant A/H1N1 virus, are major concerns. To understand the genetic background of antiviral drug-resistant A/H1N1 viruses, we performed full genome sequencing of prepandemic A/H1N1 strains. Seasonal influenza A/H1N1 viruses, including antiviral-susceptible viruses, amantadine-resistant viruses, and oseltamivir-resistant viruses, obtained from several areas in Japan during the 2007-2008 and 2008-2009 influenza seasons were analyzed. Sequencing of the full genomes of these viruses was performed, and the phylogenetic relationships among the sequences of each individual genome segment were inferred. Reference genome sequences from the Influenza Virus Resource database were included to determine the closest ancestor for each segment. Phylogenetic analysis revealed that the oseltamivir-resistant strain evolved from a reassortant oseltamivir-susceptible strain (clade 2B) which circulated in the 2007-2008 season by acquiring the H275Y resistance-conferring mutation in the NA gene. The oseltamivir-resistant lineage (corresponding to the Northern European resistant lineage) represented 100% of the H1N1 isolates from the 2008-2009 season and further acquired at least one mutation in each of the polymerase basic protein 2 (PB2), polymerase basic protein 1 (PB1), hemagglutinin (HA), and neuraminidase (NA) genes. Therefore, a reassortment event involving two distinct oseltamivir-susceptible lineages, followed by the H275Y substitution in the NA gene and other mutations elsewhere in the genome, contributed to the emergence of the oseltamivir-resistant lineage. In contrast, amantadine-resistant viruses from the 2007-2008 season distinctly clustered in clade 2C and were characterized by extensive amino acid substitutions across their genomes, suggesting that a fitness gap among its genetic components might have driven these mutations to maintain it in the population.
Journal of clinical microbiology 04/2010; 48(4):1085-92. · 4.16 Impact Factor
-
Clyde Dapat, Yasushi Suzuki,
Reiko Saito,
Yadanar Kyaw,
Yi Yi Myint,
Nay Lin,
Htun Naing Oo,
Khin Yi Oo,
Ne Win,
Makoto Naito,
Go Hasegawa,
Isolde C Dapat,
Hassan Zaraket,
Tatiana Baranovich,
Makoto Nishikawa,
Takehiko Saito,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: In 2007 and 2008 in Myanmar, we detected influenza viruses A (H3N2) that exhibited reduced sensitivity to both zanamivir and amantadine. These rare and naturally occurring viruses harbored a novel Q136K mutation in neuraminidase and S31N mutation in M2.
Emerging Infectious Diseases 03/2010; 16(3):493-6. · 6.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The prevalence of amantadine-resistant influenza A/H3N2 viruses (belonging to the N-lineage), possessing an S31N mutation in the M2 protein and S193F and D225N substitutions in their HA1 subunit, has significantly increased worldwide since 2005. The aim of this study was to clarify the genomic events contributing to the evolution and continuity of the N-lineage amantadine-resistant viruses.
The full genome sequence of A/H3N2 isolates, including both amantadine-resistant and amantadine-sensitive viruses, collected in Japan between 2006 and 2008, was determined and phylogenetically compared with isolates obtained from the database.
On the basis of the full genome sequence analysis, the N-lineage could be further divided into three genetically related clades: N1 (A/Wisconsin/67/2005-like amantadine-resistant viruses from years 2005-2007), N2 (amantadine-sensitive viruses from 2007) and N3 (A/Brisbane/10/2007-like amantadine-resistant viruses from 2007 and 2008). The 2006/2007 season showed cocirculation of antigenic variants of amantadine-resistant viruses of clades N1 and N3 in addition to the N2-sensitive viruses. In the 2007/2008 season, the clade N3 amantadine-resistant lineage dominated and replaced other strains. Phylogenetic analysis of each individual segment suggested that N2 and N3 were generated from two independent reassortment events involving clade N1 viruses and pre-N-lineage strains.
Our data show that several reassortment events have contributed to the evolution of amantadine-resistant A/H3N2 strains and, consequently, to the successful spread of this lineage. Although amantadine resistance is caused by single amino acid mutations in the M2 protein, genome-wide adjustment involving multiple genes appears to be necessary to obtain efficient replication and transmission of resistant viruses. Such adjustments are attainable through reassortment of segments among different virus lineages.
Antiviral therapy 01/2010; 15(3):307-19. · 3.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A substantial increase in oseltamivir-resistant A(H1N1) influenza viruses was reported in Europe in late 2007.
To monitor the antiviral susceptibility profile of human A(H1N1) influenza viruses in Japan during the 2007-2008 and 2008-2009 seasons.
Viruses were obtained from respiratory samples of patients with influenza collected in Japan between December 2007 and April 2008 (n=1046) and between December 2008 and April 2009 (n=1789). Oseltamivir resistance was determined by an H274Y-specific real-time PCR cycling probe assay and a neuraminidase inhibition assay. Amantadine resistance was assessed by sequencing the M2 gene. Sequencing of the hemagglutinin and NA genes was performed to infer phylogenetic relationships between different strains.
Three of 687 (0.4%) A(H1N1) viruses from the 2007-2008 season and 745 of 745 (100%) viruses from the 2008-2009 season carried the NA-H274Y substitution and demonstrated a >300-fold reduction in oseltamivir susceptibility. All oseltamivir-resistant viruses from the 2008-2009 season possessed an A193T substitution in the receptor-binding domain of the hemagglutinin. Amantadine resistance was detected in 431 of 687 (62.7%) and 0 of 745 (0.0%) of the A(H1N1) viruses from the 2007-2008 and 2008-2009 seasons, respectively.
A dramatic surge in oseltamivir-resistant A(H1N1) viruses possessing the NA-H274Y substitution was detected in Japan during the 2008-2009 season. The emergence of oseltamivir-resistant viruses was facilitated by mutations in the viral genome. Intensified surveillance, including phenotypic assays and sequencing of the hemagglutinin, neuraminidase, and M2 gene would allow monitoring of the spread and evolution of drug-resistant influenza virus variants.
Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 12/2009; 47(1):23-8. · 3.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Amantadine is one of the antiviral agents used to treat influenza A virus infections, but resistant strains have widely emerged worldwide. In the present study, we developed a novel method to detect amantadine-resistant strains harboring the Ser31Asn mutation in the M2 gene based on the cycling probe method and real-time PCR. We also studied the rate of amantadine resistance in the 2007-2008 influenza season in Japan. Two different primer and cycling probe sets were designed for A/H1N1 and A/H3N2 each to detect a single nucleotide polymorphism corresponding to Ser/Asn at residue 31 of the M2 protein. By using nasopharyngeal swabs from patients with influenza-like and other respiratory illnesses and virus isolates, the specificity and the sensitivity of the cycling probe method were evaluated. High frequencies of amantadine resistance were detected among the A/H1N1 (411/663, 62%) and A/H3N2 (56/56, 100%) virus isolates collected from six prefectures in Japan in the 2007-2008 influenza season. We confirmed that the cycling probe method is suitable for the screening of both nasopharyngeal swabs and influenza virus isolates for amantadine-resistant strains and showed that the incidence of amantadine resistance among both A/H1N1 and A/H3N2 viruses remained high in Japan during the 2007-2008 season.
Journal of clinical microbiology 11/2009; 48(1):57-63. · 4.16 Impact Factor
-
Clyde Dapat,
Reiko Saito,
Yadanar Kyaw,
Makoto Naito,
Go Hasegawa, Yasushi Suzuki,
Isolde C Dapat,
Hassan Zaraket,
Tin Maung Cho,
Danjuan Li,
Taeko Oguma,
Tatiana Baranovich,
Hiroshi Suzuki
[show abstract]
[hide abstract]
ABSTRACT: To perform genetic analysis of influenza A and B viruses in Myanmar from 2005 to 2007 and to determine the prevalence of amantadine-resistant influenza A viruses.
Phylogenies of the HA and NA genes were analyzed and mutations in M2 that confer resistance to amantadine were screened.
Influenza in Myanmar exhibited seasonality, which coincided during the rainy season from June to August. Out of 2,618 samples, 76 influenza A and 132 influenza B viruses were isolated. Phylogenetic analysis showed that in 2005, 11 A/H1N1 isolates formed one cluster with A/Solomon Islands/3/2006 and were amantadine-sensitive strains. One A/H3N2 isolate was amantadine-resistant harboring S31N mutation in M2 and possessing S193F and D225N substitutions in HA (clade N), similar to A/Wisconsin/67/2005. No viruses were isolated in 2006 due to sample storage failure. In 2007, all 64 A/H3N2 isolates were amantadine-resistant and similar to A/Brisbane/10/2007. For influenza B, 3 Yamagata-lineage and 17 Victoria-lineage isolates were detected in 2005 and 112 Victoria-lineage viruses were isolated in 2007. All Victoria-lineage isolates were reassortants possessing NA derived from the Yamagata lineage.
Continuous surveillance in tropical countries is important for elucidating the seasonality of influenza and determining the molecular characteristics of circulating strains.
Intervirology 09/2009; 52(6):310-20. · 2.34 Impact Factor
