scholarly journals Intranasal Immunization with the Influenza A Virus Encoding Truncated NS1 Protein Protects Mice from Heterologous Challenge by Restraining the Inflammatory Response in the Lungs

2021 ◽  
Vol 9 (4) ◽  
pp. 690
Author(s):  
Kirill Vasilyev ◽  
Anna-Polina Shurygina ◽  
Maria Sergeeva ◽  
Marina Stukova ◽  
Andrej Egorov
Keyword(s):  
Influenza A ◽  
Cellular Response ◽  
Viral Vectors ◽  
Influenza Viruses ◽  
Innate Immune ◽  
H3n2 Virus ◽  
Control Group ◽  
Ns1 Protein ◽  
Intranasal Immunization ◽  
Heterologous Challenge

Influenza viruses with an impaired NS1 protein are unable to antagonize the innate immune system and, therefore, are highly immunogenic because of the self-adjuvating effect. Hence, NS1-mutated viruses are considered promising candidates for the development of live-attenuated influenza vaccines and viral vectors for intranasal administration. We investigated whether the immunogenic advantage of the virus expressing only the N-terminal half of the NS1 protein (124 a.a.) can be translated into the induction of protective immunity against a heterologous influenza virus in mice. We found that immunization with either the wild-type A/PR/8/34 (H1N1) influenza strain (A/PR8/NSfull) or its NS1-shortened counterpart (A/PR8/NS124) did not prevent the viral replication in the lungs after the challenge with the A/Aichi/2/68 (H3N2) virus. However, mice immunized with the NS1-shortened virus were better protected from lethality after the challenge with the heterologous virus. Besides showing the enhanced influenza-specific CD8+ T-cellular response in the lungs, immunization with the A/PR8/NS124 virus resulted in reduced concentrations of proinflammatory cytokines and the lower extent of leukocyte infiltration in the lungs after the challenge compared to A/PR8/NSfull or the control group. The data show that intranasal immunization with the NS1-truncated virus may better induce not only effector T-cells but also certain immunoregulatory mechanisms, reducing the severity of the innate immune response after the heterologous challenge.

scholarly journals Dual R108K and G189D Mutations in the NS1 Protein of A/H1N1 Influenza Virus Counteract Host Innate Immune Responses

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 905
Author(s):  
Meng-Ting Huang ◽  
Sen Zhang ◽  
Ya-Nan Wu ◽  
Wei Li ◽  
Yu-Chang Li ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Nonstructural Protein ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Innate Immune ◽  
Ns1 Protein ◽  
H1n1 Influenza Virus ◽  
Functional Sites ◽  
Nonstructural Protein 1

Influenza A viruses (IAV) modulate host antiviral responses to promote growth and pathogenicity. Here, we examined the multifunctional IAV nonstructural protein 1 (NS1) of influenza A virus to better understand factors that contribute to viral replication efficiency or pathogenicity. In 2009, a pandemic H1N1 IAV (A/California/07/2009 pH1N1) emerged in the human population from swine. Seasonal variants of this virus are still circulating in humans. Here, we compared the sequence of a seasonal variant of this H1N1 influenza virus (A/Urumqi/XJ49/2018(H1N1), first isolated in 2018) with the pandemic strain A/California/07/2009. The 2018 virus harbored amino acid mutations (I123V and N205S) in important functional sites; however, 108R and 189G were highly conserved between A/California/07/2009 and the 2018 variant. To better understand interactions between influenza viruses and the human innate immune system, we generated and rescued seasonal 2009 H1N1 IAV mutants expressing an NS1 protein harboring a dual mutation (R108K/G189D) at these conserved residues and then analyzed its biological characteristics. We found that the mutated NS1 protein exhibited systematic and selective inhibition of cytokine responses via a mechanism that may not involve binding to cleavage and polyadenylation specificity factor 30 (CPSF30). These results highlight the complexity underlying host–influenza NS1 protein interactions.

scholarly journals Inhibition of host innate immune responses and pathogenicity of recombinant Newcastle disease viruses expressing NS1 genes of influenza A viruses

2010 ◽  
Vol 91 (8) ◽  
pp. 1996-2001 ◽  
Author(s):  
Shin-Hee Kim ◽  
Siba K. Samal
Keyword(s):  
Immune Responses ◽  
Newcastle Disease ◽  
Influenza A ◽  
Rna Binding ◽  
Mutational Analysis ◽  
Influenza Viruses ◽  
Innate Immune ◽  
Ns1 Protein ◽  
Innate Immune Responses ◽  
Influenza A Viruses

The NS1 protein has been associated with the virulence of influenza A viruses. To evaluate the role of the NS1 protein in pathogenicity of pandemic H5N1 avian influenza and H1N1 2009 influenza viruses, recombinant Newcastle disease viruses (rNDVs) expressing NS1 proteins were generated. Expression of the NS1 proteins resulted in inhibition of host innate immune responses (beta interferon and protein kinase R production). In addition, the NS1 proteins were localized predominantly in the nucleus of virus-infected cells. Consequently, expression of the NS1 protein contributed to an increase in pathogenicity of rNDV in chickens. In particular, mutational analysis of H5N1 NS1 protein indicated that both the RNA-binding and effector domains affect virus pathogenicity synergistically. Our study also demonstrated that expression of H1N1/09 NS1 resulted in enhanced replication of rNDV in human cells, indicating that function of the NS1 proteins can be host-species-specific.

scholarly journals NS1 Protein of 2009 Pandemic Influenza A Virus Inhibits Porcine NLRP3 Inflammasome-Mediated Interleukin-1 Beta Production by Suppressing ASC Ubiquitination

2018 ◽  
Vol 92 (8) ◽  
Author(s):  
Hong-Su Park ◽  
GuanQun Liu ◽  
Sathya N. Thulasi Raman ◽  
Shelby L. Landreth ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Nlrp3 Inflammasome ◽  
Influenza A ◽  
Adaptor Protein ◽  
Influenza Viruses ◽  
Innate Immune ◽  
Inflammasome Activation ◽  
Pandemic H1n1 ◽  
Ns1 Protein ◽  
C Terminus

ABSTRACT The inflammasome represents a molecular platform for innate immune regulation and controls proinflammatory cytokine production. The NLRP3 inflammasome is comprised of NLRP3, ASC, and procaspase-1. When the NLRP3 inflammasome is activated, it causes ASC speck formation and caspase-1 activation, resulting in the maturation of interleukin-1β (IL-1β). The NLRP3 inflammasome is regulated at multiple levels, with one level being posttranslational modification. Interestingly, ubiquitination of ASC has been reported to be indispensable for the activation of the NLRP3 inflammasome. Influenza A virus (IAV) infection induces NLRP3 inflammasome-dependent IL-1β secretion, which contributes to the host antiviral defense. However, IAVs have evolved multiple antagonizing mechanisms, one of which is executed by viral NS1 protein to suppress the NLRP3 inflammasome. In this study, we compared IL-1β production in porcine alveolar macrophages in response to IAV infection and found that the 2009 pandemic H1N1 induced less IL-1β than swine influenza viruses (SIVs). Further study revealed that the NS1 C terminus of pandemic H1N1 but not that of SIV was able to significantly inhibit NLRP3 inflammasome-mediated IL-1β production. This inhibitory function was attributed to impaired ASC speck formation and suppression of ASC ubiquitination. Moreover, we identified two target lysine residues, K110 and K140, which are essential for both porcine ASC ubiquitination and NLRP3 inflammasome-mediated IL-1β production. These results revealed a novel mechanism by which the NS1 protein of the 2009 pandemic H1N1 suppresses NLRP3 inflammasome activation. IMPORTANCE Influenza A virus (IAV) infection activates the NLRP3 inflammasome, resulting in the production of IL-1β, which contributes to the host innate immune response. ASC, an adaptor protein of NLRP3, forms specks that are critical for inflammasome activation. Here, we report that the NS1 C terminus of the 2009 pandemic H1N1 has functions to suppress porcine IL-1β production by inhibiting ASC speck formation and ASC ubiquitination. Furthermore, the ubiquitination sites on porcine ASC were identified. The information gained here may contribute to an in-depth understanding of porcine inflammasome activation and regulation in response to different IAVs, helping to further enhance our knowledge of innate immune responses to influenza virus infection in pigs.

scholarly journals MOLECULAR AND GENETIC CHARACTERISTICS OF SURFACE AND NONSTRUCTURE PROTEINS OF PANDEMIC INFLUENZA VIRUSES A(H1N1)PDM09 IN 2015-2016 EPIDEMIC SEASON

2016 ◽  
Vol 72 (2) ◽  
pp. 44-48
Author(s):  
O. Smutko ◽  
L. Radchenko ◽  
A. Mironenko
Keyword(s):  
Amino Acid ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Phylogenetic Trees ◽  
Influenza Viruses ◽  
Amino Acid Substitutions ◽  
Ns1 Protein ◽  
Genetic Characteristics ◽  
Epidemic Season ◽  
Influenza A H1n1

The aim of the present study was identifying of molecular and genetic changes in hemaglutinin (HA), neuraminidase (NA) and non-structure protein (NS1) genes of pandemic influenza A(H1N1)pdm09 strains, that circulated in Ukraine during 2015-2016 epidemic season. Samples (nasopharyngeal swabs from patients) were analyzed using real-time polymerase chain reaction (RTPCR). Phylogenetic trees were constructed using MEGA 7 software. 3D structures were constructed in Chimera 1.11.2rc software. Viruses were collected in 2015-2016 season fell into genetic group 6B and in two emerging subgroups, 6B.1 and 6B.2 by gene of HA and NA. Subgroups 6B.1 and 6B.2 are defined by the following amino acid substitutions. In the NS1 protein were identified new amino acid substitutions D2E, N48S, and E125D in 2015-2016 epidemic season. Specific changes were observed in HA protein antigenic sites, but viruses saved similarity to vaccine strain. NS1 protein acquired substitution associated with increased virulence of the influenza virus.

scholarly journals Human Interferon Inducible Transmembrane Protein 3 (IFITM3) Inhibits Influenza Virus A Replication and Inflammation by Interacting with ABHD16A

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Liang Chen ◽  
Limei Zhu ◽  
Jun Chen
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Transmembrane Protein ◽  
Influenza Viruses ◽  
Expression Level ◽  
Hek293 Cells ◽  
Human Interferon ◽  
Control Group ◽  
Mrna Levels ◽  
Membrane Area

Studies have shown that human interferon inducible transmembrane protein (hIFITMs) family proteins have broad-spectrum antiviral capabilities. Preliminary studies in our laboratory have tentatively proved that hIFITMs have the effect of inhibiting influenza viruses. In order to further study its mechanism and role in the occurrence and development of influenza A, relevant studies have been carried out. Fluorescence quantitative polymerase chain reaction (PCR) detection technology was used to observe the effect of hIFITM3 on the replication of influenza A virus (IVA) and the interaction with hABHD16A. In HEK293 cells, overexpression of hIFITM3 protein significantly inhibited the replication of IVA at 24 h, 48 h, and 72 h; yeast two-hybrid experiment proved that hIFITM3 interacts with hABHD16A; laser confocal microscopy observations showed that hIFITM3 and hABHD16A colocalized in the cell membrane area; the expression level of inflammation-related factors in cells overexpressing hIFITM3 or hABHD16A was detected by fluorescence quantitative PCR, and the results showed that the mRNA levels of interleukin- (IL-) 1β, IL-6, IL-10, tumor necrosis factor- (TNF-) α, and cyclooxygenase 2 (COX2) were significantly increased. But when hIFITM3/hABHD16A was coexpressed, the mRNA expression levels of these cytokines were significantly reduced except COX2. When influenza virus infected cells coexpressing hIFITM3/hABHD16A, the expression level of inflammatory factors decreased compared with the control group, indicating that hIFITM3 can play an important role in regulating inflammation balance. This study confirmed that hIFITM3 has an effect of inhibiting IVA replication. Furthermore, it was found that hIFITM3 interacts with hABHD16A, following which it can better inhibit the replication of influenza virus and the inflammatory response caused by the disease process.

scholarly journals Defective RNA Replication and Late Gene Expression in Temperature-Sensitive Influenza Viruses Expressing Deleted Forms of the NS1 Protein

2004 ◽  
Vol 78 (8) ◽  
pp. 3880-3888 ◽  
Author(s):  
Ana M. Falcón ◽  
Rosa M. Marión ◽  
Thomas Zürcher ◽  
Paulino Gómez ◽  
Agustín Portela ◽  
...  
Keyword(s):  
Influenza A ◽  
Influenza Viruses ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Ns1 Protein ◽  
Late Gene Expression ◽  
Infected Cells ◽  
Defective Rna ◽  
Nucleocytoplasmic Export

ABSTRACT Influenza A virus mutants expressing C-terminally deleted forms of the NS1 protein (NS1-81 and NS1-110) were generated by plasmid rescue. These viruses were temperature sensitive and showed a small plaque size at the permissive temperature. The accumulation of virion RNA in mutant virus-infected cells was reduced at the restrictive temperature, while the accumulation of cRNA or mRNA was not affected, indicating that the NS1 protein is involved in the control of transcription versus replication processes in the infection. The synthesis and accumulation of late virus proteins were reduced in NS1-81 mutant-infected cells at the permissive temperature and were essentially abolished for both viruses at the restrictive temperature, while synthesis and accumulation of nucleoprotein (NP) were unaffected. Probably as a consequence, the nucleocytoplasmic export of virus NP was strongly inhibited at the restrictive temperature. These results indicate that the NS1 protein is essential for nuclear and cytoplasmic steps during the virus cycle.

scholarly journals Strong interferon-inducing capacity of a highly virulent variant of influenza A virus strain PR8 with deletions in the NS1 gene

2009 ◽  
Vol 90 (12) ◽  
pp. 2990-2994 ◽  
Author(s):  
Georg Kochs ◽  
Luis Martínez-Sobrido ◽  
Stefan Lienenklaus ◽  
Siegfried Weiss ◽  
Adolfo García-Sastre ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Viruses ◽  
Ns1 Protein ◽  
Efficient Induction ◽  
Ns1 Gene ◽  
Mouse Lungs ◽  
Highly Virulent ◽  
Complete Deletion

Influenza viruses lacking the interferon (IFN)-antagonistic non-structural NS1 protein are strongly attenuated. Here, we show that mutants of a highly virulent variant of A/PR/8/34 (H1N1) carrying either a complete deletion or C-terminal truncations of NS1 were far more potent inducers of IFN in infected mice than NS1 mutants derived from standard A/PR/8/34. Efficient induction of IFN correlated with successful initial virus replication in mouse lungs, indicating that the IFN response is boosted by enhanced viral activity. As the new NS1 mutants can be handled in standard biosafety laboratories, they represent convenient novel tools for studying virus-induced IFN expression in vivo.

scholarly journals Functional Replacement of the Carboxy-Terminal Two-Thirds of the Influenza A Virus NS1 Protein with Short Heterologous Dimerization Domains

2002 ◽  
Vol 76 (24) ◽  
pp. 12951-12962 ◽  
Author(s):  
Xiuyan Wang ◽  
Christopher F. Basler ◽  
Bryan R. G. Williams ◽  
Robert H. Silverman ◽  
Peter Palese ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Rna Binding ◽  
Influenza Viruses ◽  
Ns1 Protein ◽  
Wild Type ◽  
Dimerization Domain ◽  
Carboxy Terminal

ABSTRACT The NS1 protein of influenza A/WSN/33 virus is a 230-amino-acid-long protein which functions as an interferon alpha/beta (IFN-α/β) antagonist by preventing the synthesis of IFN during viral infection. In tissue culture, the IFN inhibitory function of the NS1 protein has been mapped to the RNA binding domain, the first 73 amino acids. Nevertheless, influenza viruses expressing carboxy-terminally truncated NS1 proteins are attenuated in mice. Dimerization of the NS1 protein has previously been shown to be essential for its RNA binding activity. We have explored the ability of heterologous dimerization domains to functionally substitute in vivo for the carboxy-terminal domains of the NS1 protein. Recombinant influenza viruses were generated that expressed truncated NS1 proteins of 126 amino acids, fused to 28 or 24 amino acids derived from the dimerization domains of either the Saccharomyces cerevisiae PUT3 or the Drosophila melanogaster Ncd (DmNcd) proteins. These viruses regained virulence and lethality in mice. Moreover, a recombinant influenza virus expressing only the first 73 amino acids of the NS1 protein was able to replicate in mice lacking three IFN-regulated antiviral enzymes, PKR, RNaseL, and Mx, but not in wild-type (Mx-deficient) mice, suggesting that the attenuation was mainly due to an inability to inhibit the IFN system. Remarkably, a virus with an NS1 truncated at amino acid 73 but fused to the dimerization domain of DmNcd replicated and was also highly pathogenic in wild-type mice. These results suggest that the main biological function of the carboxy-terminal region of the NS1 protein of influenza A virus is the enhancement of its IFN antagonist properties by stabilizing the NS1 dimeric structure.

scholarly journals H3N2 Virus as Causative Agent of ARDS Requiring Extracorporeal Membrane Oxygenation Support

2014 ◽  
Vol 2014 ◽  
pp. 1-3
Author(s):  
Adriano Peris ◽  
Giovanni Zagli ◽  
Pasquale Bernardo ◽  
Massimo Bonacchi ◽  
Morena Cozzolino ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Extracorporeal Membrane Oxygenation ◽  
Influenza A ◽  
Seasonal Influenza ◽  
Influenza Season ◽  
Influenza Viruses ◽  
H3n2 Virus ◽  
Membrane Oxygenation ◽  
Viral Aetiology ◽  
Increased Risk

Pandemic influenza virus A(H1N1) 2009 was associated with a higher risk of viral pneumonia in comparison with seasonal influenza viruses. The influenza season 2011-2012 was characterized by the prevalent circulation of influenza A(H3N2) viruses. Whereas most H3N2 patients experienced mild, self-limited influenza-like illness, some patients were at increased risk for influenza complications because of age or underlying medical conditions. Cases presented were patients admitted to the Intensive Care Unit (ICU) of ECMO referral center (Careggi Teaching Hospital, Florence, Italy). Despite extracorporeal membrane oxygenation treatment (ECMO), one patient with H3N2-induced ARDS did not survive. Our experience suggests that viral aetiology is becoming more important and hospitals should be able to perform a fast differential diagnosis between bacterial and viral aetiology.

scholarly journals Surveillance of influenza viruses isolated from travellers at Nagoya International Airport

2000 ◽  
Vol 124 (3) ◽  
pp. 507-514 ◽  
Author(s):  
K. SATO ◽  
T. MORISHITA ◽  
E. NOBUSAWA ◽  
Y. SUZUKI ◽  
Y. MIYAZAKI ◽  
...  
Keyword(s):  
Influenza A ◽  
Respiratory Symptoms ◽  
H1n1 Virus ◽  
Influenza Season ◽  
Influenza Viruses ◽  
H3n2 Virus ◽  
Influenza B ◽  
International Airport ◽  
Quarantine Station ◽  
Virus Strains

In order to conduct a survey of influenza viruses entering Japan via travellers arriving by airplanes, gargle solutions were collected from passengers who reported to the quarantine station of Nagoya International Airport complaining of respiratory symptoms. From 504 samples collected between August 1996 and March 1999, 30 influenza virus strains were isolated. Twenty-eight of the isolates were influenza A (H3N2) viruses and two were influenza B viruses. No H1N1 virus was isolated. Among 28 isolates of H3N2 virus, 3 strains were obtained outside the influenza season. Nucleotide sequences of the haemagglutinin (HA) genes of these isolates along with those from domestic patients were analysed in order to determine the influence of imported influenza viruses by travellers on epidemics in Japan. From the phylogenetic and chronological aspects, the possibility was suggested in one case in 1997/8 and two in the 1998/9 season that imported virus by travellers may have influenced the domestic influenza epidemics.

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