Molecular characterization of H9N2 avian influenza viruses isolated from vaccinated broiler chickens in northeast Iran

Bahari, P; Pourbakhsh, Seyed Ali; Shoushtari, Hamid; Bahmaninejad, Mohammad Ali

doi:10.1007/s11250-015-0848-x

Cited by 20 publications

(21 citation statements)

References 24 publications

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“…Mutations in the HA glycoprotein are known to be particularly influential on modulating the overlapping and interrelated properties of receptor specificity, host and tissue tropism, pathogenicity, and antigenicity (32, 43, 50). Conventional avian influenza vaccines typically lose efficacy as HAs undergo antigenic drift, and several research groups have suggested that the widespread use of poultry vaccines may even contribute to driving antigenic drift (21, 22, 24, 51, 52). Recently, we generated a panel of “antigenic drift-like” escape mutants (through in vitro selection with MAbs), some of which contained deletions within the 220 loop region of the HA RBS (34).…”

Section: Discussionmentioning

confidence: 99%

“…Classical inactivated vaccines have been widely utilized in poultry in many areas to attempt to curb economic losses associated with H9N2 infection (8, 21–24). Veterinary influenza vaccines face challenges similar to those of human seasonal influenza vaccines in terms of requiring continual evaluation and updating due to virus antigenic drift.…”

Section: Introductionmentioning

confidence: 99%

“…Veterinary influenza vaccines face challenges similar to those of human seasonal influenza vaccines in terms of requiring continual evaluation and updating due to virus antigenic drift. To date, there are limited field data assessing the efficacy of currently licensed H9N2 vaccines, and epidemiological studies suggest that enzootic transmission may continue even in regions with large numbers of vaccinated flocks (21, 22, 24). …”

Section: Introductionmentioning

confidence: 99%

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Immune Escape Variants of H9N2 Influenza Viruses Containing Deletions at the Hemagglutinin Receptor Binding Site Retain Fitness In Vivo and Display Enhanced Zoonotic Characteristics

Peacock

Benton

James

et al. 2017

J Virol

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H9N2 avian influenza viruses are enzootic in poultry across Asia and North Africa, where they pose a threat to human health as both zoonotic agents and potential pandemic candidates. Poultry vaccination against H9N2 viruses has been employed in many regions; however, vaccine effectiveness is frequently compromised due to antigenic drift arising from amino acid substitutions in the major influenza virus antigen hemagglutinin (HA). Using selection with HA-specific monoclonal antibodies, we previously identified H9N2 antibody escape mutants that contained deletions of amino acids in the 220 loop of the HA receptor binding sites (RBSs). Here we analyzed the impact of these deletions on virus zoonotic infection characteristics and fitness. We demonstrated that mutant viruses with RBS deletions are able to escape polyclonal antiserum binding and are able to infect and be transmitted between chickens. We showed that the deletion mutants have increased binding to human-like receptors and greater replication in primary human airway cells; however, the mutant HAs also displayed reduced pH and thermal stability. In summary, we infer that variant influenza viruses with deletions in the 220 loop could arise in the field due to immune selection pressure; however, due to reduced HA stability, we conclude that these viruses are unlikely to be transmitted from human to human by the airborne route, a prerequisite for pandemic emergence. Our findings underscore the complex interplay between antigenic drift and viral fitness for avian influenza viruses as well as the challenges of predicting which viral variants may pose the greatest threats for zoonotic and pandemic emergence.IMPORTANCE Avian influenza viruses, such as H9N2, cause disease in poultry as well as occasionally infecting humans and are therefore considered viruses with pandemic potential. Many countries have introduced vaccination of poultry to try to control the disease burden; however, influenza viruses are able to rapidly evolve to escape immune pressure in a process known as “antigenic drift.” Previously, we experimentally generated antigenic-drift variants in the laboratory, and here, we test our “drifted” viruses to assess their zoonotic infection characteristics and transmissibility in chickens. We found that the drifted viruses were able to infect and be transmitted between chickens and showed increased binding to human-like receptors. However, the drift mutant viruses displayed reduced stability, and we predict that they are unlikely to be transmitted from human to human and cause an influenza pandemic. These results demonstrate the complex relationship between antigenic drift and the potential of avian influenza viruses to infect humans.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Immune Escape Variants of H9N2 Influenza Viruses Containing Deletions at the Hemagglutinin Receptor Binding Site Retain Fitness In Vivo and Display Enhanced Zoonotic Characteristics

Peacock

Benton

James

et al. 2017

J Virol

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“…Due to the economic damage caused by enzootic H9N2, many countries including China, Israel, South Korea, Morocco, Pakistan, Egypt and Iran have adopted vaccination at either a national or local level as a key approach for preventing H9N2 disease in poultry [28,36,44,[178][179][180][181].…”

Section: Vaccination and Controlmentioning

confidence: 99%

“…Therefore, in many regions H9N2 viruses continue to infect and cause disease in vaccinated poultry with tentative evidence suggesting that sub-optimal use of vaccination may be driving antigenic drift and/or clade replacement, and theoretically zoonotic potential and pathogenesis [27,28,41,73,86,181,182]. Because of this there is a real need for i) better understanding of the molecular determinants of H9 antigenicity, ii) better understanding of antigenic drift and the consequences upon viral fitness and zoonotic potential and iii) next generation vaccines that protect better against multiple strains and antigenically drifted variants.…”

Section: Vaccination and Controlmentioning

confidence: 99%

A Global Perspective on H9N2 Avian Influenza Virus

Peacock¹,

James²,

Sealy³

et al. 2019

Preprint

113

123

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H9N2 avian influenza viruses have become globally widespread in poultry over the last two decades and represent a genuine threat both to the global poultry industry but also humans through their high rates of zoonotic infection and pandemic potential. H9N2 viruses are generally hyperendemic in effected countries and have been found in poultry in many new regions in recent years. In this review we examine the current global spread of H9N2 avian influenza viruses as well as their host range, tropism, transmission routes and the risk posed by these viruses to human health.

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Mutation signature in neuraminidase gene of avian influenza H9N2/G1 in Egypt

Mosaad¹,

Arafa²,

Hussein

et al. 2017

VirusDis.

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The low pathogenic avian influenza (LPAI) H9N2 subtype has become the most prevalent and widespread in many Asian and Middle Eastern countries. It causes an enzootic situation in commercial poultry and known as a potential facilitator virus that can be transmitted to human from birds. The neuraminidase (NA) gene plays an important role the release and spread of the virus from infected cells and throughout the bird. The complete nucleotide sequences of the NA gene of seven H9N2 viruses collected from apparent healthy chicken and quail flocks in Egypt during 2014-2015, were amplified and sequenced. The phylogenetic relationships were investigated and all viruses were belonging to the A/Q/HK/G1/97 strain (G1-like). There were no insertions or deletions or shortening in NA stalk regions when compared to Y280-lineage and the human H9N2 isolates. No obvious changes NA interactions with antiviral drugs. We found that the Egyptian H9N2 viruses have seven glycosylation sites like the most recorded H9N2 viruses in the country, except A/Q/Egypt/14864V/2014 virus which has only six. The NA has four amino acid substitutions distributed in different parts of the hemadsorbing site. The most characteristic substitutions in this site were S372A and W403R these substitutions were a distinctive feature resembling to human H9N2, H2N2 and H3N2 viruses but differs from the other avian influenza viruses. These Special features of surface glycoproteins of LPAI-H9N2 viruses refer to the tendency for enhanced introductions into humans and ensuring the importance of poultry in the transfer influenza viruses.

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Molecular characterization of H9N2 avian influenza viruses isolated from vaccinated broiler chickens in northeast Iran

Cited by 20 publications

References 24 publications

Immune Escape Variants of H9N2 Influenza Viruses Containing Deletions at the Hemagglutinin Receptor Binding Site Retain Fitness In Vivo and Display Enhanced Zoonotic Characteristics

Immune Escape Variants of H9N2 Influenza Viruses Containing Deletions at the Hemagglutinin Receptor Binding Site Retain Fitness In Vivo and Display Enhanced Zoonotic Characteristics

A Global Perspective on H9N2 Avian Influenza Virus

Mutation signature in neuraminidase gene of avian influenza H9N2/G1 in Egypt

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