scholarly journals Mutations in PB2 and HA enhanced pathogenicity of H4N6 avian influenza virus in mice

2020 ◽  
Vol 101 (9) ◽  
pp. 910-920 ◽  
Author(s):  
Guanlong Xu ◽  
Fang Wang ◽  
Qiuchen Li ◽  
Guoxia Bing ◽  
Shijie Xie ◽  
...  
Keyword(s):  
Public Health ◽  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Point Mutations ◽  
Polymerase Activity ◽  
Potential Threat ◽  
Gain Adaptation

The H4 subtype avian influenza virus (AIV) continues to circulate in both wild birds and poultry, and occasionally infects mammals (e.g. pigs). H4-specific antibodies have also been detected in poultry farm workers, which suggests that H4 AIV poses a potential threat to public health. However, the molecular mechanism by which H4 AIVs could gain adaptation to mammals and whether this has occurred remain largely unknown. To better understand this mechanism, an avirulent H4N6 strain (A/mallard/Beijing/21/2011, BJ21) was serially passaged in mice and mutations were characterized after passaging. A virulent mouse-adapted strain was generated after 12 passages, which was tentatively designated BJ21-MA. The BJ21-MA strain replicated more efficiently than the parental BJ21, both in vivo and in vitro. Molecular analysis of BJ21-MA identified four mutations, located in proteins PB2 (E158K and E627K) and HA (L331I and G453R, H3 numbering). Further studies showed that the introduction of E158K and/or E627K substitutions into PB2 significantly increased polymerase activity, which led to the enhanced replication and virulence of BJ21-MA. Although individual L331I or G453R substitutions in HA did not change the pathogenicity of BJ21 in mice, both mutations significantly enhanced virulence. In conclusion, our data presented in this study demonstrate that avian H4 virus can adapt to mammals by point mutations in PB2 or HA, which consequently poses a potential threat to public health.

A 113-amino-acid truncation at the NS1 C-terminus is a determinant for viral replication of H5N6 avian influenza virus in vitro and in vivo

2018 ◽  
Vol 225 ◽  
pp. 6-16 ◽  
Author(s):  
Xiaole Cui ◽  
Yanhong Ji ◽  
Zhengxiang Wang ◽  
Yingying Du ◽  
Haoran Guo ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Avian Influenza ◽  
Viral Replication ◽  
Avian Influenza Virus ◽  
C Terminus

scholarly journals A Unique Multibasic Proteolytic Cleavage Site and Three Mutations in the HA2 Domain Confer High Virulence of H7N1 Avian Influenza Virus in Chickens

2015 ◽  
Vol 90 (1) ◽  
pp. 400-411 ◽  
Author(s):  
El-Sayed M. Abdelwhab ◽  
Jutta Veits ◽  
Kerstin Tauscher ◽  
Mario Ziller ◽  
Jens P. Teifke ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Cleavage Site ◽  
Influenza Viruses ◽  
Highly Pathogenic ◽  
Systemic Spread ◽  
H7n1 Virus

ABSTRACT In 1999, after circulation for a few months in poultry in Italy, low-pathogenic (LP) avian influenza (AI) H7N1 virus mutated into a highly pathogenic (HP) form by acquisition of a unique multibasic cleavage site (mCS), PEIPKGSRVRR*GLF (asterisk indicates the cleavage site), in the hemagglutinin (HA) and additional alterations with hitherto unknown biological function. To elucidate these virulence-determining alterations, recombinant H7N1 viruses carrying specific mutations in the HA of LPAI A/chicken/Italy/473/1999 virus (Lp) and HPAI A/chicken/Italy/445/1999 virus (Hp) were generated. Hp with a monobasic CS or carrying the HA of Lp induced only mild or no disease in chickens, thus resembling Lp. Conversely, Lp with the HA of Hp was as virulent and transmissible as Hp. While Lp with a multibasic cleavage site (Lp_CS445) was less virulent than Hp, full virulence was exhibited when HA2 was replaced by that of Hp. In HA2, three amino acid differences consistently detected between LP and HP H7N1 viruses were successively introduced into Lp_CS445. Q450L in the HA2 stem domain increased virulence and transmission but was detrimental to replication in cell culture, probably due to low-pH activation of HA. A436T and/or K536R restored viral replication in vitro and in vivo . Viruses possessing A436T and K536R were observed early in the HPAI outbreak but were later superseded by viruses carrying all three mutations. Together, besides the mCS, stepwise mutations in HA2 increased the fitness of the Italian H7N1 virus in vivo . The shift toward higher virulence in the field was most likely gradual with rapid optimization. IMPORTANCE In 1999, after 9 months of circulation of low-pathogenic (LP) avian influenza virus (AIV), a devastating highly pathogenic (HP) H7N1 AIV emerged in poultry, marking the largest epidemic of AIV reported in a Western country. The HPAIV possessed a unique multibasic cleavage site (mCS) complying with the minimum motif for HPAIV. The main finding in this report is the identification of three mutations in the HA2 domain that are required for replication and stability, as well as for virulence, transmission, and tropism of H7N1 in chickens. In addition to the mCS, Q450L was required for full virulence and transmissibility of the virus. Nonetheless, it was detrimental to virus replication and required A436T and/or K536R to restore replication, systemic spread, and stability. These results are important for better understanding of the evolution of highly pathogenic avian influenza viruses from low-pathogenic precursors.

scholarly journals A Well-Defined H9N2 Avian Influenza Virus Genotype with High Adaption in Mammals was Prevalent in Chinese Poultry Between 2016 to 2019

Viruses ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 432 ◽  
Author(s):  
Zhaokun Chen ◽  
Qinghua Huang ◽  
Shaohua Yang ◽  
Shuai Su ◽  
Baoquan Li ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Mdck Cells ◽  
Replication Capacity ◽  
Virus Genotype ◽  
Influenza Pandemics ◽  
Mouse Lungs

H9N2 subtype avian influenza virus (AIV) is widely prevalent in poultry, and the virus is becoming adaptive to mammals, which poses pandemic importance. Here, BALB/c mice were employed as a model to evaluate the adaption in mammals of 21 field H9N2 viruses isolated from avian species between 2016 to 2019 in China. The replication capacity of the viruses was evaluated in the lungs of mice. The pathogenicity of the viruses were compared by weight loss and lung lesions from infected mice. The whole genomic sequences of the viruses were further characterized to define the associated phenotypes of the H9N2 viruses in vitro and in vivo. The results showed that most viruses could replicate well and cause lesions in the mouse lungs. The propagation capacity in MDCK cells and damage to respiratory tissues of the infected mice corresponded to relative viral titers in the mouse lungs. Further genome analysis showed that all of the H9N2 viruses belonged to the same genotype, G57, and contained a couple of amino acid substitutions or deletions that have been demonstrated as avian-human markers. Additionally, nine amino acids residues in seven viral proteins were found to be correlated with the replication phenotypes of the H9N2 viruses in mammals. The study demonstrated that a well-defined H9N2 AIV genotype with high adaption in mammals was prevalent in China in recent years. Further investigations on the role of the identified residues and continuous surveillance of newly identified mutations associated with host adaption should be strengthened to prevent any devastating human influenza pandemics.

scholarly journals Characterization of the In Vitro and In Vivo Efficacy of Baloxavir Marboxil against the H5 Highly Pathogenic Avian Influenza Virus Infection

2021 ◽  
Author(s):  
Keiichi Taniguchi ◽  
Yoshinori Ando ◽  
Masanori Kobayashi ◽  
Shinsuke Toba ◽  
Haruaki Nobori ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Highly Pathogenic Avian Influenza ◽  
Influenza Virus Infection ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Antiviral Efficacy ◽  
Pathogenic Avian Influenza Virus

Human infections with the H5 highly pathogenic avian influenza virus (HPAIV) sporadically threatens public health. The susceptibility of HPAIVs to baloxavir acid (BXA), which is a new class of inhibitor for the influenza virus cap-dependent endonuclease, has been confirmed in vitro, but has not yet been characterized fully. Here, the efficacy of BXA against HPAIVs, including recent H5N8 variants in vitro was assessed. The antiviral efficacy of baloxavir marboxil (BXM) in H5N1 virus-infected mice was also investigated. BXA exhibited similar in vitro activities against H5N1, H5N6, and H5N8 variants tested to those of seasonal and other zoonotic strains. BXM monotherapy in mice infected with the H5N1 HPAIV clinical isolate; A/Hong Kong/483/1997 (H5N1) strain, also caused a significant reduction in viral titers in the lungs, brains, and kidneys, followed by prevention of acute lung inflammation and improvement of mortality compared with oseltamivir phosphate (OSP). Furthermore, combination treatments with BXM and OSP, using a 48-hour delayed treatment model showed a more potent effect on viral replication in organs, accompanied by improved survival compared to BXM or OSP monotherapy. From each test, no resistant virus (e.g., I38T in the PA) emerged in any BXM-treated mouse. These results therefore support the conclusion that BXM has potent antiviral efficacy against H5 HPAIV infections.

scholarly journals Detection of avian influenza virus: a comparative study of the in silico and in vitro performances of current RT-qPCR assays

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andrea Laconi ◽  
Andrea Fortin ◽  
Giulia Bedendo ◽  
Akihiro Shibata ◽  
Yoshihiro Sakoda ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Comparative Study ◽  
Avian Influenza Virus ◽  
In Silico ◽  
Influenza Virus A

scholarly journals Genetic Characterization of Avian Influenza A (H11N9) Virus Isolated from Mandarin Ducks in South Korea in 2018

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 203
Author(s):  
Hien Thi Tuong ◽  
Ngoc Minh Nguyen ◽  
Haan Woo Sung ◽  
Hyun Park ◽  
Seon-Ju Yeo
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Avian Influenza ◽  
South Korea ◽  
Avian Influenza Virus ◽  
Influenza A ◽  
Sequence Similarity ◽  
Basic Amino Acid ◽  
Wild Birds

In July 2018, a novel avian influenza virus (A/Mandarin duck/South Korea/KNU18-12/2018(H11N9)) was isolated from Mandarin ducks in South Korea. Phylogenetic and molecular analyses were conducted to characterize the genetic origins of the H11N9 strain. Phylogenetic analysis indicated that eight gene segments of strain H11N9 belonged to the Eurasian lineages. Analysis of nucleotide sequence similarity of both the hemagglutinin (HA) and neuraminidase (NA) genes revealed the highest homology with A/duck/Kagoshima/KU57/2014 (H11N9), showing 97.70% and 98.00% nucleotide identities, respectively. Additionally, internal genes showed homology higher than 98% compared to those of other isolates derived from duck and wild birds. Both the polymerase acidic (PA) and polymerase basic 1 (PB1) genes were close to the H5N3 strain isolated in China; whereas, other internal genes were closely related to that of avian influenza virus in Japan. A single basic amino acid at the HA cleavage site (PAIASR↓GLF), the lack of a five-amino acid deletion (residue 69–73) in the stalk region of the NA gene, and E627 in the polymerase basic 2 (PB2) gene indicated that the A/Mandarin duck/South Korea/KNU18-12/2018(H11N9) isolate was a typical low-pathogenicity avian influenza. In vitro viral replication of H11N9 showed a lower titer than H1N1 and higher than H9N2. In mice, H11N9 showed lower adaptation than H1N1. The novel A/Mandarin duck/South Korea/KNU18-12/2018(H11N9) isolate may have resulted from an unknown reassortment through the import of multiple wild birds in Japan and Korea in approximately 2016–2017, evolving to produce a different H11N9 compared to the previous H11N9 in Korea (2016). Further reassortment events of this virus occurred in PB1 and PA in China-derived strains. These results indicate that Japanese- and Chinese-derived avian influenza contributes to the genetic diversity of A/Mandarin duck/South Korea/KNU18-12/2018(H11N9) in Korea.

scholarly journals Genetics, Receptor Binding, Replication, and Mammalian Transmission of H4 Avian Influenza Viruses Isolated from Live Poultry Markets in China

2015 ◽  
Vol 90 (3) ◽  
pp. 1455-1469 ◽  
Author(s):  
Libin Liang ◽  
Guohua Deng ◽  
Jianzhong Shi ◽  
Shuai Wang ◽  
Qianyi Zhang ◽  
...  
Keyword(s):  
Public Health ◽  
Influenza Virus ◽  
Avian Influenza ◽  
Receptor Binding ◽  
Guinea Pigs ◽  
Direct Contact ◽  
Potential Threat ◽  
The World ◽  
Live Poultry ◽  
Live Poultry Markets

ABSTRACTH4 avian influenza virus (AIV) is one of the most prevalent influenza virus subtypes in the world. However, whether H4 AIVs pose a threat to public health remains largely unclear. Here, we analyzed the phylogenetic relationships, receptor binding properties, replication, and transmissibility in mammals of H4 AIVs isolated from live poultry markets in China between 2009 and 2012. Genomic sequence analysis of 36 representative H4 viruses revealed 32 different genotypes, indicating that these viruses are undergoing complex and frequent reassortment events. All 32 viruses tested could replicate in the respiratory organs of infected mice without prior adaptation. Receptor binding analysis demonstrated that the H4 AIVs bound to α-2,6-linked glycans, although they retained the binding preference for α-2,3-linked glycans. When we tested the direct-contact transmission of 10 H4 viruses in guinea pigs, we found that three viruses did not transmit to any of the contact animals, one virus transmitted to one of three contact animals, and six viruses transmitted to all three contact animals. When we further tested the respiratory droplet transmissibility of four of the viruses that transmitted efficiently via direct contact, we found that three of them could transmit to one or two of the five exposed animals. Our study demonstrates that the current circulating H4 AIVs can infect, replicate in, and transmit to mammalian hosts, thereby posing a potential threat to human health. These findings emphasize the continual need for enhanced surveillance of H4 AIVs.IMPORTANCENumerous surveillance studies have documented the wide distribution of H4 AIVs throughout the world, yet the biological properties of H4 viruses have not been well studied. In this study, we found that multiple genotypes of H4 viruses are cocirculating in the live poultry markets of China and that H4 viruses can replicate in mice, possess human-type receptor binding specificity, and transmit between guinea pigs via direct contact. Strikingly, some H4 strains also can transmit via respiratory droplet, albeit with limited efficiency. These results clearly show the potential threat posed by H4 viruses to public health.

scholarly journals The NS Segment of an H5N1 Highly Pathogenic Avian Influenza Virus (HPAIV) Is Sufficient To Alter Replication Efficiency, Cell Tropism, and Host Range of an H7N1 HPAIV

2009 ◽  
Vol 84 (4) ◽  
pp. 2122-2133 ◽  
Author(s):  
Wenjun Ma ◽  
Dominique Brenner ◽  
Zhongfang Wang ◽  
Bianca Dauber ◽  
Christina Ehrhardt ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Host Range ◽  
Highly Pathogenic Avian Influenza ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Primary Mouse ◽  
Pathogenic Avian Influenza Virus

ABSTRACT A reassortant avian influenza virus (designated FPV NS GD), carrying the NS-segment of the highly pathogenic avian influenza virus (HPAIV) strain A/Goose/Guangdong/1/96 (GD; H5N1) in the genetic background of the HPAIV strain A/FPV/Rostock/34 (FPV; H7N1), was rescued by reverse genetics. Remarkably, in contrast to the recombinant wild-type FPV (rFPV), the reassortant virus was able to replicate more efficiently in different human cell lines and primary mouse epithelia cells without prior adaptation. Moreover, FPV NS GD caused disease and death in experimentally infected mice and was detected in mouse lungs; in contrast, rFPV was not able to replicate in mice effectively. These results indicated an altered host range and increased virulence. Furthermore FPV NS GD showed pronounced pathogenicity in chicken embryos. In an attempt to define the molecular basis for the apparent differences, we determined that NS1 proteins of the H5N1 and H7N1 strains bound the antiviral kinase PKR and the F2F3 domain of cleavage and polyadenylation specificity factor 30 (CPSF30) with comparable efficiencies in vitro. However, FPV NS GD infection resulted in (i) increased expression of NS1, (ii) faster and stronger PKR inhibition, and (iii) stronger beta interferon promoter inhibition than rFPV. Taken together, the results shed further light on the importance of the NS segment of an H5N1 strain for viral replication, molecular pathogenicity, and host range of HPAIVs and the possible consequences of a reassortment between naturally occurring H7 and H5 type HPAIVs.

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