Publications (10)29.53 Total impact
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Article: Antigenic variation of H1N1, H1N2 and H3N2 swine influenza viruses in Japan and Vietnam.
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ABSTRACT: The antigenicity of the influenza A virus hemagglutinin is responsible for vaccine efficacy in protecting pigs against swine influenza virus (SIV) infection. However, the antigenicity of SIV strains currently circulating in Japan and Vietnam has not been well characterized. We examined the antigenicity of classical H1 SIVs, pandemic A(H1N1)2009 (A(H1N1)pdm09) viruses, and seasonal human-lineage SIVs isolated in Japan and Vietnam. A hemagglutination inhibition (HI) assay was used to determine antigenic differences that differentiate the recent Japanese H1N2 and H3N2 SIVs from the H1N1 and H3N2 domestic vaccine strains. Minor antigenic variation between pig A(H1N1)pdm09 viruses was evident by HI assay using 13 mAbs raised against homologous virus. A Vietnamese H1N2 SIV, whose H1 gene originated from a human strain in the mid-2000s, reacted poorly with post-infection ferret serum against human vaccine strains from 2000-2010. These results provide useful information for selection of optimal strains for SIV vaccine production.Archives of Virology 02/2013; · 2.11 Impact Factor -
Article: Isolation of the Pandemic (H1N1) 2009 virus and its reassortant with an H3N2 swine influenza virus from healthy weaning pigs in Thailand in 2011.
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ABSTRACT: A total of 300 nasal swabs were collected from 5 pig farms in two provinces in the Eastern part of Thailand in February 2011 and were subjected to viral isolation of influenza A viruses. Two H3N2 and 6 H1N1 influenza A viruses were isolated from swabs collected from clinically healthy weaning pigs on farms in Chonburi and Chachoengsao provinces, respectively. The H3N2 isolates consisted of the hemagglutinin (HA) and neuraminidase (NA) genes closely related to Thai SIVs and derived from a cluster of human seasonal H3N2 strains circulating around 1996-1997. The remaining gene segments of the isolates originated from the Pandemic (H1N1) 2009 (A (H1N1) pdm09) virus. Antigenicity of the H3N2 isolates was distinguishable from a human seasonal vaccine strain in the 1996-1998 seasons that represented antigenicity of the seasonal strains around 1996-1998. Nasal swabs from a Chachoengsao farm yielded A (H1N1) pdm09 viruses in chicken embryonated eggs and MDCK cells. A (H1N1) pdm09 viruses isolated in this study grew poorly in MDCK cells. Deduced amino acid sequences of the HA1 region of the HA protein of egg isolated viruses were identical to the sequences directly amplified from original swab samples. Our result demonstrated that the A (H1N1) pdm09 virus has been established in the Thai pig population and this has resulted in genetic reassortment with Thai SIV that previously circulated among pigs.Virus Research 08/2012; 169(1):175-81. · 2.94 Impact Factor -
Article: Identification of host genes linked with the survivability of chickens infected with recombinant viruses possessing H5N1 surface antigens from a highly pathogenic avian influenza virus.
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ABSTRACT: Seventeen recombinant viruses were generated by a reverse genetic technique to elucidate the pathogenicity of highly pathogenic avian influenza viruses (HPAIVs) in chickens. The recombinant viruses generated possessed hemagglutinin (HA) and neuraminidase (NA) genes from an HPAIV. Other segments were combinations of the genes from an HPAIV and two low-pathogenic avian influenza viruses (LPAIVs) derived from chicken (LP) and wild bird (WB). Exchange of whole internal genes from an HPAIV with those of an LPAIV resulted in a significant extension of the survival time following intranasal infection of the chickens with the recombinants. Survival analysis demonstrated that the exchange of a gene segment affected survivability of the chickens with statistical significance. The analysis revealed three groups of recombinants with various gene constellations that depended upon the survivability of the infected chickens. Recombinants where the PA gene was exchanged from LP to WB in the LP gene background, LP (W/PA), did not kill any chickens. LP (W/PA) replicated less efficiently both in vitro and in vivo, suggesting that the intrinsic replication ability of LP (W/PA) affects pathogenicity; however, such a correlation was not seen for the other recombinants. Microarray analysis of the infected chicken lungs indicated that the expression of 7 genes, CD274, RNF19B, OASL, ZC3HAV1 [corrected] , PLA2G6, GCH1, and USP18, correlated with the survivability of the chickens infected (P < 0.01). Further analysis of the functions of these genes in chickens would aid in the understanding of host gene responses following fatal infections by HPAIVs.Journal of Virology 12/2011; 86(5):2686-95. · 5.40 Impact Factor -
Article: Swine influenza virus infection in different age groups of pigs in farrow-to-finish farms in Thailand.
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ABSTRACT: Understanding swine influenza virus (SIV) ecology has become more and more important from both the pig industry and public health points of views. However, the mechanism whereby SIV occurs in pig farms is not well understood. The purpose of this study was to develop a proper strategy for SIV surveillance. We conducted longitudinal monitoring in 6 farrow-to-finish farms in the central region of Thailand from 2008 to 2009. Nasal swabs and serum samples were collected periodically from clinically healthy pigs consisting of sows, fattening pigs, weaned piglets and pigs transferred from other farms. A total of 731 nasal swabs were subjected to virus isolation and 641 serum samples were subjected to detection of SIV antibodies against H1 and H3 subtypes using the hemagglutination inhibition test and ELISA. Twelve SIVs were isolated in this study and eleven were from piglets aged 4 and 8 weeks. Phylogenetical analysis revealed that SIVs isolated from different farms shared a common ancestor. Antibodies against SIVs were detected in fattening pigs on farms with no SIV isolation in the respective periods studied. These observations suggested that piglets aged 8 weeks or younger could be a main target for SIV isolation. Farm-to-farm transmission was suggested for farms where pigs from other farms are introduced periodically. In addition, antibodies against SIVs detected in fattening pigs could be a marker for SIV infection in a farm. The present study provided important information on SIV surveillance that will enable better understanding of SIV ecology in farrow-to-finish farms.Virology Journal 12/2011; 8:537. · 2.34 Impact Factor -
Article: Host cytokine responses of pigeons infected with highly pathogenic Thai avian influenza viruses of subtype H5N1 isolated from wild birds.
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ABSTRACT: Highly pathogenic avian influenza virus (HPAIV) of the H5N1 subtype has been reported to infect pigeons asymptomatically or induce mild symptoms. However, host immune responses of pigeons inoculated with HPAIVs have not been well documented. To assess host responses of pigeons against HPAIV infection, we compared lethality, viral distribution and mRNA expression of immune related genes of pigeons infected with two HPAIVs (A/Pigeon/Thailand/VSMU-7-NPT/2004; Pigeon04 and A/Tree sparrow/Ratchaburi/VSMU-16-RBR/2005; T.sparrow05) isolated from wild birds in Thailand. The survival experiment showed that 25% of pigeons died within 2 weeks after the inoculation of two HPAIVs or medium only, suggesting that these viruses did not cause lethal infection in pigeons. Pigeon04 replicated in the lungs more efficiently than T.sparrow05 and spread to multiple extrapulmonary organs such as the brain, spleen, liver, kidney and rectum on days 2, 5 and 9 post infection. No severe lesion was observed in the lungs infected with Pigeon04 as well as T.sparrow05 throughout the collection periods. Encephalitis was occasionally observed in Pigeon04- or T.sparrow05-infected brain, the severity, however was mostly mild. To analyze the expression of immune-related genes in the infected pigeons, we established a quantitative real-time PCR analysis for 14 genes of pigeons. On day 2 post infection, Pigeon04 induced mRNA expression of Mx1, PKR and OAS to a greater extent than T.sparrow05 in the lungs, however their expressions were not up-regulated concomitantly on day 5 post infection when the peak viral replication was observed. Expressions of TLR3, IFNα, IL6, IL8 and CCL5 in the lungs following infection with the two HPAIVs were low. In sum, Pigeon04 exhibited efficient replication in the lungs compared to T.sparrow05, but did not induce excessive host cytokine expressions. Our study has provided the first insight into host immune responses of pigeons against HPAIV infection.PLoS ONE 01/2011; 6(8):e23103. · 4.09 Impact Factor -
Article: Differential host gene responses in mice infected with two highly pathogenic avian influenza viruses of subtype H5N1 isolated from wild birds in Thailand.
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ABSTRACT: In Thailand, highly pathogenic avian influenza (HPAI) viruses of subtype H5N1 had been isolated from various wild birds during the HPAI outbreak in poultries. In this study, we examined the pathogenicity of two wild bird isolates (A/Pigeon/Thailand/VSMU-7-NPT/2004; Pigeon04 and A/Tree sparrow/Ratchaburi/VSMU-16-RBR/2005; T.sparrow05) in mice. They showed similar replication in several organs and lethal outcome. However, on day 3 post-infection, Pigeon04 induced mRNA expression of proinflammatory cytokines (IL6 and TNFα) and MIP-2, neutrophil chemoattractant, in the lungs, resulting in severe pneumonia that was accompanied by neutrophil infiltration. In contrast, on day 7 post-infection, T.sparrow05 induced the expression of several cytokines to a greater extent than Pigeon04; it also potently induced mRNA expression of several cytokines in brains of the infected mice that triggered frequent inflammatory events. In sum, our study demonstrated that two HPAI viruses induced different host responses, despite having similar replications, resulting in lethal outcome in mice.Virology 01/2011; 412(1):9-18. · 3.35 Impact Factor -
Article: Real-time reverse transcription-PCR assay for differentiating the Pandemic H1N1 2009 influenza virus from swine influenza viruses.
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ABSTRACT: Since the Pandemic H1N1 2009 (H1N1pdm) influenza virus emerged in human in 2009, H1N1pdm, classical swine H1, Eurasian avian-like H1, human-like H1 and human-like H3 swine influenza viruses have circulated in pig populations, and avian H9N2 viruses have been isolated in pigs as well. In this study, TaqMan single-step real-time reverse transcription-PCR (rtRT-PCR) assays targeting the hemagglutinin gene were developed to differentiate H1N1pdm from other genetic lineages of the H1 subtype and other subtypes of influenza viruses circulating in human and pig populations for veterinary use. H1N1pdm rtRT-PCR detected H1N1pdm RNA and did not cross-react with classical swine H1, Eurasian avian-like H1, human-like H1, human-like H3 swine and avian H9 influenza viruses RNA. Classical swine H1, Eurasian avian-like H1, human-like H1 and H3 and avian H9 rtRT-PCR were reacted exclusively with viral RNA of their respective lineages and subtypes. The results demonstrate that these assays are useful for the diagnosis of the H1N1pdm virus in both human- and animal-health-related fields.Journal of virological methods 12/2010; 170(1-2):169-72. · 2.13 Impact Factor -
Article: Occurrence of a pig respiratory disease associated with swine influenza A (H1N2) virus in Tochigi Prefecture, Japan.
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ABSTRACT: In February 2008, a feeder pig herd of the affected farm in Tochigi Prefecture, Japan, showed increasing respiratory symptoms; by April, the situation worsened with 12-16 pigs dying daily. Diagnostic tests revealed the presence of H1N2 subtype of swine influenza virus (SIV) and Pasteurella multocida from nasal swab and lung emulsion. Serological tests by hemagglutination inhibition method and enzyme-linked immunosorbent assay method (ELISA; imported from U.S.A.) indicated the spread of SIV into the pig herds of the affected farm around April 2008. The severe infection and subsequent damage were considered as a result of the combined infection of SIV (H1N2) and bacteria that may have been prevalent in the pig farm. Genetic homology search of sequences for the hemagglutinin (HA) and neuraminidase (NA) genes of A/swine/Tochigi/1/08 showed high homology to Japanese SIVs (H1N2) isolated in the 2000s. Therefore, we considered that Japanese SIV (H1N2) has established an independent stable lineage and participated in infecting pig populations as one of the factors of the pig respiratory disease complex. Consistent surveillance would contribute to clarifying the prevalence of dominant SIVs.Journal of Veterinary Medical Science 04/2010; 72(4):481-8. · 0.85 Impact Factor -
Article: Alterations in receptor-binding properties of swine influenza viruses of the H1 subtype after isolation in embryonated chicken eggs.
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ABSTRACT: Alterations of the receptor-binding properties of swine influenza A viruses (SIVs) during their isolation in embryonated chicken eggs have not been well studied. In this study, the receptor-binding properties of classical H1 SIVs isolated solely in eggs or Madin-Darby canine kidney (MDCK) cells were examined. Sequencing analysis revealed substitutions of D190V/N or D225G in the haemagglutinin (HA) proteins in egg isolates, whereas MDCK isolates retained HA genes identical to those of the original viruses present in the clinical samples. Egg isolates with substitution of either D190V/N or D225G had increased haemagglutinating activity for mouse and sheep erythrocytes, but reduced activity for rabbit erythrocytes. Additionally, egg isolates with D225G had increased haemagglutination activity for chicken erythrocytes. A direct binding assay using a sialyl glycopolymer that possessed either a 5-N-acetylneuraminic acid (Neu5Ac) alpha2,6galactose (Gal) or a Neu5Acalpha2,3Gal linkage revealed that the egg isolates used in this study showed higher binding activity to the Neu5Acalpha2,3Gal receptor than MDCK isolates. Increased binding activity of the egg isolates to the Neu5Acalpha2,3Gal receptor was also confirmed by haemagglutination assay with resialylated chicken erythrocytes by Galbeta1,3/4GlcNAcalpha2,3-sialyltransferase. These observations were reinforced by flow-cytometric and N-glycan analyses of the erythrocytes. The alpha2,3-linked sialic acids were expressed predominantly on the surface of mouse and sheep erythrocytes. Chicken erythrocytes expressed Neu5Acalpha2,3Gal more abundantly than Neu5Acalpha2,6Gal, and rabbit erythrocytes expressed both 5-N-glycolylneuraminic acid (Neu5Gc) alpha2,6Gal and Neu5Acalpha2,6Gal. Our results demonstrate clearly that classical H1 SIVs undergo alterations in receptor-binding activity associated with an amino acid substitution in the HA protein during isolation and propagation in embryonated chicken eggs.Journal of General Virology 12/2009; 91(Pt 4):938-48. · 3.36 Impact Factor -
Article: Molecular epidemiological analysis of highly pathogenic avian influenza H5N1 subtype isolated from poultry and wild bird in Thailand.
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ABSTRACT: A comprehensive molecular epidemiological analysis was performed on highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype derived from poultry and wild bird during 2004-2007 in Thailand. Sequence analysis followed by phylogenetic analysis was applied to all eight segments of the viruses. Viruses belonging to clades 1 and 2.3.4 in the HA phylogenetic tree have been shown to circulate in Thailand. Our analysis revealed differential evolution of the HPAI viruses among clade 1 strains. Isolates from Phichit province in 2006 resided in two distinct branches, designated 1.p1 and 1.p2. A hemagglutination inhibition test with a panel of monoclonal antibodies demonstrated a possible antigenic drift between the Phichit isolates. Involvement of free-grazing duck practice in the area was discussed as a cause of the differential evolution among the Phichit isolates. A branch, designated 1-TGWB and consisting exclusively of isolates from zoological tigers and wild birds, was evident in all phylogenetic trees constructed in the study. The branch's existence indicated that the HPAI viruses could have been maintained in the wild bird population for a certain period, although no involvement of wild birds in HPAI transmission to poultry was evident in this study.Virus Research 10/2008; 138(1-2):70-80. · 2.94 Impact Factor
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2008–2012
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National Institute of Animal Health
Ibaraki, Osaka-fu, Japan
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