Multiple amino acid substitutions involved in the virulence enhancement of an H3N2 avian influenza A virus isolated from wild waterfowl in mice

Highly pathogenic avian influenza A virus subtype H5N1 can potentially generate novel variants during replication of infected hosts. To determine which H5N1 variants predominate in wild birds, we determined the sequences of RT-PCR amplified viral genes from several organs of infected chickens and ducks from Egypt, where H5N1 outbreaks in birds are endemic. Comparison of the sequences in viruses from trachea, lung, brain and liver revealed diversification with different amino acid substitutions in different ducks, but no diversification in chickens. These specific amino acid substitutions were rare among viruses currently circulating in Egypt. In addition, the H5N1 variants showed distinct growth kinetics in duck, canine and human cells. Our findings suggested that ducks can generate H5N1 variants with novel amino acid substitutions that might serve as aetiological agents for new influenza virus outbreaks and epidemics.

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Risk of resistant avian influenza A virus in wild waterfowl as a result of environmental release of oseltamivir

Infection Ecology & Epidemiology ◽

10.3402/iee.v6.32870 ◽

2016 ◽

Vol 6 (1) ◽

pp. 32870 ◽

Cited By ~ 3

Author(s):

Anna Gillman

Keyword(s):

Avian Influenza ◽

Influenza A Virus ◽

Influenza A ◽

Avian Influenza A Virus ◽

Wild Waterfowl

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Newcastle Disease and Avian Influenza A Virus in Wild Waterfowl in South Africa

Avian Diseases ◽

10.2307/1593107 ◽

2000 ◽

Vol 44 (3) ◽

pp. 655 ◽

Cited By ~ 33

Author(s):

S. Pfitzer ◽

D. J. Verwoerd ◽

G. H. Gerdes ◽

A. E. Labuschagne ◽

A. Erasmus ◽

...

Keyword(s):

South Africa ◽

Avian Influenza ◽

Influenza A Virus ◽

Newcastle Disease ◽

Influenza A ◽

Avian Influenza A Virus ◽

Wild Waterfowl

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Multiple Natural Substitutions in Avian Influenza A Virus PB2 Facilitate Efficient Replication in Human Cells

Journal of Virology ◽

10.1128/jvi.00130-16 ◽

2016 ◽

Vol 90 (13) ◽

pp. 5928-5938 ◽

Cited By ~ 24

Author(s):

Benjamin Mänz ◽

Miranda de Graaf ◽

Ramona Mögling ◽

Mathilde Richard ◽

Theo M. Bestebroer ◽

...

Keyword(s):

Influenza Virus ◽

Amino Acid ◽

Avian Influenza ◽

Mammalian Cells ◽

Influenza A ◽

Polymerase Activity ◽

Host Adaptation ◽

Influenza Viruses ◽

Amino Acid Substitutions ◽

Avian Influenza A Virus

ABSTRACTA strong restriction of the avian influenza A virus polymerase in mammalian cells generally limits viral host-range switching. Although substitutions like E627K in the PB2 polymerase subunit can facilitate polymerase activity to allow replication in mammals, many human H5N1 and H7N9 viruses lack this adaptive substitution. Here, several previously unknown, naturally occurring, adaptive substitutions in PB2 were identified by bioinformatics, and their enhancing activity was verified usingin vitroassays. Adaptive substitutions enhanced polymerase activity and virus replication in mammalian cells for avian H5N1 and H7N9 viruses but not for a partially human-adapted H5N1 virus. Adaptive substitutions toward basic amino acids were frequent and were mostly clustered in a putative RNA exit channel in a polymerase crystal structure. Phylogenetic analysis demonstrated divergent dependency of influenza viruses on adaptive substitutions. The novel adaptive substitutions found in this study increase basic understanding of influenza virus host adaptation and will help in surveillance efforts.IMPORTANCEInfluenza viruses from birds jump the species barrier into humans relatively frequently. Such influenza virus zoonoses may pose public health risks if the virus adapts to humans and becomes a pandemic threat. Relatively few amino acid substitutions—most notably in the receptor binding site of hemagglutinin and at positions 591 and 627 in the polymerase protein PB2—have been identified in pandemic influenza virus strains as determinants of host adaptation, to facilitate efficient virus replication and transmission in humans. Here, we show that substantial numbers of amino acid substitutions are functionally compensating for the lack of the above-mentioned mutations in PB2 and could facilitate influenza virus emergence in humans.

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Development of Neuraminidase Subtype-Specific Reference Antisera by Recombinant Protein Expressed in Baculovirus

Clinical and Vaccine Immunology ◽

10.1128/cvi.00385-12 ◽

2012 ◽

Vol 20 (2) ◽

pp. 140-145 ◽

Cited By ~ 3

Author(s):

Kyu-Jun Lee ◽

Jun-Gu Choi ◽

Hyun-Mi Kang ◽

Kwang-Il Kim ◽

Choi-Kyu Park ◽

...

Keyword(s):

Influenza Virus ◽

Avian Influenza ◽

Influenza A Virus ◽

Diagnostic Tests ◽

Influenza A ◽

Recombinant Baculovirus ◽

Cross Reactivity ◽

Specific Reference ◽

Simple Method ◽

Avian Influenza A Virus

ABSTRACTOutbreaks of avian influenza A virus infection, particularly the H5N1 strains that have affected birds and some humans for the past 15 years, have highlighted the need for increased surveillance and disease control. Such measures require diagnostic tests to detect and characterize the different subtypes of influenza virus. In the current study, a simple method for producing reference avian influenza virus antisera to be used in diagnostic tests was developed. Antisera of nine avian influenza A virus neuraminidases (NA) used for NA subtyping were produced using a recombinant baculovirus. The recombinant NA (rNA) proteins were expressed in Sf9 insect cells and inoculated intramuscularly into specific-pathogen-free chickens with the ISA70 adjuvant. The NA inhibition antibody titers of the rNA antiserum were in the ranges of 5 to 8 and 6 to 9 log2units after the primary and boost immunizations, respectively. The antisera were subtype specific, showing low cross-reactivity against every other NA subtype using the conventional thiobarbituric acid NA inhibition assay. These results suggest that this simple method for producing reference NA antisera without purification may be useful for the diagnosis and surveillance of influenza virus.

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Characterization of a Human H5N1 Influenza A Virus Isolated in 2003

Journal of Virology ◽

10.1128/jvi.79.15.9926-9932.2005 ◽

2005 ◽

Vol 79 (15) ◽

pp. 9926-9932 ◽

Cited By ~ 70

Author(s):

Kyoko Shinya ◽

Masato Hatta ◽

Shinya Yamada ◽

Ayato Takada ◽

Shinji Watanabe ◽

...

Keyword(s):

Hong Kong ◽

Avian Influenza ◽

Influenza A Virus ◽

Influenza A ◽

Mainland China ◽

Virus Infections ◽

Influenza A Viruses ◽

H5n1 Avian Influenza Virus ◽

H5n1 Influenza ◽

Avian Influenza A Virus

ABSTRACT In 2003, H5N1 avian influenza virus infections were diagnosed in two Hong Kong residents who had visited the Fujian province in mainland China, affording us the opportunity to characterize one of the viral isolates, A/Hong Kong/213/03 (HK213; H5N1). In contrast to H5N1 viruses isolated from humans during the 1997 outbreak in Hong Kong, HK213 retained several features of aquatic bird viruses, including the lack of a deletion in the neuraminidase stalk and the absence of additional oligosaccharide chains at the globular head of the hemagglutinin molecule. It demonstrated weak pathogenicity in mice and ferrets but caused lethal infection in chickens. The original isolate failed to produce disease in ducks but became more pathogenic after five passages. Taken together, these findings portray the HK213 isolate as an aquatic avian influenza A virus without the molecular changes associated with the replication of H5N1 avian viruses in land-based poultry such as chickens. This case challenges the view that adaptation to land-based poultry is a prerequisite for the replication of aquatic avian influenza A viruses in humans.

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Characterization of H9N2 influenza A viruses isolated from chicken products imported into Japan from China

Epidemiology and Infection ◽

10.1017/s0950268806006728 ◽

2006 ◽

Vol 135 (3) ◽

pp. 386-391 ◽

Cited By ~ 13

Author(s):

M. MASE ◽

M. ETO ◽

K. IMAI ◽

K. TSUKAMOTO ◽

S. YAMAGUCHI

Keyword(s):

Influenza Virus ◽

Amino Acid ◽

Avian Influenza ◽

Avian Influenza Virus ◽

Influenza A ◽

H9n2 Virus ◽

Amino Acid Substitutions ◽

Influenza A Viruses ◽

Potential Sources

We characterized eleven H9N2 influenza A viruses isolated from chicken products imported from China. Genetically they were classified into six distinct genotypes, including five already known genotypes and one novel genotype. This suggested that such multiple genotypes of the H9N2 virus have possibly already become widespread and endemic in China. Two isolates have amino-acid substitutions that confer resistance to amantadine in the M2 region, and this supported the evidence that this mutation might be a result of the wide application of amantadine for avian influenza treatment in China. These findings emphasize the importance of surveillance for avian influenza virus in this region, and of quarantining imported chicken products as potential sources for the introduction of influenza virus.

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Evolution and Adaptation of the Avian H7N9 Virus into the Human Host

Microorganisms ◽

10.3390/microorganisms8050778 ◽

2020 ◽

Vol 8 (5) ◽

pp. 778

Author(s):

Andrew T. Bisset ◽

Gerard F. Hoyne

Keyword(s):

Amino Acid ◽

Avian Influenza ◽

Influenza A ◽

Amino Acid Sequences ◽

Influenza Viruses ◽

Amino Acid Substitutions ◽

Upper Respiratory Tract ◽

Viral Polymerase ◽

Evolutionary Changes ◽

Avian Origin

Influenza viruses arise from animal reservoirs, and have the potential to cause pandemics. In 2013, low pathogenic novel avian influenza A(H7N9) viruses emerged in China, resulting from the reassortment of avian-origin viruses. Following evolutionary changes, highly pathogenic strains of avian influenza A(H7N9) viruses emerged in late 2016. Changes in pathogenicity and virulence of H7N9 viruses have been linked to potential mutations in the viral glycoproteins hemagglutinin (HA) and neuraminidase (NA), as well as the viral polymerase basic protein 2 (PB2). Recognizing that effective viral transmission of the influenza A virus (IAV) between humans requires efficient attachment to the upper respiratory tract and replication through the viral polymerase complex, experimental evidence demonstrates the potential H7N9 has for increased binding affinity and replication, following specific amino acid substitutions in HA and PB2. Additionally, the deletion of extended amino acid sequences in the NA stalk length was shown to produce a significant increase in pathogenicity in mice. Research shows that significant changes in transmissibility, pathogenicity and virulence are possible after one or a few amino acid substitutions. This review aims to summarise key findings from that research. To date, all strains of H7N9 viruses remain restricted to avian reservoirs, with no evidence of sustained human-to-human transmission, although mutations in specific viral proteins reveal the efficacy with which these viruses could evolve into a highly virulent and infectious, human-to-human transmitted virus.

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