scholarly journals NSP protein encoded in negative NS RNA strand of influenza A virus induces cellular immune response in infected animals

2019 ◽  
Vol 486 (3) ◽  
pp. 389-394
Author(s):  
O. P. Zhirnov ◽  
E. I. Isaeva
Keyword(s):  
Immune Response ◽  
Amino Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Central Zone ◽  
Virus Genome ◽  
T Cell Epitopes ◽  
Influenza A Viruses ◽  
Protein Amino Acid ◽  
Cellular Immune

Infection of mice with influenza A viruses led to the formation of clones of lymphocytes that specifically recognizes viral domains in the central zone of the NSP protein (amino acid positions 83-119). Computer analysis of the primary structure of the NSP protein showed the presence of T-cell epitopes in the central part of the NSP molecule. The findings indicate that the viral NSP gene is expressed in the infected animals and support the concept of the bipolar strategy (ambisense strategy) of the influenza A virus genome.

scholarly journals Cellular immune response in infected mice to NSP protein encoded by the negative strand NS RNA of influenza A virus

2019 ◽  
Vol 6 (1) ◽  
pp. 28-36 ◽  
Author(s):  
Oleg P. Zhirnov ◽  
◽  
Tatyana E. Konakova ◽  
Darisuren Anhlan ◽  
Stephan Ludwig ◽  
...  
Keyword(s):  
Immune Response ◽  
Influenza A Virus ◽  
Cellular Immune Response ◽  
Influenza A ◽  
Negative Strand ◽  
Cellular Immune

scholarly journals Host factor Rab11a is critical for efficient assembly of influenza A virus genomic segments

2021 ◽  
Vol 17 (5) ◽  
pp. e1009517
Author(s):  
Julianna Han ◽  
Ketaki Ganti ◽  
Veeresh Kumar Sali ◽  
Carly Twigg ◽  
Yifeng Zhang ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Genome Assembly ◽  
Influenza A ◽  
Early Time ◽  
Virus Genome ◽  
Host Factor ◽  
Influenza A Viruses ◽  
Ribonucleoprotein Complexes ◽  
Microtubule Networks ◽  
Cellular Components

It is well documented that influenza A viruses selectively package 8 distinct viral ribonucleoprotein complexes (vRNPs) into each virion; however, the role of host factors in genome assembly is not completely understood. To evaluate the significance of cellular factors in genome assembly, we generated a reporter virus carrying a tetracysteine tag in the NP gene (NP-Tc virus) and assessed the dynamics of vRNP localization with cellular components by fluorescence microscopy. At early time points, vRNP complexes were preferentially exported to the MTOC; subsequently, vRNPs associated on vesicles positive for cellular factor Rab11a and formed distinct vRNP bundles that trafficked to the plasma membrane on microtubule networks. In Rab11a deficient cells, however, vRNP bundles were smaller in the cytoplasm with less co-localization between different vRNP segments. Furthermore, Rab11a deficiency increased the production of non-infectious particles with higher RNA copy number to PFU ratios, indicative of defects in specific genome assembly. These results indicate that Rab11a+ vesicles serve as hubs for the congregation of vRNP complexes and enable specific genome assembly through vRNP:vRNP interactions, revealing the importance of Rab11a as a critical host factor for influenza A virus genome assembly.

scholarly journals The CPSF30 Binding Site on the NS1A Protein of Influenza A Virus Is a Potential Antiviral Target

2006 ◽  
Vol 80 (8) ◽  
pp. 3957-3965 ◽  
Author(s):  
Karen Y. Twu ◽  
Diana L. Noah ◽  
Ping Rao ◽  
Rei-Lin Kuo ◽  
Robert M. Krug
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Influenza B Virus ◽  
Influenza B ◽  
Influenza A Viruses ◽  
B Virus ◽  
Ns1a Protein

ABSTRACT The emergence of influenza A viruses resistant to the two existing classes of antiviral drugs highlights the need for additional antiviral drugs, particularly considering the potential threat of a pandemic of H5N1 influenza A viruses. Here, we determine whether influenza A virus replication can be selectively inhibited by blocking the ability of its NS1A protein to inhibit the 3′-end processing of cellular pre-mRNAs, including beta interferon (IFN-β) pre-mRNA. Pre-mRNA processing is inhibited via the binding of the NS1A protein to the cellular CPSF30 protein, and mutational inactivation of this NS1A binding site causes severe attenuation of the virus. We demonstrate that binding of CPSF30 is mediated by two of its zinc fingers, F2F3, and that the CPSF30/F2F3 binding site on the NS1A protein extends from amino acid 144 to amino acid 186. We generated MDCK cells that constitutively express epitope-tagged F2F3 in the nucleus, although at only approximately one-eighth the level of the NS1A protein produced during virus infection. Influenza A virus replication was inhibited in this cell line, whereas no inhibition was observed with influenza B virus, whose NS1B protein lacks a binding site for CPSF30. Influenza A virus, but not influenza B virus, induced increased production of IFN-β mRNA in the F2F3-expressing cells. These results, which indicate that F2F3 inhibits influenza A virus replication by blocking the binding of endogenous CPSF30 to the NS1A protein, point to this NS1A binding site as a potential target for the development of antivirals directed against influenza A virus.

scholarly journals Differential Recognition of Influenza A Viruses by M158–66Epitope-Specific CD8+T Cells Is Determined by Extraepitopic Amino Acid Residues

2015 ◽  
Vol 90 (2) ◽  
pp. 1009-1022 ◽  
Author(s):  
Carolien E. van de Sandt ◽  
Joost H. C. M. Kreijtz ◽  
Martina M. Geelhoed-Mieras ◽  
Nella J. Nieuwkoop ◽  
Monique I. Spronken ◽  
...  
Keyword(s):  
Amino Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Rational Design ◽  
Amino Acid Residues ◽  
Virus Infections ◽  
Human Influenza ◽  
Influenza A Viruses ◽  
Specific Ctls ◽  
Naturally Occurring

ABSTRACTNatural influenza A virus infections elicit both virus-specific antibody and CD4+and CD8+T cell responses. Influenza A virus-specific CD8+cytotoxic T lymphocytes (CTLs) contribute to clearance of influenza virus infections. Viral CTL epitopes can display variation, allowing influenza A viruses to evade recognition by epitope-specific CTLs. Due to functional constraints, some epitopes, like the immunodominant HLA-A*0201-restricted matrix protein 1 (M158–66) epitope, are highly conserved between influenza A viruses regardless of their subtype or host species of origin. We hypothesized that human influenza A viruses evade recognition of this epitope by impairing antigen processing and presentation by extraepitopic amino acid substitutions. Activation of specific T cells was used as an indication of antigen presentation. Here, we show that the M158–66epitope in the M1 protein derived from human influenza A virus was poorly recognized compared to the M1 protein derived from avian influenza A virus. Furthermore, we demonstrate that naturally occurring variations at extraepitopic amino acid residues affect CD8+T cell recognition of the M158–66epitope. These data indicate that human influenza A viruses can impair recognition by M158–66-specific CTLs while retaining the conserved amino acid sequence of the epitope, which may represent a yet-unknown immune evasion strategy for influenza A viruses. This difference in recognition may have implications for the viral replication kinetics in HLA-A*0201 individuals and spread of influenza A viruses in the human population. The findings may aid the rational design of universal influenza vaccines that aim at the induction of cross-reactive virus-specific CTL responses.IMPORTANCEInfluenza viruses are an important cause of acute respiratory tract infections. Natural influenza A virus infections elicit both humoral and cellular immunity. CD8+cytotoxic T lymphocytes (CTLs) are directed predominantly against conserved internal proteins and confer cross-protection, even against influenza A viruses of various subtypes. In some CTL epitopes, mutations occur that allow influenza A viruses to evade recognition by CTLs. However, the immunodominant HLA-A*0201-restricted M158–66epitope does not tolerate mutations without loss of viral fitness. Here, we describe naturally occurring variations in amino acid residues outside the M158–66epitope that influence the recognition of the epitope. These results provide novel insights into the epidemiology of influenza A viruses and their pathogenicity and may aid rational design of vaccines that aim at the induction of CTL responses.

scholarly journals Grafting Methionine on 1F1 Ab Increases the Broad-Activity on HA Structural-Conserved Residues of H1, H2, and H3 Influenza a Viruses

2021 ◽  
Vol 17 ◽  
pp. 117693432110030
Author(s):  
Hoa Thanh Le ◽  
Phuc-Chau Do ◽  
Ly Le
Keyword(s):  
Amino Acid ◽  
Influenza A Virus ◽  
Broad Spectrum ◽  
Influenza A ◽  
Structural Alignment ◽  
Peptide Inhibitors ◽  
Influenza A Viruses ◽  
Conserved Residues ◽  
High Level ◽  
Cellular Fusion

A high level of mutation enables the influenza A virus to resist antibiotics previously effective against the influenza A virus. A portion of the structure of hemagglutinin HA is assumed to be well-conserved to maintain its role in cellular fusion, and the structure tends to be more conserved than sequence. We designed peptide inhibitors to target the conserved residues on the HA surface, which were identified based on structural alignment. Most of the conserved and strongly similar residues are located in the receptor-binding and esterase regions on the HA1 domain In a later step, fragments of anti-HA antibodies were gathered and screened for the binding ability to the found conserved residues. As a result, Methionine amino acid got the best docking score within the −2.8 Å radius of Van der Waals when it is interacting with Tyrosine, Arginine, and Glutamic acid. Then, the binding affinity and spectrum of the fragments were enhanced by grafting hotspot amino acid into the fragments to form peptide inhibitors. Our peptide inhibitor was able to form in silico contact with a structurally conserved region across H1, H2, and H3 HA, with the binding site at the boundary between HA1 and HA2 domains, spreading across different monomers, suggesting a new target for designing broad-spectrum antibody and vaccine. This research presents an affordable method to design broad-spectrum peptide inhibitors using fragments of an antibody as a scaffold.

scholarly journals Host Factor Rab11a is Critical for Efficient Assembly of Influenza A Virus Genomic Segments

2021 ◽  
Author(s):  
Julianna Han ◽  
Ketaki Ganti ◽  
Veeresh Kumar Sali ◽  
Carly Twigg ◽  
Yifeng Zhang ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Genome Assembly ◽  
Influenza A ◽  
Early Time ◽  
Virus Genome ◽  
Host Factor ◽  
Influenza A Viruses ◽  
Ribonucleoprotein Complexes ◽  
Microtubule Networks ◽  
Cellular Components

It is well documented that influenza A viruses selectively package 8 distinct viral ribonucleoprotein complexes (vRNPs) into each virion; however, the role of host factors in genome assembly is not completely understood. To evaluate the significance of cellular factors in genome assembly, we generated a reporter virus carrying a tetracysteine tag in the NP gene (NP-Tc virus) and assessed the dynamics of vRNP localization with cellular components by fluorescence microscopy. At early time points, vRNP complexes were preferentially exported to the MTOC; subsequently, vRNPs associated on vesicles positive for cellular factor Rab11a and formed distinct vRNP bundles that trafficked to the plasma membrane on microtubule networks. In Rab11a deficient cells, however, vRNP bundles were smaller in the cytoplasm with less co-localization between different vRNP segments. Furthermore, Rab11a deficiency increased the production of non-infectious particles with higher RNA copy number to PFU ratios, indicative of defects in specific genome assembly. These results indicate that Rab11a+ vesicles serve as hubs for the congregation of vRNP complexes and enable specific genome assembly through vRNP:vRNP interactions, revealing the importance of Rab11a as a critical host factor for influenza A virus genome assembly.

scholarly journals Specific Mutations in the PB2 Protein of Influenza A Virus Compensate for the Lack of Efficient Interferon Antagonism of the NS1 Protein of Bat Influenza A-Like Viruses

2018 ◽  
Vol 92 (7) ◽  
Author(s):  
Teresa Aydillo ◽  
Juan Ayllon ◽  
Amzie Pavlisin ◽  
Carles Martinez-Romero ◽  
Shashank Tripathi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Single Amino Acid ◽  
Type I ◽  
Ns1 Protein ◽  
Influenza A Viruses ◽  
Basic Biology

ABSTRACTRecently, two new influenza A-like viruses have been discovered in bats, A/little yellow-shouldered bat/Guatemala/060/2010 (HL17NL10) and A/flat-faced bat/Peru/033/2010 (HL18NL11). The hemagglutinin (HA)-like (HL) and neuraminidase (NA)-like (NL) proteins of these viruses lack hemagglutination and neuraminidase activities, despite their sequence and structural homologies with the HA and NA proteins of conventional influenza A viruses. We have now investigated whether the NS1 proteins of the HL17NL10 and HL18NL11 viruses can functionally replace the NS1 protein of a conventional influenza A virus. For this purpose, we generated recombinant influenza A/Puerto Rico/8/1934 (PR8) H1N1 viruses containing the NS1 protein of the PR8 wild-type, HL17NL10, and HL18NL11 viruses. These viruses (r/NS1PR8, r/NS1HL17, and r/NS1HL18, respectively) were tested for replication in bat and nonbat mammalian cells and in mice. Our results demonstrate that the r/NS1HL17 and r/NS1HL18 viruses are attenuatedin vitroandin vivo. However, the bat NS1 recombinant viruses showed a phenotype similar to that of the r/NS1PR8 virus in STAT1−/−human A549 cells and mice, bothin vitroandin vivosystems being unable to respond to interferon (IFN). Interestingly, multiple mouse passages of the r/NS1HL17 and r/NS1HL18 viruses resulted in selection of mutant viruses containing single amino acid mutations in the viral PB2 protein. In contrast to the parental viruses, virulence and IFN antagonism were restored in the selected PB2 mutants. Our results indicate that the NS1 protein of bat influenza A-like viruses is less efficient than the NS1 protein of its conventional influenza A virus NS1 counterpart in antagonizing the IFN response and that this deficiency can be overcome by the influenza virus PB2 protein.IMPORTANCESignificant gaps in our understanding of the basic features of the recently discovered bat influenza A-like viruses HL17NL10 and HL18NL11 remain. The basic biology of these unique viruses displays both similarities to and differences from the basic biology of conventional influenza A viruses. Here, we show that recombinant influenza A viruses containing the NS1 protein from HL17NL10 and HL18NL11 are attenuated. This attenuation was mediated by their inability to antagonize the type I IFN response. However, this deficiency could be compensated for by single amino acid replacements in the PB2 gene. Our results unravel a functional divergence between the NS1 proteins of bat influenza A-like and conventional influenza A viruses and demonstrate an interplay between the viral PB2 and NS1 proteins to antagonize IFN.

scholarly journals Avian ANP32B does not support influenza A virus polymerase and influenza A virus relies exclusively on ANP32A in chicken cells

2019 ◽  
Author(s):  
Jason S. Long ◽  
Alewo Idoko-Akoh ◽  
Bhakti Mistry ◽  
Daniel H. Goldhill ◽  
Ecco Staller ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Host Range ◽  
Influenza A Virus ◽  
Support Function ◽  
Influenza A ◽  
Polymerase Activity ◽  
Human Cells ◽  
Influenza A Viruses ◽  
The Poor

SummaryInfluenza A viruses (IAV) are subject to species barriers that prevent frequent zoonotic transmission and pandemics. One of these barriers is the poor activity of avian IAV polymerases in human cells. Differences between avian and mammalian ANP32 proteins underlie this host range barrier. Human ANP32A and ANP32B homologues both support function of human-adapted influenza polymerase but do not support efficient activity of avian IAV polymerase which requires avian ANP32A. We show here that avian ANP32B is evolutionarily distinct from mammalian ANP32B, and that chicken ANP32B does not support IAV polymerase activity even of human-adapted viruses. Consequently, IAV does not replicate in chicken cells that lack ANP32A. Amino acid differences in LRR5 domain accounted for the inactivity of chicken ANP32B. Transfer of these residues to chicken ANP32A abolished support of IAV polymerase. Understanding ANP32 function will help develop antiviral strategies and aid the design of influenza virus resistant genome edited chickens.

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