#H5N8 and #H7N9 packaging signals constrain #HA #reassortment with a seasonal #H3N2 #influenza A virus (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

H5N8 and H7N9 packaging signals constrain HA reassortment with a seasonal H3N2 influenza A virus

Maria C. White, Hui Tao, John Steel, and Anice C. Lowen

PNAS published ahead of print February 13, 2019 / DOI: https://doi.org/10.1073/pnas.1818494116

Edited by Peter Palese, Icahn School of Medicine at Mount Sinai, New York, NY, and approved January 17, 2019 (received for review October 26, 2018)



Influenza A viruses (IAV) can exchange genetic material in coinfected cells in a process termed reassortment. The last three IAV pandemic strains arose from reassortment events involving human and nonhuman IAVs. Because introduction of the hemagglutinin (HA) gene from a nonhuman virus is required for a pandemic, we addressed the compatibility of human and avian IAV. We show that sequence differences between human and avian HA genes limit the potential for reassortment. However, human IAV still incorporated heterologous HA genes at a low level in coinfected animals. This observed low level of incorporation could become significant if reassortant viruses had a fitness advantage within the host, such as resistance to preexisting immunity, and highlights the continued need for IAV surveillance.



Influenza A virus (IAV) has a segmented genome, which (i) allows for exchange of gene segments in coinfected cells, termed reassortment, and (ii) necessitates a selective packaging mechanism to ensure incorporation of a complete set of segments into virus particles. Packaging signals serve as segment identifiers and enable segment-specific packaging. We have previously shown that packaging signals limit reassortment between heterologous IAV strains in a segment-dependent manner. Here, we evaluated the extent to which packaging signals prevent reassortment events that would raise concern for pandemic emergence. Specifically, we tested the compatibility of hemagglutinin (HA) packaging signals from H5N8 and H7N9 avian IAVs with a human seasonal H3N2 IAV. By evaluating reassortment outcomes, we demonstrate that HA segments carrying H5 or H7 packaging signals are significantly disfavored for incorporation into a human H3N2 virus in both cell culture and a guinea pig model. However, incorporation of the heterologous HAs was not excluded fully, and variants with heterologous HA packaging signals were detected at low levels in vivo, including in naïve contact animals. This work indicates that the likelihood of reassortment between human seasonal IAV and avian IAV is reduced by divergence in the RNA packaging signals of the HA segment. These findings offer important insight into the molecular mechanisms governing IAV emergence and inform efforts to estimate the risks posed by H7N9 and H5N8 subtype avian IAVs.

influenza A virus – reassortment – packaging – zoonosis – antigenic shift

Keywords: Influenza A; Pandemic Influenza; Seasonal Influenza; Avian Influenza; Reassortant strain; H3N2; H5N8; H7N9; Animal models.



#Shedding of clade #H5N8 and #H5N2 highly pathogenic #avian #influenza viruses in peridomestic #wildbirds in the #US (Transbound Emerg Dis., abstract)

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

Transbound Emerg Dis. 2019 Feb 10. doi: 10.1111/tbed.13147. [Epub ahead of print]

Shedding of clade H5N8 and H5N2 highly pathogenic avian influenza viruses in peridomestic wild birds in the U.S.

Bosco-Lauth AM1, Marlenee NL1, Hartwig AE1, Bowen RA1, Root JJ2.

Author information: 1 Colorado State University, Fort Collins, CO, USA. 2 United States Department of Agriculture, National Wildlife Research Center, Fort Collins, CO, USA.



European starlings (Sturnus vulgaris), house sparrows (Passer domesticus) and rock pigeons (Columba livia) are all wild birds commonly found in large numbers in and around human dwellings and domestic livestock operations. This study evaluated the susceptibility of these species to three strains of highly pathogenic avian influenza virus (HP AIV) clade isolated in the US. Experimental infection of European starlings and rock pigeons did not result in any overt signs attributable to AIV infection and no virus shedding was detected from the oral and cloacal routes. House sparrows shed by the oral route and exhibited limited mortality. Individuals from all three species seroconverted following infection. These data suggest that none of these birds are a likely potential bridge host for future HP AIV outbreaks but that their seroconversion may be a useful surveillance tool for detection of circulating H5 HP AIV.

This article is protected by copyright. All rights reserved.

KEYWORDS: Columba livia ; Passer domesticus ; Sturnus vulgaris ; Avian influenza virus; Biosecurity; Clade; European starling; Experimental infection; H5N2; H5N8; Highly pathogenic; House sparrow; Outbreak; Rock pigeon

PMID: 30740920 DOI: 10.1111/tbed.13147

Keywords: Avian Influenza; H5N2; H5N8; Wild Birds; USA.


Experimental #infection of racing #pigeons (Columba livia domestica) with highly pathogenic Clade sub-group B #H5N8 #avian #influenza virus (Vet Microbiol., abstract)

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

Vet Microbiol. 2018 Dec;227:127-132. doi: 10.1016/j.vetmic.2018.10.028. Epub 2018 Nov 2.

Experimental infection of racing pigeons (Columba livia domestica) with highly pathogenic Clade sub-group B H5N8 avian influenza virus.

Abolnik C1, Stutchbury S2, Hartman MJ3.

Author information: 1 Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, 0110, South Africa. Electronic address: celia.abolnik@up.ac.za. 2 Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, 0110, South Africa. 3 Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.



Reported mass mortalities in wild pigeons and doves during the 2017/2018 Clade HPAI H5N8 outbreaks in South Africa necessitated an investigation of healthy racing pigeons for their susceptibility and ability to transmit a Clade sub-group B virus of South African origin. Pigeons challenged with medium (104.5 EID50) and high doses (106 EID50) but not a low dose (103 EID50) of virus, shed virus in low levels of <103 EID50/ml from the oropharynx and cloaca for up to eight days, with peak shedding around 4 days post challenge. Challenged pigeons were able to transmit the virus to contact pigeons, but not contact chickens. Neither pigeons nor chickens presented clinical disease, and only two pigeons in the group that received the high challenge dose developed influenza A-virus specific antibodies. The levels of virus shed by the racing pigeons were well below the published bird infectious dose 50 values for most poultry, especially chickens, therefore the risk that racing pigeons could act as propagators and disseminators through excretion of Clade HPAI H5N8 strains remains negligible.

Copyright © 2018 Elsevier B.V. All rights reserved.

KEYWORDS: Chickens; Clade; Highly pathogenic avian influenza; Pigeons

PMID: 30473343 DOI: 10.1016/j.vetmic.2018.10.028 [Indexed for MEDLINE]

Keywords: Avian Influenza; H5N8; Poultry; South Africa.


Co-infections, genetic, and #antigenic relatedness of #avian #influenza #H5N8 and #H5N1 viruses in domestic and #wildbirds in #Egypt (Poult Sci., abstract)

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

Poult Sci. 2019 Jan 22. doi: 10.3382/ps/pez011. [Epub ahead of print]

Co-infections, genetic, and antigenic relatedness of avian influenza H5N8 and H5N1 viruses in domestic and wild birds in Egypt.

Shehata AA1, Sedeik ME2, Elbestawy AR3, Zain El-Abideen MA4, Ibrahim HH5, Kilany WH4, Ali A6.

Author information: 1 Avian and Rabbit Diseases Department, Faculty of Veterinary Medicine, University of Sadat City, Egypt. 2 Department of Poultry and Fish Diseases, Faculty of Veterinary Medicine, Alexandria University, Alexandria, Egypt. 3 Poultry Diseases Department, Faculty of Veterinary medicine, Damanhur University, Behaira, Egypt. 4 Veterinary Quality Control on Poultry Production (RLQP), Animal Health Research Institute (AHRI), Dokki, Giza, Egypt. 5 Poultry Diseases Department, Faculty of Veterinary Medicine, Aswan University, Aswan, Egypt. 6 Poultry Diseases Department, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt.



A total of 50 poultry farms of commercial broilers (N = 39) and commercial layers (N = 11) suffered from respiratory problems and mortality during the period from January 2016 to December 2017 were investigated. Also, samples were collected from quail (N = 4), Bluebird (Sialis, N = 1), and Greenfinch (Chloris chloris, N = 1) for analysis. Respiratory viral pathogens were screened by PCR and positive samples were subjected to virus isolation and genetic identification. Antigenic relatedness of isolated avian influenza (AI) H5 subtype was evaluated using cross-hemagglutination inhibition. Results revealed that the incidence of single virus infections in commercial broilers was 64.1% (25/39), with the highest incidence for ND (33.3%) and H9N2 (20.5%), followed by H5N1 (7.7%) and H5N8 (2.7). Meanwhile, H9N2/ND mixed infection was the most observed case (7.7%). Other mixed infections H5N1/ND, H5N1/H9N2/ND, H5N1/H9N2/ND/IB, H9N2/IB, and H9N2/ILT were also observed (2.6% each). In commercial layers, H5N1 and ILT were the only detected single infections (18.1% each). Mixed H9N2/ND was the most predominant infection in layers (27.3%). Other mixed infections of H9N2/IB, H5N1/H5N8/H9N2, and H9N2/ND/IB were observed in 3 separate farms (9.1% each). The H5N8 virus was detected in one quail farm and 2 out of 3 wild bird’s samples. Partial HA gene sequence analysis showed the clustering of the selected AI H5N8 within the clade, while H5N1 clustered with the clade Interestingly, the H5N8 isolated from chickens possessed 6 amino acids substitutions at HA1 compared to those isolated from wild birds with low antigenic relatedness to AI H5N1 clades 2.2.1 or In conclusion, mixed viral infections were observed in both broiler and layer chickens in Egypt. The detected triple H5N1, H9N2, and H5N8 influenza co-infection raises the concern of potential AI epidemic strain emergence. The low genetic and antigenic relatedness between AI H5N1 and H5N8 viruses suggest the need for modification of vaccination strategies of avian influenza in Egypt along with strict biosecurity measures.

PMID:  30668795 DOI: 10.3382/ps/pez011

Keywords: Avian Influenza; H5N1; H5N8; H9N2; Poultry; Wild Birds; Egypt.


Role of #Backyard #Flocks in Transmission Dynamics of Highly Pathogenic #Avian #Influenza A(#H5N8) Clade, #France, 2016–2017 (Emerg Infect Dis., abstract)

[Source: US Centers for Disease Control and Prevention (CDC), Emerging Infectious Diseases Journal, full page: (LINK). Abstract, edited.]

Volume 25, Number 3—March 2019 / Dispatch

Role of Backyard Flocks in Transmission Dynamics of Highly Pathogenic Avian Influenza A(H5N8) Clade, France, 2016–2017

Marie Souvestre, Claire Guinat, Eric Niqueux, Luc Robertet, Guillaume Croville, Mathilde Paul, Audrey Schmitz, Anne Bronner, Nicolas Eterradossi, and Jean-Luc Guérin

Author affiliations: Ecole Nationale Vétérinaire, Institut National de la Recherche Agronomique, Université de Toulouse, Toulouse, France (M. Souvestre, C. Guinat, L. Robertet, G. Croville, M. Paul, J.-L. Guérin); Agence Nationale de Sécurité Sanitaire, Ploufragan, France (E. Niqueux, A. Schmitz, N. Eterradossi); Direction Générale de l’Alimentation, Paris, France (A. Bronner)



Highly pathogenic avian influenza A(H5N8) clade spread in France during 2016–2017. We assessed the biosecurity and avian influenza virus infection status of 70 backyard flocks near H5N8-infected commercial farms. One flock was seropositive for clade Backyard flocks linked to commercial farms had elevated risk for H5 infection.

Keywords: Avian Influenza; H5N8; Poultry; France.


Efficacy of a Recombinant Turkey Herpesvirus AI (#H5) #Vaccine in Preventing Transmission of Heterologous Highly Pathogenic #H5N8 Clade Challenge Virus in Commercial #Broilers and Layer Pullets (J Immunol Res., abstract)

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

J Immunol Res. 2018 Nov 21;2018:3143189. doi: 10.1155/2018/3143189. eCollection 2018.

Efficacy of a Recombinant Turkey Herpesvirus AI (H5) Vaccine in Preventing Transmission of Heterologous Highly Pathogenic H5N8 Clade Challenge Virus in Commercial Broilers and Layer Pullets.

Palya V1, Tatár-Kis T1, Walkóné Kovács E1, Kiss I1, Homonnay Z1, Gardin Y2, Kertész K3, Dán Á4.

Author information: 1 Scientific Support and Investigation Unit, Ceva-Phylaxia, Ceva Animal Health, Budapest 1107, Hungary. 2 Ceva Animal Health, Libourne 33500, France. 3 Ceva-Phylaxia, Ceva Animal Health, Budapest 1107, Hungary. 4 Veterinary Diagnostic Directorate, National Food Chain Safety Office (NEBIH), Budapest 1149, Hungary.



Outbreaks caused by the highly pathogenic avian influenza virus (HPAIV) H5N8 subtype clade were first reported in 2014 in South Korea then spread very rapidly in Asia, to Europe, and for the first time, to North America. Efficacy of a recombinant HVT-AI (H5) vaccine (rHVT-H5) to provide clinical protection as well as to significantly reduce the shedding of an H5N8 challenge virus has already been demonstrated in SPF chickens. The aim of our studies was to test the efficacy of the same rHVT-H5 vaccine in controlling the transmission of a recent Hungarian HPAIV H5N8 challenge virus in commercial chickens. Broilers and layers were vaccinated at day old according to the manufacturer’s recommendation and then challenged with a 2017 Hungarian HPAIV H5N8 ( isolate at 5 or 7 weeks of age, respectively. Evaluation of clinical protection, reduction of challenge virus shedding, and transmission to vaccinated contact birds was done on the basis of clinical signs/mortality, detection, and quantitation of challenge virus in oronasal and cloacal swabs (regularly between 1 and 14 days postchallenge). Measurement of seroconversion to AIV nucleoprotein was used as an indicator of infection and replication of challenge virus. Our results demonstrated that rHVT-H5 vaccination could prevent the development of clinical disease and suppress shedding very efficiently, resulting in the lack of challenge virus transmission to vaccinated contact chickens, regardless the type of birds. Single immunization with the tested rHVT-H5 vaccine proved to be effective to stop HPAIV H5N8 ( transmission within vaccinated poultry population under experimental conditions.

PMID: 30584541 PMCID: PMC6280313 DOI: 10.1155/2018/3143189

Keywords: Avian Influenza; H5N8; Poultry; Vaccines.


Integration of #genetic and #epidemiological data to infer #H5N8 HPAI virus #transmission dynamics during the 2016-2017 #epidemic in #Italy (Sci Rep., abstract)

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

Sci Rep. 2018 Dec 21;8(1):18037. doi: 10.1038/s41598-018-36892-1.

Integration of genetic and epidemiological data to infer H5N8 HPAI virus transmission dynamics during the 2016-2017 epidemic in Italy.

Mulatti P1, Fusaro A2, Scolamacchia F2, Zecchin B2, Azzolini A2, Zamperin G2, Terregino C2, Cunial G2, Monne I2, Marangon S2.

Author information: 1 Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, (Padua), Italy. pmulatti@izsvenezie.it. 2 Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, (Padua), Italy.



Between October 2016 and December 2017, several European Countries had been involved in a massive Highly Pathogenic Avian Influenza (HPAI) epidemic sustained by H5N8 subtype virus. Starting on December 2016, also Italy was affected by H5N8 HPAI virus, with cases occurring in two epidemic waves: the first between December 2016 and May 2017, and the second in July-December 2017. Eighty-three outbreaks were recorded in poultry, 67 of which (80.72%) occurring in the second wave. A total of 14 cases were reported in wild birds. Epidemiological information and genetic analyses were conjointly used to get insight on the spread dynamics. Analyses indicated multiple introductions from wild birds to the poultry sector in the first epidemic wave, and noteworthy lateral spread from October 2017 in a limited geographical area with high poultry densities. Turkeys, layers and backyards were the mainly affected types of poultry production. Two genetic sub-groups were detected in the second wave in non-overlapping geographical areas, leading to speculate on the involvement of different wild bird populations. The integration of epidemiological data and genetic analyses allowed to unravel the transmission dynamics of H5N8 virus in Italy, and could be exploited to timely support in implementing tailored control measures.

PMID: 30575785 DOI: 10.1038/s41598-018-36892-1

Keywords: Avian Influenza; H5N8; Poultry; Wild Birds; Italy.