scholarly journals Characteristics of Avian Influenza H9N2 Virus Isolated from Humans and its Seroprevalence Among Occupationally Exposed Populations in China

2021 ◽  
Author(s):  
Jie Dong ◽  
Hong Bo ◽  
Libo Dong ◽  
Ye Zhang ◽  
Weijuan Huang ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Receptor Binding ◽  
H9n2 Virus ◽  
Antigenic Drift ◽  
Antigenic Analysis ◽  
H9n2 Influenza Virus ◽  
Binding Preference ◽  
Significant Difference ◽  
Occupationally Exposed ◽  
Human Infections

Abstract Background: The first human-infected H9N2 influenza case can be traced back to 1998. Although the H9N2 influenza virus has low pathogenicity in animals, it donated partial or whole cassettes of internal genes to reassort novel viruses, such as H7N9, H10N8 and H5N6 viruses, that caused human infections with high fatality. Since 2013, sporadic but increasingly frequent human cases caused by H9N2 influenza virus have been confirmed globally, and most of them were from China. Methods: Information on human infections with H9N2 influenza virus was collected. Viral molecular determinants were determined by deep sequencing, and phylogenetic analysis was performed using MEGA 6.06. Antigenic analysis was performed by a hemagglutination inhibition (HI) assay. Receptor binding preference analysis was conducted based on a solid-phase binding assay with synthetic sialylglycopolymers. Antiviral susceptibility was determined by a fluorescence-based neuraminidase (NA) inhibition assay. Serological study of occupationally exposed populations was performed by HI assay screening and confirmed by microneutralization assay.Results: From 2013 to 2018, 33 human H9N2cases were reported in China, among them 75.7% were children under 10 years old .The 22 viruses were isolated and concentrated in the Y280/G9 lineage of the HA and NA genes. All human H9N2 viruses belonged to the Y280/G9 antigenic lineage, presented a human-like receptor binding preference and remained susceptible to NA inhibitors, but most demonstrated resistance to M2 inhibitors. The seroprevalence of occupationally exposed populations was 2.15%, 3.17%, 2.93% and 1.54% from 2015 to 2018, respectively. A significant difference in seroprevalence was shown between provinces with human cases (3.66%) and provinces without human cases (2.18%). Conclusions: The continuous antigenic drift and human-like receptor binding preference of the H9N2 virus enable it to have a high risk of causing human infections. The status of the seropositivity in occupationally exposed populations implies a substantial threat to public health. Research on human infection with H9N2 influenza virus should be strengthened to monitor the emergence of sustainable human-to-human transmission and the possibility of an endemic or a pandemic related to it.

scholarly journals A PB1-K577E Mutation in H9N2 Influenza Virus Increases Polymerase Activity and Pathogenicity in Mice

Viruses ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 653 ◽  
Author(s):  
Haruhiko Kamiki ◽  
Hiromichi Matsugo ◽  
Tomoya Kobayashi ◽  
Hiroho Ishida ◽  
Akiko Takenaka-Uema ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Novel Mutation ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
H9n2 Virus ◽  
Wild Type Virus ◽  
H9n2 Influenza Virus ◽  
Pathogenicity Determinant ◽  
Lower Temperature ◽  
Human Infections

H9N2 avian influenza viruses are present in poultry worldwide. These viruses are considered to have pandemic potential, because recent isolates can recognize human-type receptor and several sporadic human infections have been reported. In this study, we aimed to identify mutations related to mammalian adaptation of H9N2 influenza virus. We found that mouse-adapted viruses had several mutations in hemagglutinin (HA), PB2, PA, and PB1. Among the detected mutations, PB1-K577E was a novel mutation that had not been previously reported to involve mammalian adaptation. A recombinant H9N2 virus bearing only the PB1-K577E mutation showed enhanced pathogenicity in mice, with increased virus titers in nasal turbinates compared to that in mice infected with the wild-type virus. In addition, the PB1-K577E mutation increased virus polymerase activity in human cell culture at a lower temperature. These data suggest that the PB1-K577E mutation is a novel pathogenicity determinant of H9N2 virus in mice and could be a signature for mammalian adaptation.

scholarly journals Generation and characterization of variants of NWS/G70C influenza virus after in vitro passage in 4-amino-Neu5Ac2en and 4-guanidino-Neu5Ac2en.

1996 ◽  
Vol 40 (1) ◽  
pp. 40-46 ◽  
Author(s):  
J L McKimm-Breschkin ◽  
T J Blick ◽  
A Sahasrabudhe ◽  
T Tiong ◽  
D Marshall ◽  
...  
Keyword(s):  
Amino Acids ◽  
Influenza Virus ◽  
Receptor Binding ◽  
Liquid Culture ◽  
Plaque Assay ◽  
Enoic Acid ◽  
Cross Resistance ◽  
Receptor Binding Site ◽  
Significant Difference

The compounds 4-amino-Neu5Ac2en (5-acetylamino-2,6-anhydro-4-amino-3,4,5- trideoxy-D-glycerol-D-galacto-non-2-enoic acid) and 4-guanidino-Neu5Ac2en (5-acetylamino-2,6-anhydro-4-guanidino-3,4,5- trideoxy-D-glycerol-D-galacto-non-2-enoic acid), which selectively inhibit the influenza virus neuraminidase, have been tested in vitro for their ability to generate drug-resistant variants. NWS/G70C virus (H1N9) was cultured in each drug by limiting-dilution passaging. After five or six passages in either compound, there emerged viruses which had a reduced sensitivity to the inhibitors in cell culture. Variant viruses were up to 1,000-fold less sensitive in plaque assays, liquid culture, and a hemagglutination-elution assay. In addition, cross-resistance to both compounds was seen in all three assays. Some isolates demonstrated drug dependence with an increase in both size and number of plaques in a plaque assay and an increase in virus yield in liquid culture in the presence of inhibitors. No significant difference in neuraminidase enzyme activity was detected in vitro, and no sequence changes in the conserved sites of the neuraminidase were found. However, changes in conserved amino acids in the hemagglutinin were detected. These amino acids were associated with either the hemagglutinin receptor binding site, Thr-155, or the left edge of the receptor binding pocket, Val-223 and Arg-229. Hence, mutations at these sites could be expected to affect the affinity or specificity of the hemagglutinin binding. Compensating mutations resulting in a weakly binding hemagglutinin thus seem to be circumventing the inhibition of the neuraminidase by allowing the virus to be released from cells with less dependence on the neuraminidase.

scholarly journals Structural and Functional Analysis of Surface Proteins from an A(H3N8) Influenza Virus Isolated from New England Harbor Seals

2014 ◽  
Vol 89 (5) ◽  
pp. 2801-2812 ◽  
Author(s):  
Hua Yang ◽  
Ha T. Nguyen ◽  
Paul J. Carney ◽  
Zhu Guo ◽  
Jessie C. Chang ◽  
...  
Keyword(s):  
Influenza Virus ◽  
New England ◽  
Receptor Binding ◽  
Influenza Virus Infection ◽  
Influenza Viruses ◽  
Surface Proteins ◽  
Harbor Seals ◽  
Binding Studies ◽  
Binding Preference ◽  
Major Surface

ABSTRACTIn late 2011, an A(H3N8) influenza virus infection resulted in the deaths of 162 New England harbor seals. Virus sequence analysis and virus receptor binding studies highlighted potential markers responsible for mammalian adaptation and a mixed receptor binding preference (S. J. Anthony, J. A. St Leger, K. Pugliares, H. S. Ip, J. M. Chan, Z. W. Carpenter, I. Navarrete-Macias, M. Sanchez-Leon, J. T. Saliki, J. Pedersen, W. Karesh, P. Daszak, R. Rabadan, T. Rowles, W. I. Lipkin, MBio 3:e00166-00112, 2012,http://dx.doi.org/10.1128/mBio.00166-12). Here, we present a detailed structural and biochemical analysis of the surface antigens of the virus. Results obtained with recombinant proteins for both the hemagglutinin and neuraminidase indicate a true avian receptor binding preference. Although the detection of this virus in new species highlights an increased potential for cross-species transmission, our results indicate that the A(H3N8) virus currently poses a low risk to humans.IMPORTANCECross-species transmission of zoonotic influenza viruses increases public health concerns. Here, we report a molecular and structural study of the major surface proteins from an A(H3N8) influenza virus isolated from New England harbor seals. The results improve our understanding of these viruses as they evolve and provide important information to aid ongoing risk assessment analyses as these zoonotic influenza viruses continue to circulate and adapt to new hosts.

scholarly journals Autophagy is involved in the replication of H9N2 influenza virus via the regulation of oxidative stress in alveolar epithelial cells

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Rui-hua Zhang ◽  
Hong-liang Zhang ◽  
Pei-yao Li ◽  
Chun-hong Li ◽  
Jing-ping Gao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Influenza Virus ◽  
Western Blot ◽  
Viral Replication ◽  
H9n2 Virus ◽  
Viral Titer ◽  
Oxygen Species ◽  
H9n2 Influenza Virus ◽  
And Oxidative Stress

Abstract Background Oxidative stress is an important pathogenic factor in influenza A virus infection. It has been found that reactive oxygen species induced by the H9N2 influenza virus is associated with viral replication. However, the mechanisms involved remain to be elucidated. Methods In this study, the role of autophagy was investigated in H9N2 influenza virus-induced oxidative stress and viral replication in A549 cells. Autophagy induced by H9N2 was inhibited by an autophagy inhibitor or RNA interference, the autophagy level, viral replication and the presence of oxidative stress were detected by western blot, TCID50 assay, and Real-time PCR. Then autophagy and oxidative stress were regulated, and viral replication was determined. At last, the Akt/TSC2/mTOR signaling pathways was detected by western blot. Results Autophagy was induced by the H9N2 influenza virus and the inhibition of autophagy reduced the viral titer and the expression of nucleoprotein and matrix protein. The blockage of autophagy suppressed the H9N2 virus-induced increase in the presence of oxidative stress, as evidenced by decreased reactive oxygen species production and malonaldehyde generation, and increased superoxide dismutase 1 levels. The changes in the viral titer and NP mRNA level caused by the antioxidant, N-acetyl-cysteine (NAC), and the oxidizing agent, H2O2, confirmed the involvement of oxidative stress in the control of viral replication. NAC plus transfection with Atg5 siRNA significantly reduced the viral titer and oxidative stress compared with NAC treatment alone, which confirmed that autophagy was involved in the replication of H9N2 influenza virus by regulating oxidative stress. Our data also revealed that autophagy was induced by the H9N2 influenza virus through the Akt/TSC2/mTOR pathway. The activation of Akt or the inhibition of TSC2 suppressed the H9N2 virus-induced increase in the level of LC3-II, restored the decrease in the expression of phospho-pAkt, phospho-mTOR and phospho-pS6 caused by H9N2 infection, suppressed the H9N2-induced increase in the presence of oxidative stress, and resulted in a decrease in the viral titer. Conclusion Autophagy is involved in H9N2 virus replication by regulating oxidative stress via the Akt/TSC2/mTOR signaling pathway. Thus, autophagy maybe a target which may be used to improve antiviral therapeutics.

scholarly journals Polymerase acidic subunit of H9N2 polymerase complex induces cell apoptosis by binding to PDCD 7 in A549 cells

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Shaohua Wang ◽  
Na Li ◽  
Shugang Jin ◽  
Ruihua Zhang ◽  
Tong Xu
Keyword(s):  
Cell Death ◽  
Influenza Virus ◽  
Cell Apoptosis ◽  
Influenza A ◽  
A549 Cells ◽  
Influenza Virus Infection ◽  
H9n2 Virus ◽  
Poultry Production ◽  
H9n2 Influenza Virus

Abstract Background H9N2 influenza virus, a subtype of influenza A virus, can spread across different species and induce the respiratory infectious disease in humans, leading to a severe public health risk and a huge economic loss to poultry production. Increasing studies have shown that polymerase acidic (PA) subunit of RNA polymerase in ribonucleoproteins complex of H9N2 virus involves in crossing the host species barriers, the replication and airborne transmission of H9N2 virus. Methods Here, to further investigate the role of PA subunit during the infection of H9N2 influenza virus, we employed mass spectrometry (MS) to search the potential binding proteins of PA subunit of H9N2 virus. Our MS results showed that programmed cell death protein 7 (PDCD7) is a binding target of PA subunit. Co-immunoprecipitation and pull-down assays further confirmed the interaction between PDCD7 and PA subunit. Overexpression of PA subunit in A549 lung cells greatly increased the levels of PDCD7 in the nuclear and induced cell death assayed by MTT assay. Results Flow cytometry analysis and Western blot results showed that PA subunit overexpression significantly increased the expression of pro-apoptotic protein, bax and caspase 3, and induced cell apoptosis. However, knockout of PDCD7 effectively attenuated the effects of PA overexpression in cell apoptosis. Conclusions In conclusion, the PA subunit of H9N2 virus bind with PDCD7 and regulated cell apoptosis, which provide new insights in the role of PA subunit during H9N2 influenza virus infection.

scholarly journals Two amino acid substitutions in the haemagglutinin of the 2009 pandemic H1N1 virus decrease direct-contact transmission in guinea pigs

2014 ◽  
Vol 95 (12) ◽  
pp. 2612-2617 ◽  
Author(s):  
Liang He ◽  
Kaijun Jiang ◽  
Qiwen Wu ◽  
Zhiqiang Duan ◽  
Haixu Xu ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Receptor Binding ◽  
Guinea Pigs ◽  
Direct Contact ◽  
Influenza A ◽  
Influenza Pandemic ◽  
H1n1 Influenza ◽  
Pandemic H1n1 ◽  
Binding Preference ◽  
Contact Transmission

The 2009 pandemic H1N1 influenza A virus spread across the globe and caused the first influenza pandemic of the 21st century. Many of the molecular factors that contributed to the airborne transmission of this pandemic virus have been determined; however, the direct-contact transmission of this virus remains poorly understood. In this study, we report that a combination of two mutations (N159D and Q226R) in the haemagglutinin (HA) protein of the representative 2009 H1N1 influenza virus A/California/04/2009 (CA04) caused a switch in receptor binding preference from the α2,6-sialoglycan to the α2,3-sialoglycan receptor, and decreased the binding intensities for both glycans. In conjunction with a significantly decreased replication efficiency in the nasal epithelium, this limited human receptor binding affinity resulted in inefficient direct-contact transmission of CA04 between guinea pigs. Our findings highlight the role of the HA gene in the transmission of the influenza virus.

scholarly journals Reassortment with dominant chicken H9N2 influenza virus contributed to the fifth H7N9 virus human epidemic

2021 ◽  
Author(s):  
Juan Pu ◽  
Yanbo Yin ◽  
Jiyu Liu ◽  
Xinyu Wang ◽  
Yong Zhou ◽  
...  
Keyword(s):  
Public Health ◽  
Influenza Virus ◽  
Influenza Viruses ◽  
H9n2 Virus ◽  
Close Monitoring ◽  
H7n9 Virus ◽  
Virus Genotype ◽  
H9n2 Influenza Virus ◽  
Adaptive Mutations ◽  
Viral Genes

H9N2 Avian influenza virus (AIV) is regarded as a principal donor of viral genes through reassortment to co-circulating influenza viruses that can result in zoonotic reassortants. Whether H9N2 virus can maintain sustained evolutionary impact on such reassortants is unclear. Since 2013, avian H7N9 virus had caused five sequential human epidemics in China; the fifth wave in 2016-2017 was by far the largest but the mechanistic explanation behind the scale of infection is not clear. Here, we found that, just prior to the fifth H7N9 virus epidemic, H9N2 viruses had phylogenetically mutated into new sub-clades, changed antigenicity and increased its prevalence in chickens vaccinated with existing H9N2 vaccines. In turn, the new H9N2 virus sub-clades of PB2 and PA genes, housing mammalian adaptive mutations, were reassorted into co-circulating H7N9 virus to create a novel dominant H7N9 virus genotype that was responsible for the fifth H7N9 virus epidemic. H9N2-derived PB2 and PA genes in H7N9 virus conferred enhanced polymerase activity in human cells at 33°C and 37°C, and increased viral replication in the upper and lower respiratory tracts of infected mice which could account for the sharp increase in human cases of H7N9 virus infection in the 2016-2017 epidemic. The role of H9N2 virus in the continual mutation of H7N9 virus highlights the public health significance of H9N2 virus in the generation of variant reassortants of increasing zoonotic potential. IMPORTANCE Avian H9N2 influenza virus, although primarily restricted to chicken populations, is a major threat to human public health by acting as a donor of variant viral genes through reassortment to co-circulating influenza viruses. We established that the high prevalence of evolving H9N2 virus in vaccinated flocks played a key role, as donor of new sub-clade PB2 and PA genes in the generation of a dominant H7N9 virus genotype (G72) with enhanced infectivity in humans during the 2016-2017 N7N9 virus epidemic. Our findings emphasize that the ongoing evolution of prevalent H9N2 virus in chickens is an important source, via reassortment, of mammalian adaptive genes for other influenza virus subtypes. Thus, close monitoring of prevalence and variants of H9N2 virus in chicken flocks is necessary in the detection of zoonotic mutations.

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