scholarly journals Avian Influenza & Human Health

2014 ◽  
Vol 5 (1) ◽  
pp. 35-38
Author(s):  
Prosun Roy ◽  
SM Rashed-ul Islam ◽  
Farhana Rahman ◽  
Md Mahmudur Rahman Siddiqui
Keyword(s):  
Avian Influenza ◽  
Human Health ◽  
Viral Infections ◽  
Influenza Pandemic ◽  
Animal Health ◽  
Genetic Mutation ◽  
Influenza Viruses ◽  
Avian Influenza Viruses ◽  
Influenza Pandemics ◽  
The World

The world is now under human pandemic threat by avian influenza viruses. As the human, animal and the environment interact closely from the dawn of the civilization, human health is tremendously influenced by animal health and their health issues. In last few centuries the world has suffered a number of influenza pandemics killing millions of people such as Spanish Flu (1918), Asiatic or Russian Flu (1889-1890), Asian Flu (1957-1958) etc. The exceptional capability of genetic mutation of the influenza viruses offered threats to the whole world time to time. Like all other countries Bangladesh also not away from the heat of the situation. Human cases of avian influenza subtype H1N1, H3, H5N1, and H9N2 have already been reported from Bangladesh. This article reviews the information available on pandemic potential of avian influenza viruses. The article also sheds light on different avian influenza viruses along with some emphasis on clinical and preventive aspects of the avian influenza viral infections, and on avian influenza pandemic preparedness of Bangladesh. DOI: http://dx.doi.org/10.3329/akmmcj.v5i1.18839 Anwer Khan Modern Medical College Journal Vol. 5, No. 1: January 2014, Pages 35-38

scholarly journals Lessons From Influenza Pandemics of the Last 100 Years

2019 ◽  
Author(s):  
Arnold S Monto ◽  
Keiji Fukuda
Keyword(s):  
Avian Influenza ◽  
Seasonal Influenza ◽  
Influenza Pandemic ◽  
Risk Groups ◽  
Influenza Viruses ◽  
Avian Influenza Viruses ◽  
Influenza Pandemics ◽  
Fundamental Difficulty ◽  
1918 Influenza ◽  
The Impact

Abstract Seasonal influenza is an annual occurrence, but it is the threat of pandemics that produces universal concern. Recurring reports of avian influenza viruses severely affecting humans have served as constant reminders of the potential for another pandemic. Review of features of the 1918 influenza pandemic and subsequent ones helps in identifying areas where attention in planning is critical. Key among such issues are likely risk groups and which interventions to employ. Past pandemics have repeatedly underscored, for example, the vulnerability of groups such as pregnant women and taught other lessons valuable for future preparedness. While a fundamental difficulty in planning for the next pandemic remains their unpredictability and infrequency, this uncertainty can be mitigated, in part, by optimizing the handling of the much more predictable occurrence of seasonal influenza. Improvements in antivirals and novel vaccine formulations are critical in lessening the impact of both pandemic and seasonal influenza.

scholarly journals Continuous Reassortment of Clade 2.3.4.4 H5N6 Highly Pathogenetic Avian Influenza Viruses Demonstrating High Risk to Public Health

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 670 ◽  
Author(s):  
Huanan Li ◽  
Qian Li ◽  
Bo Li ◽  
Yang Guo ◽  
Jinchao Xing ◽  
...  
Keyword(s):  
Public Health ◽  
High Risk ◽  
Avian Influenza ◽  
Migratory Birds ◽  
Influenza Pandemic ◽  
Influenza Viruses ◽  
Avian Influenza Viruses ◽  
The World

Since it firstly emerged in China in 2013, clade 2.3.4.4 H5N6 highly pathogenic avian influenza viruses (HPAIVs) has rapidly replaced predominant H5N1 to become the dominant H5 subtype in China, especially in ducks. Not only endemic in China, it also crossed the geographical barrier and emerged in South Korea, Japan, and Europe. Here, we analyzed the genetic properties of the clade 2.3.4.4 H5N6 HPAIVs with full genome sequences available online together with our own isolates. Phylogenetic analysis showed that clade 2.3.4.4 H5N6 HPAIVs continuously reassorted with local H5, H6, and H7N9/H9N2. Species analysis reveals that aquatic poultry and migratory birds became the dominant hosts of H5N6. Adaption to aquatic poultry might help clade 2.3.4.4 H5N6 better adapt to migratory birds, thus enabling it to become endemic in China. Besides, migratory birds might help clade 2.3.4.4 H5N6 transmit all over the world. Clade 2.3.4.4 H5N6 HPAIVs also showed a preference for α2,6-SA receptors when compared to other avian origin influenza viruses. Experiments in vitro and in vivo revealed that clade 2.3.4.4 H5N6 HPAIVs exhibited high replication efficiency in both avian and mammal cells, and it also showed high pathogenicity in both mice and chickens, demonstrating high risk to public health. Considering all the factors together, adaption to aquatic poultry and migratory birds helps clade 2.3.4.4 H5N6 overcome the geographical isolation, and it has potential to be the next influenza pandemic in the world, making it worthy of our attention.

scholarly journals Novel reassortant of H9N2 avian influenza viruses isolated from chickens and quails in Egypt

2021 ◽  
pp. 2142-2149
Author(s):  
Moataz Elsayed ◽  
AbdelSatar Arafa ◽  
Shahira Abdelwahab ◽  
Amro Hashish ◽  
Ahmed Youssef
Keyword(s):  
Avian Influenza ◽  
Influenza Pandemic ◽  
Phylogenetic Analyses ◽  
Influenza Viruses ◽  
H9n2 Virus ◽  
Avian Influenza Viruses ◽  
Genetic Changes ◽  
Genome Variability ◽  
Commercial Chicken ◽  
Amino Acid Mutations

Background and Aim: Poultry infections with H9N2 avian influenza viruses (AIVs) are endemic in Egypt. This study determined the genetic changes in the sequences of H9N2 AIVs isolated from chicken and quails in Egypt, including determining genetic reassortment and detecting the main genetic changes in hemagglutinin (HA) and neuraminidase (NA) genes. Materials and Methods: Swab samples were collected from chicken and quails, examined through reverse transcription-polymerase chain reaction, and AIVs from positive samples were isolated in embryonated chicken eggs. Complete genome sequencing and phylogenetic analyses were conducted for two H9N2 AIV isolates, and sequences of HA and NA gene segments were analyzed in another two isolates. Results: A novel reassortant virus was identified from a commercial chicken flock (A/chicken/Egypt/374V/2016) and quails from a live bird market (A/quail/Egypt/1253V/2016). The reassortant viruses acquired four genome segments from the classic Egyptian H9N2 viruses (HA, NA, NP, and M) and four segments from Eurasian AIVs (PB2, PB1, PA, and NS). Many genetic changes have been demonstrated in HA and NA genes. The isolated novel reassortant H9N2 virus from quails showed amino acid mutations in the antigenic sites on the globular head of the mature HA monomer matched with the parent Egyptian H9N2 virus. Conclusion: This work described the genetic characterization of a novel reassortment of the H9N2 virus in Egypt. The emergence of new reassorted AIV viruses and genome variability raises the concern of an influenza pandemic with zoonotic potentials.

scholarly journals Pandemic Threat Posed by Avian Influenza A Viruses

2001 ◽  
Vol 14 (1) ◽  
pp. 129-149 ◽  
Author(s):  
Taisuke Horimoto ◽  
Yoshihiro Kawaoka
Keyword(s):  
Hong Kong ◽  
Avian Influenza ◽  
Influenza A ◽  
Mammalian Species ◽  
Influenza Viruses ◽  
Human Populations ◽  
Avian Influenza Viruses ◽  
Influenza Pandemics ◽  
Avian Virus ◽  
H5n1 Influenza

SUMMARY Influenza pandemics, defined as global outbreaks of the disease due to viruses with new antigenic subtypes, have exacted high death tolls from human populations. The last two pandemics were caused by hybrid viruses, or reassortants, that harbored a combination of avian and human viral genes. Avian influenza viruses are therefore key contributors to the emergence of human influenza pandemics. In 1997, an H5N1 influenza virus was directly transmitted from birds in live poultry markets in Hong Kong to humans. Eighteen people were infected in this outbreak, six of whom died. This avian virus exhibited high virulence in both avian and mammalian species, causing systemic infection in both chickens and mice. Subsequently, another avian virus with the H9N2 subtype was directly transmitted from birds to humans in Hong Kong. Interestingly, the genes encoding the internal proteins of the H9N2 virus are genetically highly related to those of the H5N1 virus, suggesting a unique property of these gene products. The identification of avian viruses in humans underscores the potential of these and similar strains to produce devastating influenza outbreaks in major population centers. Although highly pathogenic avian influenza viruses had been identified before the 1997 outbreak in Hong Kong, their devastating effects had been confined to poultry. With the Hong Kong outbreak, it became clear that the virulence potential of these viruses extended to humans.

scholarly journals Zoonotic Potential of Currently Circulating Avian Influenza Viruses

2020 ◽  
Vol 39 (1) ◽  
pp. 8-14
Author(s):  
Vladimir Savić
Keyword(s):  
Avian Influenza ◽  
Influenza A ◽  
Human Infection ◽  
Influenza Viruses ◽  
Influenza A Viruses ◽  
Avian Influenza Viruses ◽  
Influenza Pandemics ◽  
Human Infections ◽  
Virus Adaptation ◽  
Efficient Transmission

Over the past and the current centuries, human influenza pandemics have been attributable to viruses with an avian ancestry. Birds are the main source of influenza A viruses and harbour a variety of antigenic subtypes. Certain avian influenza viruses are capable for cross-species transmission including human infections. Although sustained intrehuman transmission of such viruses has not been documented so far, each human infection with avian influenza viruses provides chances for the virus adaptation towards efficient transmission within human population. Here are reviewed currently circulating avian influenza viruses that are of major significance for public health.

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

2017 ◽  
Vol 91 (14) ◽  
Author(s):  
Thomas P. Peacock ◽  
Donald J. Benton ◽  
Joe James ◽  
Jean-Remy Sadeyen ◽  
Pengxiang Chang ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Receptor Binding ◽  
Immune Escape ◽  
Influenza Pandemic ◽  
Influenza Viruses ◽  
Viral Fitness ◽  
Antigenic Drift ◽  
Zoonotic Infection ◽  
Avian Influenza Viruses ◽  
The Impact

ABSTRACT 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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