Diversity of #Avian #Influenza A(#H5N6) Viruses in #WildBirds in Southern #China (J Gen Virol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

J Gen Virol. 2020 Jun 10. doi: 10.1099/jgv.0.001449. Online ahead of print.

Diversity of Avian Influenza A(H5N6) Viruses in Wild Birds in Southern China

Tao Zhang 1 2, Kai Fan 3, Xue Zhang 3, Yujuan Xu 3, Jian Xu 4, Bing Xu 1 2, Ruiyun Li 5

Affiliations: 1 Centre for Healthy Cities, Institute for China Sustainable Urbanization, Tsinghua University, Beijing, PR China. 2 Ministry of Education Key Laboratory for Earth System Modelling, Department of Earth System Science, Tsinghua University, Beijing, PR China. 3 College of Veterinary Medicine, China Agricultural University, Beijing, PR China. 4 School of Geography and Environmental Science, Ministry of Education’s Key Laboratory of Poyang Lake Wetland and Watershed Research, Jiangxi Normal University, Nanchang, Jiangxi, PR China. 5 MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK.

PMID: 32519938 DOI: 10.1099/jgv.0.001449



The predominance of H5N6 in ducks and continuous human cases have heightened its potential threat to public health in China. Therefore, the detection of emerging variants of H5N6 avian influenza viruses has become a priority for pandemic preparedness. Questions remain as to its origin and circulation within the wild bird reservoir and interactions at the wild-domestic interface. Samples were collected from migratory birds in Poyang Lake, Jiangxi Province, PR China during the routine bird ring survey in 2014-16. Phylogenetic and coalescent analyses were conducted to uncover the evolutionary relationship among viruses circulating in wild birds. Here, we report the potential origin and phylogenetic diversity of H5N6 viruses isolated from wild birds in Poyang Lake. Sequence analyses indicated that Jiangxi H5N6 viruses most likely evolved from Eurasian-derived H5Nx and H6N6 viruses through multiple reassortment events. Crucially, the diversity of the HA gene implies that these Jiangxi H5N6 viruses have diverged into two primary clades – clade and clade c. Phylogenetic analysis revealed two independent pathways of reassortment during 2014-16 that might have facilitated the generation of emerging variants within wild bird populations as well as inter-species infections. Our findings contribute to our understanding of the genetic diversification of H5N6 viruses in the wild bird population. These results highlight the necessity of large-scale surveillance of wild birds in the Poyang Lake area to address the threat of regional epizootic epidemics and attendant pandemics.

Keywords: Avian Influenza; H5N6; Reassortant strain; Wild Birds; China.


Regional #Transmission and #Reassortment of Highly Pathogenic #Avian #Influenza (HPAI) Viruses in #Bulgarian #Poultry 2017/18 (Viruses, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Viruses. 2020 Jun 1;12(6):E605. doi: 10.3390/v12060605.

Regional Transmission and Reassortment of Highly Pathogenic Avian Influenza (HPAI) Viruses in Bulgarian Poultry 2017/18

Divya Venkatesh 1, Adam Brouwer 2, Gabriela Goujgoulova 3, Richard Ellis 4, James Seekings 2 5, Ian H Brown 2, Nicola S Lewis 1 2

Affiliations: 1 Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, Hertfordshire AL9 7TA, UK. 2 OIE/FAO/ International Reference Laboratory for avian influenza, swine influenza and Newcastle Disease, Animal and Plant Health Agency (APHA), Weybridge, Addlestone, Surrey KT15 3NB, UK. 3 National Diagnostic Research Veterinary Medical Institute, 1231 Sofia, Bulgaria. 4 Surveillance and Laboratory Services Department, Animal and Plant Health Agency (APHA), Weybridge, Addlestone, Surrey KT15 3NB, UK. 5 Virology Department, Animal and Plant Health Agency (APHA), Weybridge, Addlestone, Surrey KT15 3NB, UK.

PMID: 32492965 DOI: 10.3390/v12060605



Between 2017 and 2018, several farms across Bulgaria reported outbreaks of H5 highly-pathogenic avian influenza (HPAI) viruses. In this study we used genomic and traditional epidemiological analyses to trace the origin and subsequent spread of these outbreaks within Bulgaria. Both methods indicate two separate incursions, one restricted to the northeastern region of Dobrich, and another largely restricted to Central and Eastern Bulgaria including places such as Plovdiv, Sliven and Stara Zagora, as well as one virus from the Western region of Vidin. Both outbreaks likely originate from different European virus ancestors circulating in 2017. The viruses were likely introduced by wild birds or poultry trade links in 2017 and have continued to circulate, but due to lack of contemporaneous sampling and sequences from wild bird viruses in Bulgaria, the precise route and timing of introduction cannot be determined. Analysis of whole genomes indicates a complete lack of reassortment in all segments but the matrix protein gene (MP), which presents as multiple smaller clusters associated with different European viruses. Ancestral reconstruction of host states of the hemagglutinin (HA) gene of viruses involved in the outbreaks suggests that transmission is driven by domestic ducks into galliform poultry. Thus, according to present evidence, we suggest the surveillance of domestic ducks as they are an epidemiologically relevant species for subclinical infection. Monitoring the spread due to movement between farms within regions and links to poultry production systems in European countries can help to predict and prevent future outbreaks. The lineage which caused the largest recorded poultry epidemic in Europe continues to circulate, and the risk of further transmission by wild birds during migration remains.

Keywords: Avian Influenza; H5; Reassortant strain; Poultry; Wild Birds; Bulgaria.


Detection of Low Pathogenic #Avian #Influenza Virus Subtype #H10N7 in #Poultry and #Environmental #Water Samples During a Clinical #Outbreak in Commercial Free-Range #Layers, #Netherlands 2017 (Front Vet Sci., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Front Vet Sci. 2020 May 5;7:237. doi: 10.3389/fvets.2020.00237. eCollection 2020.

Detection of Low Pathogenic Avian Influenza Virus Subtype H10N7 in Poultry and Environmental Water Samples During a Clinical Outbreak in Commercial Free-Range Layers, Netherlands 2017

Evelien A Germeraad 1, Armin R W Elbers 2, Naomi D de Bruijn 3, Rene Heutink 1, Wendy van Voorst 1 3, Renate Hakze-van der Honing 1, Saskia A Bergervoet 1, Marc Y Engelsma 1, Wim H M van der Poel 1, Nancy Beerens 1

Affiliations: 1 Wageningen Bioveterinary Research, Department of Virology, Lelystad, Netherlands. 2 Wageningen Bioveterinary Research, Department of Bacteriology and Epidemiology, Lelystad, Netherlands. 3 Poultry Department, GD-Animal Health, Deventer, Netherlands.

PMID: 32478107 PMCID: PMC7232570 DOI: 10.3389/fvets.2020.00237 Free PMC article



Wild birds are the natural reservoir of the avian influenza virus (AIV) and may transmit AIV to poultry via direct contact or indirectly through the environment. In the Netherlands, a clinically suspected free-range layer flock was reported to the veterinary authorities by the farmer. Increased mortality, a decreased feed intake, and a drop in egg production were observed. Subsequently, an infection with low pathogenic avian influenza virus was detected. This study describes the diagnostic procedures used for detection and subtyping of the virus. In addition to routine diagnostics, the potential of two different environmental diagnostic methods was investigated for detecting AIV in surface water. AIV was first detected using rRT-PCR and isolated from tracheal and cloacal swabs collected from the hens. The virus was subtyped as H10N7. Antibodies against the virus were detected in 28 of the 31 sera tested. An intravenous pathogenicity index (IVPI) experiment was performed, but no clinical signs (IVPI = 0) were observed. Post-mortem examination and histology confirmed the AIV infection. Multiple water samples were collected longitudinally from the free-range area and waterway near the farm. Both environmental diagnostic methods allowed the detection of the H10N7 virus, demonstrating the potential of these methods in detection of AIV. The described methods could be a useful additional procedure for AIV surveillance in water-rich areas with large concentrations of wild birds or in areas around poultry farms. In addition, these methods could be used as a tool to test if the environment or free-range area is virus-free again, at the end of an AIV epidemic.

Keywords: LPAIV; environmental sampling; outbreak; poultry; water.

Copyright © 2020 Germeraad, Elbers, de Bruijn, Heutink, van Voorst, Hakze-van der Honing, Bergervoet, Engelsma, van der Poel and Beerens.

Keywords: Avian Influenza; H10N7; Poultry; Wild Birds; Netherlands.


#Genotyping and #Reassortment #Analysis of Highly Pathogenic #Avian #Influenza Viruses #H5N8 and #H5N2 From #Egypt Reveals Successive Annual #Replacement of Genotypes (Infect Genet Evol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Infect Genet Evol. 2020 May 23;104375. doi: 10.1016/j.meegid.2020.104375. Online ahead of print.

Genotyping and Reassortment Analysis of Highly Pathogenic Avian Influenza Viruses H5N8 and H5N2 From Egypt Reveals Successive Annual Replacement of Genotypes

Kareem E Hassan 1, Noha Saad 2, Hassanein H Abozeid 3, Salama Shany 4, Magdy F El-Kady 4, Abdelsatar Arafa 2, Azza A A El-Sawah 4, Florian Pfaff 5, Hafez M Hafez 6, Martin Beer 5, Timm Harder 7

Affiliations: 1 Institute of Diagnostic Virology, Friedrich-Loeffler-Institute, Greifswald, Riems, Germany; Department of Poultry Diseases, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt. 2 National Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, 12618, Dokki, Giza, Egypt. 3 Department of Poultry Diseases, Faculty of Veterinary Medicine, Cairo University, Egypt. 4 Department of Poultry Diseases, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt. 5 Institute of Diagnostic Virology, Friedrich-Loeffler-Institute, Greifswald, Riems, Germany. 6 Institute of Poultry Diseases, Free University Berlin, Berlin, Germany. 7 Institute of Diagnostic Virology, Friedrich-Loeffler-Institute, Greifswald, Riems, Germany. Electronic address: Timm.Harder@fli.de.

PMID: 32454245 DOI: 10.1016/j.meegid.2020.104375



Highly pathogenic (HP) H5N1, clade 2.2.1, and low pathogenic avian influenza (LPAI) H9N2 viruses, G1-B lineage, are endemic in poultry in Egypt and have co-circulated for almost a decade. Surprisingly, no inter-subtypic reassortment events have been reported from the field during that time. After the introduction of HPAIV H5N8, clade, in Egyptian poultry in 2016, suddenly HP H5N2 reassortants with H9N2 viruses emerged. The current analyses focussed on studying 32 duck flocks, 4 broiler chicken flocks, and 1 turkey flock, suffering from respiratory manifestations with moderate to high mortality reared in two Egyptian governorates during 2019. Real-time RT-PCR substantiated the presence of HP H5N8 in 21 of the 37 investigated flocks with mixed infection of H9N2 in two of them. HP H5N1 was not detected. Full hemagglutinin (HA) sequencing of 10 samples with full-genome sequencing of three of them revealed presence of a single genotype. Very few substituting mutations in the HA protein were detected versus previous Egyptian HA sequences of that clade. Interestingly, amino acid substitutions in the Matrix (M2) and the Neuraminidase (NA) proteins associated with conferring both Amantadine and Oseltamivir resistance were present. Systematic reassortment analysis of all publicly available Egyptian whole genome sequences of HP H5N8 (n = 23), reassortant HP H5N2 (n = 2) and LP H9N2 (n = 53) viruses revealed presence of at least seven different genotypes of HPAI H5Nx viruses of clade in Egypt since 2016. For H9N2 viruses, at least three genotypes were distinguishable. Heat mapping and tanglegram analyses suggested that several internal gene segments in both HP H5Nx and H9N2 viruses originated from avian influenza viruses circulating in wild bird species in Egypt. Based on the limited set of whole genome sequences available, annual replacement patterns of HP H5Nx genotypes emerged and suggested selective advantages of certain genotypes since 2016.

Keywords: Beast analysis; Egypt; Genotyping; H5N2; H9N2; Highly pathogenic avian influenza; Phylogenetic analysis; Reassortment; Subtype H5N8; Tanglegram.

Copyright © 2019. Published by Elsevier B.V.

Conflict of interest statement. Declaration of Competing Interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Keywords: Avian Influenza; H5N2; H5N8; H9N2; Reassortant strain; Poultry; Wild Birds; Egypt; Antivirals; Drugs Resistance; Amantadine; Oseltamivir.


A Novel #Neuraminidase-Dependent #Hemagglutinin #Cleavage Mechanism Enables the Systemic #Spread of an #H7N6 #Avian #Influenza Virus (mBio, abstract)

[Source: mBio, full page: (LINK). Abstract, edited.]

mBio. 2019 Nov 5;10(6):e02369-19. doi: 10.1128/mBio.02369-19.

A Novel Neuraminidase-Dependent Hemagglutinin Cleavage Mechanism Enables the Systemic Spread of an H7N6 Avian Influenza Virus

Hyeok-Il Kwon 1 2, Young-Il Kim 1 2, Su-Jin Park 1 2, Eun-Ha Kim 1 2, Semi  Kim 1 2,  Young-Jae Si 1 2, Min-Suk Song 1 2, Philippe Noriel Q Pascua 1 3, Elena A Govorkova 3,  Robert G Webster 3, Richard J Webby 4, Young Ki Choi 5 2

Affiliations: 1 College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Republic of Korea. 2 Zoonotic Infectious Diseases Research Center, Chungbuk National University, Cheongju, Republic of Korea. 3 Division of Virology, Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA. 4 Division of Virology, Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA richard.webby@stjude.org choiki55@chungbuk.ac.kr. 5 College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, Republic of Korea richard.webby@stjude.org choiki55@chungbuk.ac.kr.

PMID: 31690675 PMCID: PMC6831776 DOI: 10.1128/mBio.02369-19



In this study, we demonstrate a novel mechanism for hemagglutinin (HA) activation in a naturally occurring H7N6 avian influenza A virus strain, A/mallard duck/Korea/6L/2007 (A/Mdk/6L/07). This novel mechanism allows for systemic infection of chickens, ducks, and mice, and A/Mdk/6L/07 can replicate in vitro without exogenous trypsin and exhibits broad tissue tropism in animals despite the presence of a monobasic HA cleavage motif (PEIPKGR/G). The trypsin-independent growth phenotype requires the N6 neuraminidase and the specific recognition of glycine at the P2 position of the HA cleavage motif by a thrombin-like protease. Correspondingly, viral growth is significantly attenuated by the addition of a thrombin-like protease inhibitor (argatroban). These data provide evidence for a previously unrecognized virus replication mechanism and support the hypothesis that thrombin-mediated HA cleavage is an important virulence marker and potential therapeutic target for H7 influenza viruses.



The identification of virulence markers in influenza viruses underpins risk assessment programs and the development of novel therapeutics. The cleavage of the influenza virus HA is a required step in the viral life cycle, and phenotypic differences in viruses can be caused by changes in this process. Here, we describe a novel mechanism for HA cleavage in an H7N6 influenza virus isolated from a mallard duck. The mechanism requires the N6 protein and full activity of thrombin-like proteases and allows the virus to cause systemic infection in chickens, ducks, and mice. The thrombin-mediated cleavage of HA is thus a novel virulence determinant of avian influenza viruses.

Keywords: GRG motif; H7; N6 neuraminidase; influenza; pathogenicity; thrombin-like protease; trypsin-independent growth; virulence.

Copyright © 2019 Kwon et al.

Keywords: Avian Influenza; H7N6; Wild Birds; Viral pathogenesis.


#Phylogeography of Highly Pathogenic #H5 #Avian #Influenza Viruses in #China (Virol Sin., abstract)

[Source: Virologica Sinica, full page: (LINK). Abstract, edited.]

Phylogeography of Highly Pathogenic H5 Avian Influenza Viruses in China

Xiaowen Li, Xueying Li & Bing Xu

Virologica Sinica (2020)



The spread of H5 highly pathogenic avian influenza viruses poses serious threats to the poultry industry, wild bird ecology and human health. Circulation of H5 viruses between poultry and wild birds is a significant public health threat in China. Thus, viral migration networks in this region need to be urgently studied. Here, we conducted molecular genetic analyses of the hemagglutinin genes of H5 highly pathogenic avian influenza viruses in multiple hosts from 2000 to 2018 in China. Our aim was to clarify the roles of different hosts in the evolution of H5 viruses. We used a flexible Bayesian statistical framework to simulate viral space diffusion and continuous-time Markov chains to infer the dynamic evolutionary process of spatiotemporal dissemination. Bayesian phylogeographic analysis of H5 viruses showed for the first time that H5 viruses in poultry and wild birds were present in Guangdong Province. Furthermore, Guangdong, Jiangsu, Shanghai and Hunan acted as the epicenters for the spread of various H5 subtypes viruses in poultry, and Henan, Shanghai, Hong Kong and Inner Mongolia acted as epicenters for the spread of various H5 subtypes viruses in wild birds. Thus, H5 viruses exhibited distinct evolutionary dynamics in poultry and wild birds. Our findings extend our understanding of the transmission and spread of highly pathogenic H5 avian influenza viruses in China.

Keywords: Avian Influenza; H5; Poultry; Wild birds; China.


Co-circulation of Multiple #Reassortant #H6 Subtype #Avian #Influenza Viruses in #WildBirds in Eastern #China, 2016-2017 (Virol J., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Virol J. 2020 Apr 29;17(1):62. doi: 10.1186/s12985-020-01331-z.

Co-circulation of Multiple Reassortant H6 Subtype Avian Influenza Viruses in Wild Birds in Eastern China, 2016-2017

Chuanxia Hu 1, Xiaofang Li 1, Caihui Zhu 1, Feng Zhou 2, Wangjun Tang 1, Di Wu 3, Zhihui Li 1, Lichen Zhou 4, Jing Liu 1, Xiaoman Wei 5 6 7, Jie Cui 5 6, Tianhou Wang 8 9, Guimei He 10 11

Affiliations: 1 School of Life Sciences, East China Normal University, Shanghai, China. 2 Jinshan Forest Working-Station, Shanghai, China. 3 Shanghai Wildlife Conservation and Management Center, Shanghai, China. 4 Shanghai Zoo, Shanghai, China. 5 Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China. 6 Unit of Pathogen Bioinformatics, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, 200031, China.  7 University of Chinese Academy of Sciences, Beijing, China. 8 School of Life Sciences, East  China Normal University, Shanghai, China. Thwang@bio.ecnu.edu.cn. 9 Institute of Eco-Chongming (IEC), East China Normal University, Shanghai, China. Thwang@bio.ecnu.edu.cn. 10 School of Life Sciences, East China Normal University, Shanghai, China. gmhe@bio.ecnu.edu.cn. 11 Institute of Eco-Chongming (IEC), East China Normal University, Shanghai, China. gmhe@bio.ecnu.edu.cn.

PMID: 32349760 DOI: 10.1186/s12985-020-01331-z




H6 subtype influenza viruses were prevalent in domestic poultry and wild birds, which also could pose potential threat to humans. However, little is known about the prevalence of H6 subtype viruses in wild birds in eastern China, a crucial stopover or wintering site for migratory wild birds along the East Asian-Australasian Flyway.


During the routine surveillance in 2016-2017, H6 subtype AIVs positive samples were identified, and the representative strains were selected for further sequence and phylogenetic analysis and the pathogenicity in mice were evaluated.


Among the 30 H6 positive samples, there were at least four subtypes H6N1, H6N2, H6N5 and H6N8 co-circulated in Shanghai, China. Genetic analysis showed the 8 representative isolates shared homology with different AIV sub-lineages isolated from domestic ducks or wild birds in different countries along the East Asian-Australasian flyways, and were classified into 7 new genotypes. The pathogenicity to mice showed that these H6 viruses could replicate efficiently in the lungs without prior adaptation, but could not cause mice death.


Eight novel strains belonged to H6N1, H6N2, H6N5 and H6N8 subtypes were isolated. Phylogenetic analyses revealed multiple origins of internal genes indicative of robust reassortment events and frequent wild birds-poultry interaction encouraging the evolution and emergence of new genotypes. The pathogenicity to mammals should be closely monitored to prevent the emergence of novel pandemic viruses.

Keywords: Eastern China; H6 subtype avian influenza virus; Novel; Reassortant; Shanghai; Wild birds.

Keywords: Avian Influenza; H6N1; H6N2; H6N5; H6N8; Reassortant strain; Wild Birds; China.


Highly Pathogenic #H5N6 #Avian #Influenza Virus Subtype Clade Indigenous in South #Korea (Sci Rep., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Sci Rep. 2020 Apr 29;10(1):7241. doi: 10.1038/s41598-020-64125-x.

Highly Pathogenic H5N6 Avian Influenza Virus Subtype Clade Indigenous in South Korea

Juyoun Shin 1, Shinseok Kang 2, Hyeonseop Byeon 2, Sung-Min Cho 3, Seon-Yeong Kim 3, Yeun-Jun Chung 1 3, Seung-Hyun Jung 4 5

Affiliations: 1 Department of Microbiology, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. 2 Chungbuk Veterinary Service Laboratory, Chungju, Republic of Korea. 3 Integrated Research Center for Genome Polymorphism, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. 4 Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. hyun@catholic.ac.kr. 5 Cancer Evolution Research Center, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. hyun@catholic.ac.kr.

PMID: 32350323 DOI: 10.1038/s41598-020-64125-x



The outbreaks of the highly pathogenic avian influenza (HPAI) in 2016-2017 and 2017-2018, caused by novel reassortant clade H5N6 viruses, resulted in the loss of one billion birds in South Korea. Here, we characterized the H5N6 viruses isolated from wild birds in South Korea from December 2017 to August 2019 by next-generation sequencing. The results indicated that clade H5N6 viruses isolated in 2017 and 2019 shared almost identical nucleotide sequences with the HPAI H5N6 viruses from 2016 in South Korea. This repeated detection of evolutionarily identical H5N6 viruses in same region for more than three years may suggest indigenization of the HPAI H5N6 virus in South Korea. Phylogenetic analysis demonstrated that the clade H5N6 viruses isolated in 2017 and 2019 were evolutionarily distinct from those isolated in 2018. Molecular analysis revealed that the H5N6 viruses isolated in 2017 and 2019 had features associated with an increased risk of human infection (e.g. a deletion at position 133 of HA and glutamic acid residue at position 92 of NS1). Overall, these genomic features of HPAI H5N6 viruses highlight the need for continuous monitoring of avian influenza viruses in wild migratory birds as well as in domestic birds.

Keywords: Avian Influenza; H5N6; Poultry; Wild Birds; S. Korea.


#Phylogeography and #antigenic #diversity of low pathogenic #avian #influenza #H13 and #H16 viruses (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

Phylogeography and antigenic diversity of low pathogenic avian influenza H13 and H16 viruses

Josanne H. Verhagen, Marjolein Poen, David E. Stallknecht, Stefan van der Vliet, Pascal Lexmond, Srinand Sreevatsan, Rebecca L. Poulson, Ron A.M. Fouchier, Camille Lebarbenchon

DOI: 10.1128/JVI.00537-20



Low pathogenic avian influenza viruses (LPAIVs) are genetically highly variable and have diversified into multiple evolutionary lineages that are primarily associated with wild bird reservoirs. Antigenic variation has been described for mammalian influenza viruses and for highly pathogenic avian influenza viruses that circulate in poultry, but much less is known about antigenic variation of LPAIVs. In this study, we focussed on H13 and H16 LPAIVs that circulate globally in gulls. We investigated the evolutionary history and intercontinental gene flow based on the hemagglutinin (HA) gene and used representative viruses from genetically distinct lineages to determine their antigenic properties by hemagglutination inhibition assays. For H13 at least three distinct genetic clades were evident, while for H16 at least two distinct genetic clades were evident. Twenty and ten events of intercontinental gene flow were identified for H13 and for H16 viruses, respectively. At least two antigenic variants of H13 and at least one antigenic variant of H16 were identified. Amino acid positions in the HA protein that may be involved in the antigenic variation were inferred, and some of the positions were located near the receptor binding site of the HA protein, as they are in the HA protein of mammalian influenza A viruses. These findings suggest independent circulation of H13 and H16 subtypes in gull populations as antigenic patterns do not overlap and contribute to the understanding of the genetic and antigenic variation of LPAIV naturally circulating in wild birds.



Wild birds play a major role in the epidemiology of low pathogenic avian influenza viruses (LPAIVs) from which these viruses are occasionally transmitted—directly or indirectly—to other species, including domestic animals, wild mammals and humans, where they can cause subclinical to fatal disease. Despite a multitude of genetic studies, the antigenic variation of LPAIVs in wild birds is poorly understood. Here, we investigated the evolutionary history, intercontinental gene flow, and the antigenic variation among H13 and H16 LPAIVs. The circulation of the subtypes H13 and H16 seems to be maintained by a narrower host range, in particular gulls, than for the majority of LPAIV subtypes and may therefore serve as a model for evolution and epidemiology of H1-H12 LPAIVs in wild birds. The findings suggest that H13 and H16 LPAIVs circulate independently of each other and emphasize the need to investigate within clade antigenic variation of LPAIVs in wild birds.

Copyright © 2020 Verhagen et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.

Keywords: Avian Influenza; H13; H16; Wild Birds.


Characteristics of the First #H16N3 Subtype #Influenza A Viruses Isolated in Western #China (Transbound Emerg Dis., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Transbound Emerg Dis 2020 Apr 7 [Online ahead of print]

Characteristics of the First H16N3 Subtype Influenza A Viruses Isolated in Western China

Yulei Li 1, Minghui Li 1, Jingman Tian 1, Yaping Zhang 1, Xiaoli Bai 1, Xiaoliang Wang 2, Jianzhong Shi 1, Yumei Wang 2, Long Ma 2, Cen Yang 1, Yanbing Li 1

Affiliations: 1 State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China. 2 Preventive and Control Center for Animal Disease of Ningxia Hui Autonomous Region, Yinchuan, China.

PMID: 32266788 DOI: 10.1111/tbed.13511



The first documented avian influenza virus subtype H16N3 was isolated in 1975 and is currently detectable in many countries worldwide. However, the prevalence, biological characteristics and threat to humans of the avian influenza virus H16N3 subtype in China remain poorly understood. We performed avian influenza surveillance in major wild bird gatherings across the country from 2017 to 2019, resulting in the isolation of two H16N3 subtype influenza viruses. Phylogenetic analysis showed these viruses belong to the Eurasian lineage, and both viruses presented the characteristics of inter-species reassortment. In addition, the two viruses exhibited limited growth capacity in MDCK and A549 cells. Receptor-binding assays indicated that the two H16N3 viruses presented dual receptor-binding profiles, being able to bind to both human and avian-type receptors, where GBHG/NX/2/2018(H16N3) preferentially bound the avian-type receptor, while GBHG/NX/1/2018(H16N3) showed greater binding to the human-type receptor, even the mice virulence data showed the negative results. Segments from other species have been introduced into the H16N3 avian influenza virus, which may alter its pathogenicity and host tropism, potentially posing a threat to animal and human health in the future. Consequently, it is necessary to increase monitoring of the emergence and spread of avian influenza subtype H16N3 in wild birds.

Keywords: H16N3; avian influenza virus; evolution; reassortant.

© 2020 The Authors. Transboundary and Emerging Diseases published by Blackwell Verlag GmbH.

Keywords: Avian Influenza; H16N3; Reassortant strain; Wild Birds; China.