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Zhang H, Han S, Wang B, Xing Y, Yuan G, Wang Y, Zhao Z, Li G, Li Q, Pan J, Li W, He H. Genetic Characterization and Pathogenesis of Avian Influenza Virus H3N8 Isolated from Chinese pond heron in China in 2021. Viruses 2023; 15. [PMID: 36851597 DOI: 10.3390/v15020383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 01/31/2023] Open
Abstract
In October 2021, a wild bird-origin H3N8 influenza virus-A/Chinese pond heron/Jiangxi 5-1/2021 (H3N8)-was isolated from Chinese pond heron in China. Phylogenetic and molecular analyses were performed to characterize the genetic origin of the H3N8 strain. Phylogenetic analysis revealed that eight gene segments of this avian influenza virus H3N8 belong to Eurasian lineages. HA gene clustered with avian influenza viruses is circulating in poultry in southern China. The NA gene possibly originated from wild ducks in South Korea and has the highest homology (99.3%) with A/Wild duck/South Korea/KNU2020-104/2020 (H3N8), while other internal genes have a complex and wide range of origins. The HA cleavage site is PEKQTR↓GLF with one basic amino acid, Q226 and T228 at HA preferentially bind to the alpha-2,3-linked sialic acid receptor, non-deletion of the stalk region in the NA gene and no mutations at E627K and D701N of the PB2 protein, indicating that isolate A/Chinese pond heron/Jiangxi 5-1/2021 (H3N8) was a typical avian influenza with low pathogenicity. However, there are some mutations that may increase pathogenicity and transmission in mammals, such as N30D, T215A of M1 protein, and P42S of NS1 protein. In animal studies, A/Chinese pond heron/Jiangxi 5-1/2021 (H3N8) replicates inefficiently in the mouse lung and does not adapt well to the mammalian host. Overall, A/Chinese pond heron/Jiangxi 5-1/2021 (H3N8) is a novel wild bird-origin H3N8 influenza virus reassortant from influenza viruses of poultry and wild birds. This wild bird-origin avian influenza virus is associated with wild birds along the East Asian-Australasian flyway. Therefore, surveillance of avian influenza viruses in wild birds should be strengthened to assess their mutation and pandemic risk in advance.
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Lin P, Jin T, Yu X, Liang L, Liu G, Jovic D, Sun Z, Yu Z, Pan J, Fan G. Composition and Dynamics of H1N1 and H7N9 Influenza A Virus Quasispecies in a Co-infected Patient Analyzed by Single Molecule Sequencing Technology. Front Genet 2021; 12:754445. [PMID: 34804122 PMCID: PMC8595946 DOI: 10.3389/fgene.2021.754445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/10/2021] [Indexed: 11/22/2022] Open
Abstract
A human co-infected with H1N1 and H7N9 subtypes influenza A virus (IAV) causes a complex infectious disease. The identification of molecular-level variations in composition and dynamics of IAV quasispecies will help to understand the pathogenesis and provide guidance for precision medicine treatment. In this study, using single-molecule real-time sequencing (SMRT) technology, we successfully acquired full-length IAV genomic sequences and quantified their genotypes abundance in serial samples from an 81-year-old male co-infected with H1N1 and H7N9 subtypes IAV. A total of 26 high diversity nucleotide loci was detected, in which the A-G base transversion was the most abundant substitution type (67 and 64%, in H1N1 and H7N9, respectively). Seven significant amino acid variations were detected, such as NA:H275Y and HA: R222K in H1N1 as well as PB2:E627K and NA: K432E in H7N9, which are related to viral drug-resistance or mammalian adaptation. Furtherly, we retrieved 25 H1N1 and 22 H7N9 genomic segment haplotypes from the eight samples based on combining high-diversity nucleotide loci, which provided a more concise overview of viral quasispecies composition and dynamics. Our approach promotes the popularization of viral quasispecies analysis in a complex infectious disease, which will boost the understanding of viral infections, pathogenesis, evolution, and precision medicine.
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Affiliation(s)
- Peng Lin
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.,BGI-Qingdao, BGI-Shenzhen, Qingdao, China
| | - Tao Jin
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China.,BGI-Shenzhen, Shenzhen, China
| | - Xinfen Yu
- Hangzhou Center for Disease Control and Prevention, Hangzhou, China
| | | | - Guang Liu
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China
| | | | - Zhou Sun
- Hangzhou Center for Disease Control and Prevention, Hangzhou, China
| | - Zhe Yu
- BGI-Shenzhen, Shenzhen, China
| | - Jingcao Pan
- Hangzhou Center for Disease Control and Prevention, Hangzhou, China
| | - Guangyi Fan
- BGI-Qingdao, BGI-Shenzhen, Qingdao, China.,BGI-Shenzhen, Shenzhen, China
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Duong BT, Bal J, Sung HW, Yeo SJ, Park H. Molecular Analysis of the Avian H7 Influenza Viruses Circulating in South Korea during 2018-2019: Evolutionary Significance and Associated Zoonotic Threats. Viruses 2021; 13:v13112260. [PMID: 34835066 PMCID: PMC8623559 DOI: 10.3390/v13112260] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/04/2021] [Accepted: 11/08/2021] [Indexed: 12/18/2022] Open
Abstract
Avian influenza virus (AIV) subtypes H5 and H7, possessing the ability to mutate spontaneously from low pathogenic (LP) to highly pathogenic (HP) variants, are major concerns for enormous socio-economic losses in the poultry industry, as well as for fatal human infections. Through antigenic drift and shift, genetic reassortments of the genotypes pose serious threats of increased virulence and pathogenicity leading to potential pandemics. In this study, we isolated the H7-subtype AIVs circulating in the Republic of Korea during 2018–2019, and perform detailed molecular analysis to study their circulation, evolution, and possible emergence as a zoonotic threat. Phylogenetic and nucleotide sequence analyses of these isolates revealed their distribution into two distinct clusters, with the HA gene sharing the highest nucleotide identity with either the A/common teal/Shanghai/CM1216/2017, isolated from wild birds in Shanghai, China, or the A/duck/Shimane/2014, isolated from Japan. Mutations were found in HA (S138A (H3 numbering)), M1 (N30D and T215A), NS1 (P42S), PB2 (L89V), and PA (H266R and F277S) proteins—the mutations had previously been reported to be related to mammalian adaptation and changes in the virulence of AIVs. Taken together, the results firmly put forth the demand for routine surveillance of AIVs in wild birds to prevent possible pandemics arising from reassortant AIVs.
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Affiliation(s)
- Bao Tuan Duong
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (B.T.D.); (J.B.)
| | - Jyotiranjan Bal
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (B.T.D.); (J.B.)
| | - Haan Woo Sung
- College of Veterinary Medicine, Kangwon National University, Chuncheon-si 24341, Korea
- Correspondence: (H.W.S.); (S.-J.Y.); (H.P.)
| | - Seon-Ju Yeo
- Department of Tropical Medicine and Parasitology, Seoul National University College of Medicine, Seoul 03080, Korea
- Correspondence: (H.W.S.); (S.-J.Y.); (H.P.)
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (B.T.D.); (J.B.)
- Correspondence: (H.W.S.); (S.-J.Y.); (H.P.)
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Nguyen ATV, Hoang VT, Sung HW, Yeo SJ, Park H. Genetic Characterization and Pathogenesis of Three Novel Reassortant H5N2 Viruses in South Korea, 2018. Viruses 2021; 13:v13112192. [PMID: 34834997 PMCID: PMC8619638 DOI: 10.3390/v13112192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 10/26/2021] [Accepted: 10/26/2021] [Indexed: 12/03/2022] Open
Abstract
The outbreaks of H5N2 avian influenza viruses have occasionally caused the death of thousands of birds in poultry farms. Surveillance during the 2018 winter season in South Korea revealed three H5N2 isolates in feces samples collected from wild birds (KNU18-28: A/Wild duck/South Korea/KNU18-28/2018, KNU18-86: A/Bean Goose/South Korea/KNU18-86/2018, and KNU18-93: A/Wild duck/South Korea/KNU18-93/2018). Phylogenetic tree analysis revealed that these viruses arose from reassortment events among various virus subtypes circulating in South Korea and other countries in the East Asia–Australasian Flyway. The NS gene of the KNU18-28 and KNU18-86 isolates was closely related to that of China’s H10N3 strain, whereas the KNU18-93 strain originated from the H12N2 strain in Japan, showing two different reassortment events and different from a low pathogenic H5N3 (KNU18-91) virus which was isolated at the same day and same place with KNU18-86 and KNU18-93. These H5N2 isolates were characterized as low pathogenic avian influenza viruses. However, many amino acid changes in eight gene segments were identified to enhance polymerase activity and increase adaptation and virulence in mice and mammals. Experiments reveal that viral replication in MDCK cells was quite high after 12 hpi, showing the ability to replicate in mouse lungs. The hematoxylin and eosin-stained (H&E) lung sections indicated different degrees of pathogenicity of the three H5N2 isolates in mice compared with that of the control H1N1 strain. The continuing circulation of these H5N2 viruses may represent a potential threat to mammals and humans. Our findings highlight the need for intensive surveillance of avian influenza virus circulation in South Korea to prevent the risks posed by these reassortment viruses to animal and public health.
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Affiliation(s)
- Anh Thi Viet Nguyen
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (A.T.V.N.); (V.T.H.)
| | - Vui Thi Hoang
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (A.T.V.N.); (V.T.H.)
| | - Haan Woo Sung
- College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea;
| | - Seon-Ju Yeo
- Department of Tropical Medicine and Parasitology, College of Medicine, Seoul National University, Seoul 03080, Korea
- Correspondence: (S.-J.Y.); (H.P.)
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (A.T.V.N.); (V.T.H.)
- Correspondence: (S.-J.Y.); (H.P.)
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Trinh TT, Tiwari I, Durairaj K, Duong BT, Nguyen ATV, Tuong HT, Hoang VT, Than DD, Nam S, Yeo SJ, Park H. Genetic Characterization and Pathogenesis of Avian Influenza Virus H7N3 Isolated from Spot-Billed Ducks in South Korea, Early 2019. Viruses 2021; 13:856. [PMID: 34067187 DOI: 10.3390/v13050856] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 05/01/2021] [Accepted: 05/04/2021] [Indexed: 11/29/2022] Open
Abstract
Low-pathogenicity avian influenza viruses (LPAIV) introduced by migratory birds circulate in wild birds and can be transmitted to poultry. These viruses can mutate to become highly pathogenic avian influenza viruses causing severe disease and death in poultry. In March 2019, an H7N3 avian influenza virus—A/Spot-billed duck/South Korea/WKU2019-1/2019 (H7N3)—was isolated from spot-billed ducks in South Korea. This study aimed to evaluate the phylogenetic and mutational analysis of this isolate. Molecular analysis revealed that the genes for HA (hemagglutinin) and NA (neuraminidase) of this strain belonged to the Central Asian lineage, whereas genes for other internal proteins such as polymerase basic protein 1 (PB1), PB2, nucleoprotein, polymerase acidic protein, matrix protein, and non-structural protein belonged to that of the Korean lineage. In addition, a monobasic amino acid (PQIEPR/GLF) at the HA cleavage site, and the non-deletion of the stalk region in the NA gene indicated that this isolate was a typical LPAIV. Nucleotide sequence similarity analysis of HA revealed that the highest homology (99.51%) of this isolate is to that of A/common teal/Shanghai/CM1216/2017 (H7N7), and amino acid sequence of NA (99.48%) was closely related to that of A/teal/Egypt/MB-D-487OP/2016 (H7N3). An in vitro propagation of the A/Spot-billed duck/South Korea/WKU2019-1/2019 (H7N3) virus showed highest (7.38 Log10 TCID50/mL) virus titer at 60 h post-infection, and in experimental mouse lungs, the virus was detected at six days’ post-infection. Our study characterizes genetic mutations, as well as pathogenesis in both in vitro and in vivo model of a new Korea H7N3 viruses in 2019, carrying multiple potential mutations to become highly pathogenic and develop an ability to infect humans; thus, emphasizing the need for routine surveillance of avian influenza viruses in wild birds.
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Mercan Y, Atim G, Kayed AE, Azbazdar ME, Kandeil A, Ali MA, Rubrum A, McKenzie P, Webby RJ, Erima B, Wabwire-Mangen F, Ukuli QA, Tugume T, Byarugaba DK, Kayali G, Ducatez MF, Koçer ZA. Molecular Characterization of Closely Related H6N2 Avian Influenza Viruses Isolated from Turkey, Egypt, and Uganda. Viruses 2021; 13:v13040607. [PMID: 33918166 PMCID: PMC8065897 DOI: 10.3390/v13040607] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/28/2021] [Accepted: 03/30/2021] [Indexed: 01/22/2023] Open
Abstract
Genetic analysis of circulating avian influenza viruses (AIVs) in wild birds at different geographical regions during the same period could improve our knowledge about virus transmission dynamics in natural hosts, virus evolution as well as zoonotic potential. Here, we report the genetic and molecular characterization of H6N2 influenza viruses isolated from migratory birds in Turkey, Egypt, and Uganda during 2017–2018. The Egyptian and Turkish isolates were genetically closer to each other than they were to the virus isolated from Uganda. Our results also suggest that multiple reassortment events were involved in the genesis of the isolated viruses. All viruses contained molecular markers previously associated with increased replication and/or pathogenicity in mammals. The results of this study indicate that H6N2 viruses carried by migratory birds on the West Asian/East African and Mediterranean/Black Sea flyways have the potential to transmit to mammals including humans. Additionally, adaptation markers in these viruses indicate the potential risk for poultry, which also increases the possibility of human exposure to these viruses.
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Affiliation(s)
- Yavuz Mercan
- Emerging Viral Diseases Laboratory, Izmir Biomedicine and Genome Center, 35340 Izmir, Turkey; (Y.M.); (M.E.A.)
- Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, 35340 Izmir, Turkey
| | - Gladys Atim
- Makerere University Walter Reed Project, P.O. Box 7062 Kampala, Uganda; (G.A.); (B.E.); (F.W.-M.); (Q.A.U.); (T.T.); (D.K.B.)
| | - Ahmed E. Kayed
- Center of Scientific Excellence for Influenza Viruses, National Research Centre, Giza 12311, Egypt; (A.E.K.); (A.K.); (M.A.A.)
| | - M. Ekin Azbazdar
- Emerging Viral Diseases Laboratory, Izmir Biomedicine and Genome Center, 35340 Izmir, Turkey; (Y.M.); (M.E.A.)
- Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, 35340 Izmir, Turkey
| | - Ahmed Kandeil
- Center of Scientific Excellence for Influenza Viruses, National Research Centre, Giza 12311, Egypt; (A.E.K.); (A.K.); (M.A.A.)
| | - Mohamed A. Ali
- Center of Scientific Excellence for Influenza Viruses, National Research Centre, Giza 12311, Egypt; (A.E.K.); (A.K.); (M.A.A.)
| | - Adam Rubrum
- St Jude Children’s Research Hospital, Memphis, TN 38105, USA; (A.R.); (P.M.); (R.J.W.)
| | - Pamela McKenzie
- St Jude Children’s Research Hospital, Memphis, TN 38105, USA; (A.R.); (P.M.); (R.J.W.)
| | - Richard J. Webby
- St Jude Children’s Research Hospital, Memphis, TN 38105, USA; (A.R.); (P.M.); (R.J.W.)
| | - Bernard Erima
- Makerere University Walter Reed Project, P.O. Box 7062 Kampala, Uganda; (G.A.); (B.E.); (F.W.-M.); (Q.A.U.); (T.T.); (D.K.B.)
| | - Fred Wabwire-Mangen
- Makerere University Walter Reed Project, P.O. Box 7062 Kampala, Uganda; (G.A.); (B.E.); (F.W.-M.); (Q.A.U.); (T.T.); (D.K.B.)
- School of Public Health, Makerere University, P.O. Box 7062 Kampala, Uganda
| | - Qouilazoni A. Ukuli
- Makerere University Walter Reed Project, P.O. Box 7062 Kampala, Uganda; (G.A.); (B.E.); (F.W.-M.); (Q.A.U.); (T.T.); (D.K.B.)
| | - Titus Tugume
- Makerere University Walter Reed Project, P.O. Box 7062 Kampala, Uganda; (G.A.); (B.E.); (F.W.-M.); (Q.A.U.); (T.T.); (D.K.B.)
| | - Denis K. Byarugaba
- Makerere University Walter Reed Project, P.O. Box 7062 Kampala, Uganda; (G.A.); (B.E.); (F.W.-M.); (Q.A.U.); (T.T.); (D.K.B.)
- College of Veterinary Medicine, Makerere University, P.O. Box 7062 Kampala, Uganda
| | - Ghazi Kayali
- Department of Epidemiology, Human Genetics, and Environmental Sciences, University of Texas, Houston, TX 77030, USA;
- Human Link, Dubai, United Arab Emirates
| | | | - Zeynep A. Koçer
- Emerging Viral Diseases Laboratory, Izmir Biomedicine and Genome Center, 35340 Izmir, Turkey; (Y.M.); (M.E.A.)
- Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, 35340 Izmir, Turkey
- Correspondence: ; Tel.: +90-232-299-4165
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Trinh TTT, Duong BT, Nguyen ATV, Tuong HT, Hoang VT, Than DD, Nam S, Sung HW, Yun KJ, Yeo SJ, Park H. Emergence of Novel Reassortant H1N1 Avian Influenza Viruses in Korean Wild Ducks in 2018 and 2019. Viruses 2020; 13:v13010030. [PMID: 33375376 PMCID: PMC7823676 DOI: 10.3390/v13010030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 12/19/2020] [Accepted: 12/24/2020] [Indexed: 02/08/2023] Open
Abstract
Influenza A virus subtype H1N1 has caused global pandemics like the “Spanish flu” in 1918 and the 2009 H1N1 pandemic several times. H1N1 remains in circulation and survives in multiple animal sources, including wild birds. Surveillance during the winter of 2018–2019 in Korea revealed two H1N1 isolates in samples collected from wild bird feces: KNU18-64 (A/Greater white-fronted goose/South Korea/KNU18-64/2018(H1N1)) and WKU19-4 (A/wild bird/South Korea/WKU19-4/2019(H1N1)). Phylogenetic analysis indicated that M gene of KNU18-64(H1N1) isolate resembles that of the Alaskan avian influenza virus, whereas WKU19-4(H1N1) appears to be closer to the Mongolian virus. Molecular characterization revealed that they harbor the amino acid sequence PSIQRS↓GLF and are low-pathogenicity influenza viruses. In particular, the two isolates harbored three different mutation sites, indicating that they have different virulence characteristics. The mutations in the PB1-F2 and PA protein of WKU19-4(H1N1) indicate increasing polymerase activity. These results corroborate the kinetic growth data for WKU19-4 in MDCK cells: a dramatic increase in the viral titer after 12 h post-inoculation compared with that in the control group H1N1 (CA/04/09(pdm09)). The KNU18-64(H1N1) isolate carries mutations indicating an increase in mammal adaptation; this characterization was confirmed by the animal study in mice. The KNU18-64(H1N1) group showed the presence of viruses in the lungs at days 3 and 6 post-infection, with titers of 2.71 ± 0.16 and 3.71 ± 0.25 log10(TCID50/mL), respectively, whereas the virus was only detected in the WKU19-4(H1N1) group at day 6 post-infection, with a lower titer of 2.75 ± 0.51 log10(TCID50/mL). The present study supports the theory that there is a relationship between Korea and America with regard to reassortment to produce novel viral strains. Therefore, there is a need for increased surveillance of influenza virus circulation in free-flying and wild land-based birds in Korea, particularly with regard to Alaskan and Asian strains.
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Affiliation(s)
- Thuy-Tien Thi Trinh
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
| | - Bao Tuan Duong
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
| | - Anh Thi Viet Nguyen
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
| | - Hien Thi Tuong
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
| | - Vui Thi Hoang
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
| | - Duong Duc Than
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
| | - SunJeong Nam
- Division of EcoScience, Ewha University, Seoul 03760, Korea;
| | - Haan Woo Sung
- College of Veterinary Medicine, Kangwon National University, Chuncheon 200-701, Korea;
| | - Ki-Jung Yun
- Department of Pathology, School of Medicine, Wonkwang University, Iksan 570-749, Korea;
| | - Seon-Ju Yeo
- Department of Tropical Medicine and Parasitology, College of Medicine, Seoul National University, Seoul 03080, Korea
- Correspondence: (S.-J.Y.); (H.P.)
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea; (T.-T.T.T.); (B.T.D.); (A.T.V.N.); (H.T.T.); (V.T.H.); (D.D.T.)
- Correspondence: (S.-J.Y.); (H.P.)
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Liu WJ, Li J, Zou R, Pan J, Jin T, Li L, Liu P, Zhao Y, Yu X, Wang H, Liu G, Jiang H, Bi Y, Liu L, Yuen KY, Liu Y, Gao GF. Dynamic PB2-E627K substitution of influenza H7N9 virus indicates the in vivo genetic tuning and rapid host adaptation. Proc Natl Acad Sci U S A 2020; 117:23807-23814. [PMID: 32873642 PMCID: PMC7519270 DOI: 10.1073/pnas.2013267117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Avian-origin influenza viruses overcome the bottleneck of the interspecies barrier and infect humans through the evolution of variants toward more efficient replication in mammals. The dynamic adaptation of the genetic substitutions and the correlation with the virulence of avian-origin influenza virus in patients remain largely elusive. Here, based on the one-health approach, we retrieved the original virus-positive samples from patients with H7N9 and their surrounding poultry/environment. The specimens were directly deep sequenced, and the subsequent big data were integrated with the clinical manifestations. Unlike poultry/environment-derived samples with the consistent dominance of avian signature 627E of H7N9 polymerase basic protein 2 (PB2), patient specimens had diverse ratios of mammalian signature 627K, indicating the rapid dynamics of H7N9 adaptation in patients during the infection process. In contrast, both human- and poultry/environment-related viruses had constant dominance of avian signature PB2-701D. The intrahost dynamic adaptation was confirmed by the gradual replacement of 627E by 627K in H7N9 in the longitudinally collected specimens from one patient. These results suggest that host adaptation for better virus replication to new hosts, termed "genetic tuning," actually occurred in H7N9-infected patients in vivo. Notably, our findings also demonstrate the correlation between rapid host adaptation of H7N9 PB2-E627K and the fatal outcome and disease severity in humans. The feature of H7N9 genetic tuning in vivo and its correlation with the disease severity emphasize the importance of testing for the evolution of this avian-origin virus during the course of infection.
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Affiliation(s)
- William J Liu
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Diseases, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, 518112 Shenzhen, China
- NHC Key Laboratory of Biosafety, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206 Beijing, China
| | - Jun Li
- Hangzhou Center for Disease Control and Prevention, 310021 Hangzhou, China
| | - Rongrong Zou
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Diseases, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, 518112 Shenzhen, China
| | - Jingcao Pan
- Hangzhou Center for Disease Control and Prevention, 310021 Hangzhou, China
| | - Tao Jin
- BGI-Shenzhen, 518083 Shenzhen, China
- China National GeneBank, BGI-Shenzhen, 518083 Shenzhen, China
| | | | - Peipei Liu
- NHC Key Laboratory of Biosafety, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206 Beijing, China
| | - Yingze Zhao
- NHC Key Laboratory of Biosafety, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206 Beijing, China
| | - Xinfen Yu
- Hangzhou Center for Disease Control and Prevention, 310021 Hangzhou, China
| | - Haoqiu Wang
- Hangzhou Center for Disease Control and Prevention, 310021 Hangzhou, China
| | - Guang Liu
- BGI-Shenzhen, 518083 Shenzhen, China
- China National GeneBank, BGI-Shenzhen, 518083 Shenzhen, China
| | - Hui Jiang
- BGI-Shenzhen, 518083 Shenzhen, China
- China National GeneBank, BGI-Shenzhen, 518083 Shenzhen, China
| | - Yuhai Bi
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Diseases, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, 518112 Shenzhen, China
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
- Center for Influenza Research and Early-Warning, Chinese Academy of Sciences, 100101 Beijing, China
| | - Lei Liu
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Diseases, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, 518112 Shenzhen, China
| | - Kwok-Yung Yuen
- State Key Laboratory of Emerging Infectious Diseases and the HKU-Shenzhen Hospital, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Yingxia Liu
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Diseases, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, 518112 Shenzhen, China;
| | - George F Gao
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Diseases, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, 518112 Shenzhen, China;
- NHC Key Laboratory of Biosafety, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206 Beijing, China
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
- Center for Influenza Research and Early-Warning, Chinese Academy of Sciences, 100101 Beijing, China
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9
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Nguyen NM, Sung HW, Yun KJ, Park H, Yeo SJ. Genetic Characterization of a Novel North American-Origin Avian Influenza A (H6N5) Virus Isolated from Bean Goose of South Korea in 2018. Viruses 2020; 12:v12070774. [PMID: 32709116 PMCID: PMC7411716 DOI: 10.3390/v12070774] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/19/2022] Open
Abstract
The complex overlap in waterfowl migratory pathways across the world has established numerous occurrences of genetic reassortment and intercontinental spread of avian influenza virus (AIV) over long distances, thereby calling for huge efforts and targeted surveillance for infection control. During annual surveillance in South Korea in 2018, a novel avian influenza H6N5 (K6) subtype was isolated from the fecal sample of wild bird. Genomic characterization using a phylogenetic tree indicated the K6 virus to be of North American-origin, with partial homology to an H6N5 strain, A/Aix galericulata/South Korea/K17-1638-5/2017 (K17). A monobasic residue at the HA cleavage site and absence of a notable mutation at the HA receptor-binding site suggested the isolate to be of low pathogenicity. However, molecular analysis revealed the E119V mutation in the NA gene and a human host marker mutation E382D in the polymerase acidic (PA) gene, implying their susceptibility to neuraminidase inhibitors and potential infectivity in humans, respectively. For comparison, K6 and K17 were found to be dissimilar for various mutations, such as A274T of PB2, S375N/T of PB1, or V105M of NP, each concerning the increased virulence of K6 in mammalian system. Moreover, kinetic data presented the highest viral titer of this H6N5 isolate at 106.37 log10TCID50 after 48 h of infection, thus proving efficient adaptability for replication in a mammalian system in vitro. The mouse virus challenge study showed insignificant influence on the total body weight, while viral load shedding in lungs peaked at 1.88 ± 0.21 log10 TICD50/mL, six days post infection. The intercontinental transmission of viruses from North America may continuously be present in Korea, thereby providing constant opportunities for virus reassortment with local resident AIVs; these results hint at the increased potential risk of host jumping capabilities of the new isolates. Our findings reinforce the demand for regular surveillance, not only in Korea but also along the flyways in Alaska.
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Affiliation(s)
- Ngoc Minh Nguyen
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea;
| | - Haan Woo Sung
- College of Veterinary Medicine, Kangwon National University, Chuncheon 200-701, Korea;
| | - Ki-Jung Yun
- Department of Pathology, School of Medicine, Wonkwang University, Iksan 570-749, Korea;
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea;
- Correspondence: (H.P.); (S.-J.Y.)
| | - Seon-Ju Yeo
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 570-749, Korea;
- Correspondence: (H.P.); (S.-J.Y.)
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10
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Yeo SJ, Than DD, Park HS, Sung HW, Park H. Molecular Characterization of a Novel Avian Influenza A (H2N9) Strain Isolated from Wild Duck in Korea in 2018. Viruses 2019; 11:v11111046. [PMID: 31717636 PMCID: PMC6893532 DOI: 10.3390/v11111046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/02/2019] [Accepted: 11/06/2019] [Indexed: 01/03/2023] Open
Abstract
A novel avian influenza virus (A/wild duck/Korea/K102/2018) (H2N9) was isolated from wild birds in South Korea in 2018, and phylogenetic and molecular analyses were conducted on complete gene sequences obtained by next-generation sequencing. Phylogenetic analysis indicated that the hemagglutinin (HA) and neuraminidase (NA) genes of the A/wild duck/Korea/K102/2018 (H2N9) virus belonged to the Eurasian countries, whereas other internal genes (polymerase basic protein 1 (PB1), PB2, nucleoprotein (NP), polymerase acidic protein (PA), matrix protein (M), and non-structural protein (NS)) belonged to the East Asian countries. A monobasic amino acid (PQIEPR/GLF) at the HA cleavage site, E627 in the PB2 gene, and no deletion of the stalk region in the NA gene indicated that the A/wild duck/Korea/K102/2018 (H2N9) isolate was a typical low pathogenicity avian influenza (LPAI). Nucleotide sequence similarity analysis of HA revealed that the highest homology (98.34%) is to that of A/duck/Mongolia/482/2015 (H2N3), and amino acid sequence of NA was closely related to that of A/duck/Bangladesh/8987/2010 (H10N9) (96.45%). In contrast, internal genes showed homology higher than 98% compared to those of other isolates derived from duck and wild birds of China or Japan in 2016–2018. The newly isolated A/wild duck/Korea/K102/2018 (H2N9) strain is the first reported avian influenza virus in Korea, and may have evolved from multiple genotypes in wild birds and ducks in Mongolia, China, and Japan.
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Affiliation(s)
- Seon-Ju Yeo
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (S.-J.Y.); (D.-D.T.)
| | - Duc-Duong Than
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (S.-J.Y.); (D.-D.T.)
| | - Hong-Seog Park
- GnCBio Inc, 4F, Yegan Plaza, 36, Banseok-ro, Yuseong-gu, Daejeon 34069, Korea;
| | - Haan Woo Sung
- College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea
- Correspondence: (H.W.S.); (H.P.)
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea; (S.-J.Y.); (D.-D.T.)
- Correspondence: (H.W.S.); (H.P.)
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11
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Yu Z, Cheng K, Sun W, Zhang X, Xia X, Gao Y. Multiple adaptive amino acid substitutions increase the virulence of a wild waterfowl-origin reassortant H5N8 avian influenza virus in mice. Virus Res 2017; 244:13-20. [PMID: 29113821 DOI: 10.1016/j.virusres.2017.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/26/2017] [Accepted: 11/02/2017] [Indexed: 10/18/2022]
Abstract
A novel H5N8 highly pathogenic avian influenza virus (HPAIV) caused poultry outbreaks in the Republic of Korea in 2014. The novel H5N8 HPAIV has spread to Asia, Europe, and North America and caused great public concern from then on. Here, we generated mouse-adapted variants of a wild waterfowl-origin H5N8 HPAIV to identify adaptive mutants that confer enhanced pathogenicity in mammals. The mouse lethal doses (MLD50) of the mouse-adapted variants were reduced 31623-fold compared to the wild-type (WT) virus. Mouse-adapted variants displayed enhanced replication in vitro and in vivo, and expanded tissue tropism in mice. Sequence analysis revealed four amino acid substitutions in the PB2 (E627K), PA (F35S), HA (R227H), and NA (I462V) proteins. These data suggest that multiple amino acid substitutions collaboratively increase the virulence of a wild bird-origin reassortant H5N8 HPAIV and cause severe disease in mice.
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Affiliation(s)
- Zhijun Yu
- Institute of Poultry Science, Shandong Academy of Agricultural Sciences, Jinan, 250023, China.
| | - Kaihui Cheng
- Dairy Cattle Research Center, Shandong Academy of Agricultural Sciences, Jinan, 250132, China
| | - Weiyang Sun
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Military Veterinary Research Institute, Academy of Military Medical Sciences, Changchun, 130122, China
| | - Xinghai Zhang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Military Veterinary Research Institute, Academy of Military Medical Sciences, Changchun, 130122, China
| | - Xianzhu Xia
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Military Veterinary Research Institute, Academy of Military Medical Sciences, Changchun, 130122, China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
| | - Yuwei Gao
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Military Veterinary Research Institute, Academy of Military Medical Sciences, Changchun, 130122, China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
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12
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Choi WS, Lloren KKS, Baek YH, Song MS. The significance of avian influenza virus mouse-adaptation and its application in characterizing the efficacy of new vaccines and therapeutic agents. Clin Exp Vaccine Res 2017; 6:83-94. [PMID: 28775972 PMCID: PMC5540968 DOI: 10.7774/cevr.2017.6.2.83] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 05/03/2017] [Accepted: 05/12/2017] [Indexed: 11/26/2022] Open
Abstract
Due to the increased frequency of interspecies transmission of avian influenza viruses, studies designed to identify the molecular determinants that could lead to an expansion of the host range have been increased. A variety of mouse-based mammalian-adaptation studies of avian influenza viruses have provided insight into the genetic alterations of various avian influenza subtypes that may contribute to the generation of a pandemic virus. To date, the studies have focused on avian influenza subtypes H5, H6, H7, H9, and H10 which have recently caused human infection. Although mice cannot fully reflect the course of human infection with avian influenza, these mouse studies can be a useful method for investigating potential mammalian adaptive markers against newly emerging avian influenza viruses. In addition, due to the lack of appropriate vaccines against the diverse emerging influenza viruses, the generation of mouse-adapted lethal variants could contribute to the development of effective vaccines or therapeutic agents. Within this review, we will summarize studies that have demonstrated adaptations of avian influenza viruses that result in an altered pathogenicity in mice which may suggest the potential application of mouse-lethal strains in the development of influenza vaccines and/or therapeutics in preclinical studies.
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Affiliation(s)
- Won-Suk Choi
- Department of Microbiology, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Korea
| | - Khristine Kaith S Lloren
- Department of Microbiology, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Korea
| | - Yun Hee Baek
- Department of Microbiology, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Korea
| | - Min-Suk Song
- Department of Microbiology, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Korea
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13
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Thuy DM, Peacock TP, Bich VTN, Fabrizio T, Hoang DN, Tho ND, Diep NT, Nguyen M, Hoa LNM, Trang HTT, Choisy M, Inui K, Newman S, Trung NV, van Doorn R, To TL, Iqbal M, Bryant JE. Prevalence and diversity of H9N2 avian influenza in chickens of Northern Vietnam, 2014. Infect Genet Evol 2016; 44:530-540. [PMID: 27340015 PMCID: PMC5036934 DOI: 10.1016/j.meegid.2016.06.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/17/2016] [Accepted: 06/19/2016] [Indexed: 12/23/2022]
Abstract
Despite their classification as low pathogenicity avian influenza viruses (LPAIV), A/H9N2 viruses cause significant losses in poultry in many countries throughout Asia, the Middle East and North Africa. To date, poultry surveillance in Vietnam has focused on detection of influenza H5 viruses, and there is limited understanding of influenza H9 epidemiology and transmission dynamics. We determined prevalence and diversity of influenza A viruses in chickens from live bird markets (LBM) of 7 northern Vietnamese provinces, using pooled oropharyngeal swabs collected from October to December 2014. Screening by real time RT-PCR revealed 1207/4900 (24.6%) of pooled swabs to be influenza A virus positive; overall prevalence estimates after accounting for pooling (5 swabs/pools) were 5.8% (CI 5.4–6.0). Subtyping was performed on 468 pooled swabs with M gene Ct < 26. No influenza H7 was detected; 422 (90.1%) were H9 positive; and 22 (4.7%) were H5 positive. There was no evidence was of interaction between H9 and H5 virus detection rates. We sequenced 17 whole genomes of A/H9N2, 2 of A/H5N6, and 11 partial genomes. All H9N2 viruses had internal genes that clustered with genotype 57 and were closely related to Chinese human isolates of A/H7N9 and A/H10N8. Using a nucleotide divergence cutoff of 98%, we identified 9 distinct H9 genotypes. Phylogenetic analysis suggested multiple introductions of H9 viruses to northern Vietnam rather than in-situ transmission. Further investigations of H9 prevalence and diversity in other regions of Vietnam are warranted to assess H9 endemicity elsewhere in the country. We report detection of highly pathogenic avian influenza (HPAI) from healthy chickens in Live Bird Markets of Vietnam. Because all breeds of domestic chickens are extremely susceptible to HPAI, we speculate that HPAI detections from market chickens may reflect infections that occur after arrival in the market. Alternatively, shedding of HPAI from healthy birds may reflect vaccine-induced protective immunity that mitigates disease but does not block viral infection. As many as 49% of all pooled surveillance swabs were positive for influenza A virus, corresponding to an overall Influenza A prevalence of 5.45% (95% Confidence Interval 5.4-6.0%). Low pathogenicity avian influenza (LPAI) H9N2 accounted for the vast majority of all influenza A detections in market chickens sampled from 9 northern provinces. To date there is no evidence to suggest an interaction effect between circulation of H5 and H9 viruses; however sampling strategies that involve pooling of surveillance swabs from multiple birds greatly complicates the assessment of co-infection rates or evaluation of epidemiological associations.
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Affiliation(s)
- Duong Mai Thuy
- National Center for Veterinary Diagnostics, Department of Animal Health, Hanoi, Vietnam
| | - Thomas P Peacock
- Avian Viral Diseases programme, The Pirbright Institute, Woking, UK; St Mary's Campus, Imperial College London, London, UK
| | - Vu Thi Ngoc Bich
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - Thomas Fabrizio
- St Jude's Center for Excellence in Influenza Research and Surveillance, Memphis, TN, USA
| | - Dang Nguyen Hoang
- Division of Epidemiology, Department of Animal Health, Hanoi, Vietnam
| | - Nguyen Dang Tho
- MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), Centre de Recherche IRD, Montpellier, France
| | - Nguyen Thi Diep
- Division of Epidemiology, Department of Animal Health, Hanoi, Vietnam
| | - Minh Nguyen
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - Le Nguyen Minh Hoa
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - Hau Thi Thu Trang
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - Marc Choisy
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam; MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), Centre de Recherche IRD, Montpellier, France
| | - Ken Inui
- Food and Agriculture Organization of the United Nations, Hanoi, Vietnam
| | - Scott Newman
- Food and Agriculture Organization of the United Nations, Hanoi, Vietnam
| | | | - Rogier van Doorn
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Thanh Long To
- National Center for Veterinary Diagnostics, Department of Animal Health, Hanoi, Vietnam
| | - Munir Iqbal
- Avian Viral Diseases programme, The Pirbright Institute, Woking, UK
| | - Juliet E Bryant
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
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