scholarly journals Genetic, Molecular, and Pathogenic Characterization of the H9N2 Avian Influenza Viruses Currently Circulating in South China

Viruses ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1040 ◽  
Author(s):  
Hailiang Sun ◽  
Jiate Lin ◽  
Zhiting Liu ◽  
Yanan Yu ◽  
Meihua Wu ◽  
...  
Keyword(s):  
Avian Influenza ◽  
South China ◽  
Mammalian Cells ◽  
Phylogenetic Analyses ◽  
Human Infection ◽  
Influenza Viruses ◽  
Upper Respiratory Tract ◽  
Species Barrier ◽  
Viral Shedding

The prevalence and variation of the H9N2 avian influenza virus (AIV) pose a threat to public health. A total of eight viruses isolated from farmed poultry in South China during 2017–2018 were selected as representative strains for further systematic study. Phylogenetic analyses indicated that these prevalent viruses belong to the Y280-like lineage and that the internal genes are highly similar to those of recently circulating human H7N9 viruses. The receptor-binding assay showed that most of the H9N2 isolates preferentially bound to the human-like receptor, increasing the risk of them crossing the species barrier and causing human infection. Our in vitro, multi-step growth curve results indicate these viruses can effectively replicate in mammalian cells. Infection in mice showed that three viruses effectively replicated in the lung of mice. Infection in swine revealed that the viruses readily replicated in the upper respiratory tract of pig and effectively induced viral shedding. Our findings suggested that the H9N2 AIVs circulating in poultry recently acquired an enhanced ability to transmit from avian to mammalians, including humans. Based on our findings, we propose that it is essential to strengthen the efforts to surveil and test the pathogenicity of H9N2 AIVs.

scholarly journals Vaccination with Consensus H7 Elicits Broadly Reactive and Protective Antibodies against Eurasian and North American Lineage H7 Viruses

Vaccines ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 143
Author(s):  
Gendeal M. Fadlallah ◽  
Fuying Ma ◽  
Zherui Zhang ◽  
Mengchan Hao ◽  
Juefu Hu ◽  
...  
Keyword(s):  
Avian Influenza ◽  
North American ◽  
Human Infection ◽  
Influenza Viruses ◽  
Avian Influenza Viruses ◽  
Lethal Challenge ◽  
Protective Antibodies ◽  
H7 Subtype ◽  
H7n3 Virus

H7 subtype avian influenza viruses have caused outbreaks in poultry, and even human infection, for decades in both Eurasia and North America. Although effective vaccines offer the best protection against avian influenza viruses, antigenically distinct Eurasian and North American lineage subtype H7 viruses require the development of cross-protective vaccine candidates. In this study, a methodology called computationally optimized broadly reactive antigen (COBRA) was used to develop four consensus H7 antigens (CH7-22, CH7-24, CH7-26, and CH7-28). In vitro experiments confirmed the binding of monoclonal antibodies to the head and stem domains of cell surface-expressed consensus HAs, indicating display of their antigenicity. Immunization with DNA vaccines encoding the four antigens was evaluated in a mouse model. Broadly reactive antibodies against H7 viruses from Eurasian and North American lineages were elicited and detected by binding, inhibition, and neutralizing analyses. Further infection with Eurasian H7N9 and North American H7N3 virus strains confirmed that CH7-22 and CH7-24 conferred the most effective protection against hetero-lethal challenge. Our data showed that the consensus H7 vaccines elicit a broadly reactive, protective response against Eurasian and North American lineage H7 viruses, which are suitable for development against other zoonotic influenza viruses.

scholarly journals PB2 Protein of a Highly Pathogenic Avian Influenza Virus Strain A/chicken/Yamaguchi/7/2004 (H5N1) Determines Its Replication Potential in Pigs

2008 ◽  
Vol 83 (4) ◽  
pp. 1572-1578 ◽  
Author(s):  
Rashid Manzoor ◽  
Yoshihiro Sakoda ◽  
Naoki Nomura ◽  
Yoshimi Tsuda ◽  
Hiroichi Ozaki ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Mammalian Cells ◽  
Reverse Genetics ◽  
Single Gene ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
Upper Respiratory Tract ◽  
Reassortant Virus ◽  
Range Restriction

ABSTRACT It has been shown that not all but most of the avian influenza viruses replicate in the upper respiratory tract of pigs (H. Kida et al., J. Gen. Virol. 75:2183-2188, 1994). It was shown that A/chicken/Yamaguchi/7/2004 (H5N1) [Ck/Yamaguchi/04 (H5N1)] did not replicate in pigs (N. Isoda et al., Arch. Virol. 151:1267-1279, 2006). In the present study, the genetic basis for this host range restriction was determined using reassortant viruses generated between Ck/Yamaguchi/04 (H5N1) and A/swine/Hokkaido/2/1981 (H1N1) [Sw/Hokkaido/81 (H1N1)]. Two in vivo-generated single-gene reassortant virus clones of the H5N1 subtype (virus clones 1 and 2), whose PB2 gene was of Sw/Hokkaido/81 (H1N1) origin and whose remaining seven genes were of Ck/Yamaguchi/04 (H5N1) origin, were recovered from the experimentally infected pigs. The replicative potential of virus clones 1 and 2 was further confirmed by using reassortant virus (rg-Ck-Sw/PB2) generated by reverse genetics. Interestingly, the PB2 gene of Ck/Yamaguchi/04 (H5N1) did not restrict the replication of Sw/Hokkaido/81 (H1N1), as determined by using reassortant virus rg-Sw-Ck/PB2. The rg-Sw-Ck/PB2 virus replicated to moderate levels and for a shorter duration than parental Sw/Hokkaido/81 (H1N1). Sequencing of two isolates recovered from the pigs inoculated with rg-Sw-Ck/PB2 revealed either the D256G or the E627K amino acid substitution in the PB2 proteins of the isolates. The D256G and E627K mutations enhanced viral polymerase activity in the mammalian cells, correlating with replication of virus in pigs. These results indicate that the PB2 protein restricts the growth of Ck/Yamaguchi/04 (H5N1) in pigs.

scholarly journals The PB2 Polymerase Host Adaptation Substitutions Prime Avian Indonesia Sub Clade 2.1 H5N1 Viruses for Infecting Humans

Viruses ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 292 ◽  
Author(s):  
Pui Wang ◽  
Wenjun Song ◽  
Bobo Mok ◽  
Min Zheng ◽  
Siu-Ying Lau ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
H5n1 Virus ◽  
Human Infection ◽  
Influenza Viruses ◽  
Avian Species ◽  
Adaptive Mutation ◽  
Efficient Replication ◽  
Human Infections

Significantly higher numbers of human infections with H5N1 virus have occurred in Indonesia and Egypt, compared with other affected areas, and it is speculated that there are specific viral factors for human infection with avian H5N1 viruses in these locations. We previously showed PB2-K526R is present in 80% of Indonesian H5N1 human isolates, which lack the more common PB2-E627K substitution. Testing the hypothesis that this mutation may prime avian H5N1 virus for human infection, we showed that: (1) K526R is rarely found in avian influenza viruses but was identified in H5N1 viruses 2–3 years after the virus emerged in Indonesia, coincident with the emergence of H5N1 human infections in Indonesia; (2) K526R is required for efficient replication of Indonesia H5N1 virus in mammalian cells in vitro and in vivo and reverse substitution to 526K in human isolates abolishes this ability; (3) Indonesian H5N1 virus, which contains K526R-PB2, is stable and does not further acquire E627K following replication in infected mice; and (4) virus containing K526R-PB2 shows no fitness deficit in avian species. These findings illustrate an important mechanism in which a host adaptive mutation that predisposes avian H5N1 virus towards infecting humans has arisen with the virus becoming prevalent in avian species prior to human infections occurring. A similar mechanism is observed in the Qinghai-lineage H5N1 viruses that have caused many human cases in Egypt; here, E627K predisposes towards human infections. Surveillance should focus on the detection of adaptation markers in avian strains that prime for human infection.

scholarly journals Ostrich Involvement in the Selection of H5N1 Influenza Virus Possessing Mammalian-Type Amino Acids in the PB2 Protein

2009 ◽  
Vol 83 (24) ◽  
pp. 13015-13018 ◽  
Author(s):  
Kyoko Shinya ◽  
Akiko Makino ◽  
Makoto Ozawa ◽  
Jin Hyun Kim ◽  
Yuko Sakai-Tagawa ◽  
...  
Keyword(s):  
Amino Acids ◽  
Avian Influenza ◽  
Mammalian Cells ◽  
Influenza A ◽  
Influenza Viruses ◽  
High Rate ◽  
Qinghai Lake ◽  
H5n1 Influenza

ABSTRACT Amino acids at positions 627 and 701 in the PB2 protein (PB2-627 and PB2-701, respectively) of avian influenza A viruses affect virus replication in some mammalian cells. Highly pathogenic H5N1 influenza viruses possessing mammalian-type PB2-627 were detected during the Qinghai Lake outbreak in 2005 and spread to Europe and Africa. Via a database search, we found a high rate of viral isolates from Ratitae, including ostrich, possessing mammalian-type PB2-627 or -701. Here, we report that H5N1 avian influenza viruses possessing mammalian-type amino acids in PB2-627 or -701 are selected during replication in ostrich cells in vitro and in vivo.

scholarly journals H5N2 Avian Influenza Outbreak in Texas in 2004: the First Highly Pathogenic Strain in the United States in 20 Years?

2005 ◽  
Vol 79 (17) ◽  
pp. 11412-11421 ◽  
Author(s):  
Chang-Won Lee ◽  
David E. Swayne ◽  
Jose A. Linares ◽  
Dennis A. Senne ◽  
David L. Suarez
Keyword(s):  
United States ◽  
Amino Acid ◽  
Avian Influenza ◽  
Cleavage Site ◽  
Basic Amino Acid ◽  
The United States ◽  
Influenza Viruses ◽  
Single Point Mutation ◽  
Highly Pathogenic

ABSTRACT In early 2004, an H5N2 avian influenza virus (AIV) that met the molecular criteria for classification as a highly pathogenic AIV was isolated from chickens in the state of Texas in the United States. However, clinical manifestations in the affected flock were consistent with avian influenza caused by a low-pathogenicity AIV and the representative virus (A/chicken/Texas/298313/04 [TX/04]) was not virulent for experimentally inoculated chickens. The hemagglutinin (HA) gene of the TX/04 isolate was similar in sequence to A/chicken/Texas/167280-4/02 (TX/02), a low-pathogenicity AIV isolate recovered from chickens in Texas in 2002. However, the TX/04 isolate had one additional basic amino acid at the HA cleavage site, which could be attributed to a single point mutation. The TX/04 isolate was similar in sequence to TX/02 isolate in several internal genes (NP, M, and NS), but some genes (PA, PB1, and PB2) had sequence of a clearly different origin. The TX/04 isolate also had a stalk deletion in the NA gene, characteristic of a chicken-adapted AIV. By analyzing viruses constructed by in vitro mutagenesis followed by reverse genetics, we found that the pathogenicity of the TX/04 virus could be increased in vitro and in vivo by the insertion of an additional basic amino acid at the HA cleavage site and not by the loss of a glycosylation site near the cleavage site. Our study provides the genetic and biologic characteristics of the TX/04 isolate, which highlight the complexity of the polygenic nature of the virulence of influenza viruses.

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.

The Single E627K Amino Acid Substitution in PB2 Enhances the Pathogenicity of Wild-Bird-Origin H6N6 Subtype Avian Influenza Virus in Mice

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Miura H ◽  
◽  
Ozeki Y ◽  
Omatsu T ◽  
Katayama Y ◽  
...  
Keyword(s):  
Amino Acid ◽  
Avian Influenza ◽  
Wild Bird ◽  
Virus Transmission ◽  
Influenza Viruses ◽  
Whole Genome Sequence ◽  
Species Barrier ◽  
The Impact ◽  
Original Virus ◽  
Wild Waterfowl

Avian Influenza Viruses (AIVs) are harbored by wild waterfowl as a natural host, and there is a species barrier restricting virus transmission from birds to mammals, including humans. However, it has been reported that, through genetic mutations, AIVs occasionally infect mammals and acquire high pathogenicity. The Amino Acid (aa) substitution of glutamic acid to lysine at position 627 (E627K) in polymerase basic protein 2 (PB2) is one of the wellknown factors underlying mammalian adaptation. Although this substitution was previously observed in mammalian-adapted H5, H7, and H9 AIV subtypes, the impact of this mutation on the mammalian adaptation of other AIV subtypes is not fully verified. Here, we isolated the low pathogenic AIV subtype H6N6 from a wild bird fecal sample in Tokachi Subprefecture, Hokkaido, Japan. We passaged this H6N6 subtype in BALB/c mice four times and acquired the mouse-adapted virus. Whole-genome sequence analysis showed that the adapted virus had only one aa substitution (E627K) in PB2. The adapted virus-inoculated mice tended to show increased weight loss and mortality compared with the original virus-inoculated mice. The viral titer in the lungs of the adapted virus-inoculated mice was significantly higher than that of the original virus-inoculated mice. Additionally, the virus isolated from the lung of the original virus-inoculated mice with serious symptoms harbored the E627K substitution. Our findings indicate the possibility that the PB2 E627K substitution in H6N6 subtype AIV rapidly appears in mammalian hosts and contributes to the enhanced pathogenicity of this virus.

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 Insights into the Acquisition of Virulence of Avian Influenza Viruses during a Single Passage in Ferrets

Viruses ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 915
Author(s):  
Butler ◽  
Middleton ◽  
Haining ◽  
Layton ◽  
Rockman ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Respiratory Tract ◽  
Severe Disease ◽  
Influenza Viruses ◽  
Mammalian Host ◽  
Upper Respiratory Tract ◽  
Avian Influenza Viruses ◽  
Single Passage ◽  
H5n1 Isolate ◽  
High Pathogenicity

Circulating avian influenza viruses pose a significant threat, with human infections occurring infrequently but with potentially severe consequences. To examine the dynamics and locale of the adaptation process of avian influenza viruses when introduced to a mammalian host, we infected ferrets with H5N1 viruses. As expected, all ferrets infected with the human H5N1 isolate A/Vietnam/1203/2004 showed severe disease and virus replication outside the respiratory tract in multiple organs including the brain. In contrast infection of ferrets with the avian H5N1 virus A/Chicken/Laos/Xaythiani26/2006 showed a different collective pattern of infection; many ferrets developed and cleared a mild respiratory infection but a subset (25–50%), showed extended replication in the upper respiratory tract and developed infection in distal sites. Virus from these severely infected ferrets was commonly found in tissues that included liver and small intestine. In most instances the virus had acquired the common virulence substitution PB2 E627K but, in one case, a previously unidentified combination of two amino acid substitutions at PB2 S489P and NP V408I, which enhanced polymerase activity, was found. We noted that virus with high pathogenicity adaptations could be dominant in an extra-respiratory site without being equally represented in the nasal wash. Further ferret passage of these mutated viruses resulted in high pathogenicity in all ferrets. These findings illustrate the remarkable ability of avian influenza viruses that avoid clearance in the respiratory tract, to mutate towards a high pathogenicity phenotype during just a single passage in ferrets and also indicate a window of less than 5 days in which treatment may curtail systemic infection.

scholarly journals Development of a duplex TaqMan real-time RT-PCR assay for simultaneous detection of newly emerged H5N6 influenza viruses

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Lin Liu ◽  
Ying Zhang ◽  
Pengfei Cui ◽  
Congcong Wang ◽  
Xianying Zeng ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Simultaneous Detection ◽  
Reaction System ◽  
Taxonomic Status ◽  
Human Infection ◽  
Influenza Viruses ◽  
Rt Pcr ◽  
Avian Influenza Viruses ◽  
Pcr Assay

Abstract Background In 2017–2018, a new highly pathogenic H5N6 avian influenza virus (AIV) variant appeared in poultry and wild birds in Asian and European countries and caused multiple outbreaks. These variant strains are different from the H5N6 virus associated with human infection in previous years, and their genetic taxonomic status and antigenicity have changed. Therefore, revision of the primers and probes of fluorescent RT-PCR is important to detect the new H5N6 subtype AIV in poultry and reduce the risk of an epidemic in birds or humans. Methods In this study, the primers and probes including three groups of HA and four groups of NA for H5N6 influenza virus were evaluated. Then a set of ideal primer and probes were selected to further optimize the reaction system and established a method of double rRT-PCR assay. The specificity of this method was determined by using H1~H16 subtype AIV. Results The results showed that fluorescence signals were obtained for H5 virus in FAM channel and N6 virus in VIC channel, and no fluorescent signal was observed in other subtypes of avian influenza viruses. The detection limit of this assay was 69 copies for H5 and 83 copies for N6 gene. And, the variability tests of intra- and inter-assay showed excellent reproducibility. Moreover, this assay showed 100% agreement with virus isolation method in detecting samples from poultry. Conclusion The duplex rRT-PCR assay presented here has high specificity, sensitivity and reproducibility, and can be used for laboratory surveillance and rapid diagnosis of newly emerged H5N6 subtype avian influenza viruses.

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