scholarly journals Ongoing genetic evolution of H9N2 avian influenza viruses in Iranian industrial poultry farms

2020 ◽  
Author(s):  
Mohsen Bashashati ◽  
Zohreh Mojahedi ◽  
Ali Ameghi Roudsari ◽  
Morteza Taghizadeh ◽  
Aidin Molouki ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Vaccine Strain ◽  
Broiler Chickens ◽  
Influenza Viruses ◽  
Antigenic Drift ◽  
Economic Losses ◽  
Receptor Binding Site ◽  
Evolutionary Changes ◽  
Distinct Cluster ◽  
Wide Scale

AbstractDespite the use of wide-scale vaccination programmes against the H9N2 virus, enzootic outbreaks of H9N2 avian influenza (AI) have often occurred and caused serious nationwide economic losses, particularly in broiler chickens. In this study, the haemagglutinin (HA) and neuraminidase (NA) genes of nine recent H9N2s and a common vaccine strain were fully sequenced and compared with other representative Iranian viruses. Phylogenetic analysis revealed that all Iranian viruses were grouped into the G1 sub-lineage with different clusters in which recent isolates (2014–2017) formed a distinct cluster compared to the vaccine group (1998–2004). All Iranian H9N2s exhibited low pathogenicity AI connecting peptide feature with an R/KSSR motif. Amino acid 226, located in the 220 loop of the receptor binding site, was leucine among the recent Iranian viruses, a characteristic of human influenza viruses. With an overall gradual increase in the genetic diversity of H9N2s, Bayesian skyline plots of Iranian HA and NA genes depicted a fluctuation and a relative stable situation, respectively. It is recommended to apply constant surveillance to assess any increase in viral human adaptation and evolutionary changes in circulating field H9N2s. Moreover, antigenic characterisation of the prevailing H9N2 viruses seems to be necessary for evaluating the possible antigenic drift from the vaccine strain.

scholarly journals Genetic Characteristics of Avian Influenza Virus Isolated from Wild Birds in South Korea, 2019–2020

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 381
Author(s):  
Eun-Jee Na ◽  
Young-Sik Kim ◽  
Sook-Young Lee ◽  
Yoon-Ji Kim ◽  
Jun-Soo Park ◽  
...  
Keyword(s):  
Avian Influenza ◽  
South Korea ◽  
Basic Amino Acid ◽  
Histopathological Change ◽  
Amino Acid Sequences ◽  
Wild Birds ◽  
Influenza Viruses ◽  
Economic Losses ◽  
Active Monitoring ◽  
Genetic Characteristics

Wild aquatic birds, a natural reservoir of avian influenza viruses (AIVs), transmit AIVs to poultry farms, causing huge economic losses. Therefore, the prevalence and genetic characteristics of AIVs isolated from wild birds in South Korea from October 2019 to March 2020 were investigated and analyzed. Fresh avian fecal samples (3256) were collected by active monitoring of 11 wild bird habitats. Twenty-eight AIVs were isolated. Seven HA and eight NA subtypes were identified. All AIV hosts were Anseriformes species. The HA cleavage site of 20 representative AIVs was encoded by non-multi-basic amino acid sequences. Phylogenetic analysis of the eight segment genes of the AIVs showed that most genes clustered within the Eurasian lineage. However, the HA gene of H10 viruses and NS gene of four viruses clustered within the American lineage, indicating intercontinental reassortment of AIVs. Representative viruses likely to infect mammals were selected and evaluated for pathogenicity in mice. JB21-58 (H5N3), JB42-93 (H9N2), and JB32-81 (H11N2) were isolated from the lungs, but JB31-69 (H11N9) was not isolated from the lungs until the end of the experiment at 14 dpi. None of infected mice showed clinical sign and histopathological change in the lung. In addition, viral antigens were not detected in lungs of all mice at 14 dpi. These data suggest that LPAIVs derived from wild birds are unlikely to be transmitted to mammals. However, because LPAIVs can reportedly infect mammals, including humans, continuous surveillance and monitoring of AIVs are necessary, despite their low pathogenicity.

scholarly journals Molecular Characterization of Seasonal Influenza A and B from Hospitalized Patients in Thailand in 2018–2019

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 977
Author(s):  
Kobporn Boonnak ◽  
Chayasin Mansanguan ◽  
Dennis Schuerch ◽  
Usa Boonyuen ◽  
Hatairat Lerdsamran ◽  
...  
Keyword(s):  
Amino Acid ◽  
Influenza A ◽  
Seasonal Influenza ◽  
Influenza Viruses ◽  
Surface Proteins ◽  
Antigenic Drift ◽  
Influenza B ◽  
Receptor Binding Site ◽  
Antigenic Sites ◽  
Ha Protein

Influenza viruses continue to be a major public health threat due to the possible emergence of more virulent influenza virus strains resulting from dynamic changes in virus adaptability, consequent of functional mutations and antigenic drift in surface proteins, especially hemagglutinin (HA) and neuraminidase (NA). In this study, we describe the genetic and evolutionary characteristics of H1N1, H3N2, and influenza B strains detected in severe cases of seasonal influenza in Thailand from 2018 to 2019. We genetically characterized seven A/H1N1 isolates, seven A/H3N2 isolates, and six influenza B isolates. Five of the seven A/H1N1 viruses were found to belong to clade 6B.1 and were antigenically similar to A/Switzerland/3330/2017 (H1N1), whereas two isolates belonged to clade 6B.1A1 and clustered with A/Brisbane/02/2018 (H1N1). Interestingly, we observed additional mutations at antigenic sites (S91R, S181T, T202I) as well as a unique mutation at a receptor binding site (S200P). Three-dimensional (3D) protein structure analysis of hemagglutinin protein reveals that this unique mutation may lead to the altered binding of the HA protein to a sialic acid receptor. A/H3N2 isolates were found to belong to clade 3C.2a2 and 3C.2a1b, clustering with A/Switzerland/8060/2017 (H3N2) and A/South Australia/34/2019 (H3N2), respectively. Amino acid sequence analysis revealed 10 mutations at antigenic sites including T144A/I, T151K, Q213R, S214P, T176K, D69N, Q277R, N137K, N187K, and E78K/G. All influenza B isolates in this study belong to the Victoria lineage. Five out of six isolates belong to clade 1A3-DEL, which relate closely to B/Washington/02/2009, with one isolate lacking the three amino acid deletion on the HA segment at position K162, N163, and D164. In comparison to the B/Colorado/06/2017, which is the representative of influenza B Victoria lineage vaccine strain, these substitutions include G129D, G133R, K136E, and V180R for HA protein. Importantly, the susceptibility to oseltamivir of influenza B isolates, but not A/H1N1 and A/H3N2 isolates, were reduced as assessed by the phenotypic assay. This study demonstrates the importance of monitoring genetic variation in influenza viruses regarding how acquired mutations could be associated with an improved adaptability for efficient transmission.

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

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.

scholarly journals Genetic Characterization and Pathogenicity of H7N7 and H7N9 Avian Influenza Viruses Isolated from South Korea

Viruses ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2057
Author(s):  
Eun-Jee Na ◽  
Young-Sik Kim ◽  
Yoon-Ji Kim ◽  
Jun-Soo Park ◽  
Jae-Ku Oem
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
South Korea ◽  
Influenza Viruses ◽  
The Body ◽  
Avian Influenza Viruses ◽  
Receptor Binding Site ◽  
Phylogenetic Tree Analysis ◽  
Pathogenic Avian Influenza ◽  
Ha Gene

H7 low pathogenic avian influenza viruses (LPAIVs) can mutate into highly pathogenic avian influenza viruses (HPAIVs). In addition to avian species, H7 avian influenza viruses (AIVs) also infect humans. In this study, two AIVs, H7N9 (20X-20) and H7N7 (34X-2), isolated from the feces of wild birds in South Korea in 2021, were genetically analyzed. The HA cleavage site of the two H7 Korean viruses was confirmed to be ELPKGR/GLF, indicating they are LPAIVs. There were no amino acid substitutions at the receptor-binding site of the HA gene of two H7 Korean viruses compared to that of A/Anhui/1/2013 (H7N9), which prefer human receptors. In the phylogenetic tree analysis, the HA gene of the two H7 Korean viruses shared the highest nucleotide similarity with the Korean H7 subtype AIVs. In addition, the HA gene of the two H7 Korean viruses showed high nucleotide similarity to that of the A/Jiangsu/1/2018(H7N4) virus, which is a human influenza virus originating from avian influenza virus. Most internal genes (PB2, PB1, PA, NP, NA, M, and NS) of the two H7 Korean viruses belonged to the Eurasian lineage, except for the M gene of 34X-2. This result suggests that active reassortment occurred among AIVs. In pathogenicity studies of mice, the two H7 Korean viruses replicated in the lungs of mice. In addition, the body weight of mice infected with 34X-2 decreased 7 days post-infection (dpi) and inflammation was observed in the peribronchiolar and perivascular regions of the lungs of mice. These results suggest that mammals can be infected with the two H7 Korean AIVs. Our data showed that even low pathogenic H7 AIVs may infect mammals, including humans, as confirmed by the A/Jiangsu/1/2018(H7N4) virus. Therefore, continuous monitoring and pathogenicity assessment of AIVs, even of LPAIVs, are required.

scholarly journals Pathogenicity and Transmissibility of North American H7 Low Pathogenic Avian Influenza Viruses in Chickens and Turkeys

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 163 ◽  
Author(s):  
Ishita Roy Chowdhury ◽  
Sai Yeddula ◽  
Shin-Hee Kim
Keyword(s):  
Avian Influenza ◽  
Respiratory Tract ◽  
Broiler Chickens ◽  
Influenza Viruses ◽  
Upper Respiratory Tract ◽  
Pathogenic Avian Influenza ◽  
Recent Emergence ◽  
Specific Pathogen ◽  
Upper Respiratory ◽  
Low Pathogenic Avian Influenza

Low pathogenic avian influenza (LPAI) viruses can silently circulate in poultry and wild aquatic birds and potentially mutate into highly pathogenic avian influenza (HPAI) viruses. In the U.S., recent emergence and spread of H7N8 and H7N9 HPAI viruses not only caused devastating losses to domestic poultry but also underscored the capability of LPAI viruses to mutate into HPAI viruses. Therefore, in this study, we evaluated pathogenicity and transmissibility of H7N8 and H7N9 LPAI viruses (the progenitors of HPAI viruses) in chickens and turkeys. We also included H7N2 isolated from an outbreak of LPAI in commercial chickens. H7 viruses replicated more efficiently in the respiratory tract than in the gastrointestinal tract, suggesting that their replication is restricted to the upper respiratory tract. Specifically, H7N2 replicated most efficiently in two-week-old chickens and turkeys. In contrast, H7N8 replicated least efficiently in those birds. Further, replication of H7N2 and H7N9 was restricted in the upper respiratory tract of four-week-old specific-pathogen-free (SPF) and broiler chickens. Despite their restricted replication, the two viruses efficiently transmitted from infected to naïve birds by direct contact, leading to seroconversion of contacted chickens. Our findings suggest the importance of continuous monitoring and surveillance of LPAI viruses in the fields.

scholarly journals Phenotypic Effects of Substitutions within the Receptor Binding Site of Highly Pathogenic Avian Influenza H5N1 Virus Observed during Human Infection

2020 ◽  
Vol 94 (13) ◽  
Author(s):  
Dirk Eggink ◽  
Monique Spronken ◽  
Roosmarijn van der Woude ◽  
Jocynthe Buzink ◽  
Frederik Broszeit ◽  
...  
Keyword(s):  
Amino Acid ◽  
Avian Influenza ◽  
Binding Site ◽  
Receptor Binding ◽  
Human Infection ◽  
Influenza Viruses ◽  
Receptor Specificity ◽  
Receptor Binding Site ◽  
Human Type ◽  
Human Infections

ABSTRACT Highly pathogenic avian influenza (HPAI) viruses are enzootic in wild birds and poultry and continue to cause human infections with high mortality. To date, more than 850 confirmed human cases of H5N1 virus infection have been reported, of which ∼60% were fatal. Global concern persists that these or similar avian influenza viruses will evolve into viruses that can transmit efficiently between humans, causing a severe influenza pandemic. It was shown previously that a change in receptor specificity is a hallmark for adaptation to humans and evolution toward a transmittable virus. Substantial genetic diversity was detected within the receptor binding site of hemagglutinin of HPAI A/H5N1 viruses, evolved during human infection, as detected by next-generation sequencing. Here, we investigated the functional impact of substitutions that were detected during these human infections. Upon rescue of 21 mutant viruses, most substitutions in the receptor binding site (RBS) resulted in viable virus, but virus replication, entry, and stability were often impeded. None of the tested substitutions individually resulted in a clear switch in receptor preference as measured with modified red blood cells and glycan arrays. Although several combinations of the substitutions can lead to human-type receptor specificity, accumulation of multiple amino acid substitutions within a single hemagglutinin during human infection is rare, thus reducing the risk of virus adaptation to humans. IMPORTANCE H5 viruses continue to be a threat for public health. Because these viruses are immunologically novel to humans, they could spark a pandemic when adapted to transmit between humans. Avian influenza viruses need several adaptive mutations to bind to human-type receptors, increase hemagglutinin (HA) stability, and replicate in human cells. However, knowledge on adaptive mutations during human infections is limited. A previous study showed substantial diversity within the receptor binding site of H5N1 during human infection. We therefore analyzed the observed amino acid changes phenotypically in a diverse set of assays, including virus replication, stability, and receptor specificity. None of the tested substitutions resulted in a clear step toward a human-adapted virus capable of aerosol transmission. It is notable that acquiring human-type receptor specificity needs multiple amino acid mutations, and that variability at key position 226 is not tolerated, reducing the risk of them being acquired naturally.

scholarly journals Effect of Avian Influenza H9N2 Subtype Virus Infection on Backyard Poultry Production

2021 ◽  
Vol 9 (1) ◽  
pp. 19-23
Keyword(s):  
Avian Influenza ◽  
Influenza Viruses ◽  
Economic Losses ◽  
Poultry Production ◽  
Poultry Industry ◽  
Backyard Poultry ◽  
H9n2 Subtype ◽  
Pathogenic Avian Influenza ◽  
The World ◽  
Avian Influenza H9n2

Avian influenza is a viral pandemic disease of humans and birds, including commercial and house poultry. Avian influenza is a major concern around the world, which causes serious economic losses in the poultry industry, mainly in home backyard poultry. The backyard poultry is the potential source of income for rural people and indirectly contributes to decreasing the poverty of household women. Besides, in many developing countries, villagers full fill a part of their food demand by the backyard poultry; however, this sector is directly affected by biosecurity risks, including high and low pathogenic avian influenza infections like avian influenza H9N2 subtype. Avian influenza H9N2 subtype has low pathogenic zoonotic importance but still causes serious threats to the poultry industry. The backyard poultry industry is directly affected by this infection due to direct contact with wild migratory birds locating in different regions of the world. Antigenic drift and shift are one of the major conflicts of this infection resulting from a few days to a few months up to many years and also the main reason for the uncontrollable mutation in this infection. All over the world, there is no serious action taken to prevent the H9N2 subtype infection in backyard poultry. This situation has become severe because of the widespread of highly pathogenic avian influenza viruses in the past few years.

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