scholarly journals Key amino acid residues of neuraminidase involved in influenza A virus entry

2019 ◽  
Vol 77 (6) ◽  
Author(s):  
Fangzhao Chen ◽  
Teng Liu ◽  
Jiagui Xu ◽  
Yingna Huang ◽  
Shuwen Liu ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Influenza A Virus ◽  
Viral Entry ◽  
Influenza A ◽  
Mutational Analysis ◽  
Critical Role ◽  
Target Cells ◽  
Amino Acid Residues ◽  
Influenza Virus Neuraminidase

ABSTRACT Generally, influenza virus neuraminidase (NA) plays a critical role in the release stage of influenza virus. Recently, it has been found that NA may promote influenza virus to access the target cells. However, the mechanism remain unclear. Here, we reported that peramivir indeed possessed anti-influenza A virus (IAV) activity in the stage of viral entry. Importantly, we verified the critical residues of influenza NA involved in the viral entry. As a result, peramivir as an efficient NA inhibitor could suppress the initiation of IAV infection. Furthermore, mutational analysis showed NA might be associated with viral entry via amino acids residues R118, E119, D151, R152, W178, I222, E227, E276, R292 and R371. Our results demonstrated NA must contain the key amino acid residues can involve in IAV entry.

scholarly journals Influenza A Virus Hemagglutinin and Other Pathogen Glycoprotein Interactions with NK Cell Natural Cytotoxicity Receptors NKp46, NKp44, and NKp30

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 156
Author(s):  
Jasmina M. Luczo ◽  
Sydney L. Ronzulli ◽  
Stephen M. Tompkins
Keyword(s):  
Influenza Virus ◽  
Nk Cells ◽  
Influenza A Virus ◽  
Influenza A ◽  
Nk Cell ◽  
Influenza Virus Infection ◽  
Target Cells ◽  
Natural Cytotoxicity ◽  
Activating Receptors ◽  
Natural Cytotoxicity Receptors

Natural killer (NK) cells are part of the innate immunity repertoire, and function in the recognition and destruction of tumorigenic and pathogen-infected cells. Engagement of NK cell activating receptors can lead to functional activation of NK cells, resulting in lysis of target cells. NK cell activating receptors specific for non-major histocompatibility complex ligands are NKp46, NKp44, NKp30, NKG2D, and CD16 (also known as FcγRIII). The natural cytotoxicity receptors (NCRs), NKp46, NKp44, and NKp30, have been implicated in functional activation of NK cells following influenza virus infection via binding with influenza virus hemagglutinin (HA). In this review we describe NK cell and influenza A virus biology, and the interactions of influenza A virus HA and other pathogen lectins with NK cell natural cytotoxicity receptors (NCRs). We review concepts which intersect viral immunology, traditional virology and glycobiology to provide insights into the interactions between influenza virus HA and the NCRs. Furthermore, we provide expert opinion on future directions that would provide insights into currently unanswered questions.

scholarly journals Functional Analysis of PA Binding by Influenza A Virus PB1: Effects on Polymerase Activity and Viral Infectivity

2001 ◽  
Vol 75 (17) ◽  
pp. 8127-8136 ◽  
Author(s):  
Daniel R. Perez ◽  
Ruben O. Donis
Keyword(s):  
Amino Acids ◽  
Influenza Virus ◽  
Amino Acid ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Influenza A ◽  
Amino Acid Sequences ◽  
Influenza Viruses ◽  
Virus Growth ◽  
Transcription And Replication

ABSTRACT Influenza A virus expresses three viral polymerase (P) subunits—PB1, PB2, and PA—all of which are essential for RNA and viral replication. The functions of P proteins in transcription and replication have been partially elucidated, yet some of these functions seem to be dependent on the formation of a heterotrimer for optimal viral RNA transcription and replication. Although it is conceivable that heterotrimer subunit interactions may allow a more efficient catalysis, direct evidence of their essentiality for viral replication is lacking. Biochemical studies addressing the molecular anatomy of the P complexes have revealed direct interactions between PB1 and PB2 as well as between PB1 and PA. Previous studies have shown that the N-terminal 48 amino acids of PB1, termed domain α, contain the residues required for binding PA. We report here the refined mapping of the amino acid sequences within this small region of PB1 that are indispensable for binding PA by deletion mutagenesis of PB1 in a two-hybrid assay. Subsequently, we used site-directed mutagenesis to identify the critical amino acid residues of PB1 for interaction with PA in vivo. The first 12 amino acids of PB1 were found to constitute the core of the interaction interface, thus narrowing the previous boundaries of domain α. The role of the minimal PB1 domain α in influenza virus gene expression and genome replication was subsequently analyzed by evaluating the activity of a set of PB1 mutants in a model reporter minigenome system. A strong correlation was observed between a functional PA binding site on PB1 and P activity. Influenza viruses bearing mutant PB1 genes were recovered using a plasmid-based influenza virus reverse genetics system. Interestingly, mutations that rendered PB1 unable to bind PA were either nonviable or severely growth impaired. These data are consistent with an essential role for the N terminus of PB1 in binding PA, P activity, and virus growth.

scholarly journals Epitope specificity plays a critical role in regulating antibody-dependent cell-mediated cytotoxicity against influenza A virus

2016 ◽  
Vol 113 (42) ◽  
pp. 11931-11936 ◽  
Author(s):  
Wenqian He ◽  
Gene S. Tan ◽  
Caitlin E. Mullarkey ◽  
Amanda J. Lee ◽  
Mannie Man Wai Lam ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Neutralizing Antibodies ◽  
Influenza A ◽  
Critical Role ◽  
Host Cells ◽  
Viral Glycoprotein ◽  
Effector Functions ◽  
Dependent Cell

The generation of strain-specific neutralizing antibodies against influenza A virus is known to confer potent protection against homologous infections. The majority of these antibodies bind to the hemagglutinin (HA) head domain and function by blocking the receptor binding site, preventing infection of host cells. Recently, elicitation of broadly neutralizing antibodies which target the conserved HA stalk domain has become a promising “universal” influenza virus vaccine strategy. The ability of these antibodies to elicit Fc-dependent effector functions has emerged as an important mechanism through which protection is achieved in vivo. However, the way in which Fc-dependent effector functions are regulated by polyclonal influenza virus-binding antibody mixtures in vivo has never been defined. Here, we demonstrate that interactions among viral glycoprotein-binding antibodies of varying specificities regulate the magnitude of antibody-dependent cell-mediated cytotoxicity induction. We show that the mechanism responsible for this phenotype relies upon competition for binding to HA on the surface of infected cells and virus particles. Nonneutralizing antibodies were poor inducers and did not inhibit antibody-dependent cell-mediated cytotoxicity. Interestingly, anti-neuraminidase antibodies weakly induced antibody-dependent cell-mediated cytotoxicity and enhanced induction in the presence of HA stalk-binding antibodies in an additive manner. Our data demonstrate that antibody specificity plays an important role in the regulation of ADCC, and that cross-talk among antibodies of varying specificities determines the magnitude of Fc receptor-mediated effector functions.

scholarly journals Location of antigenic sites recognized by monoclonal antibodies in the influenza A virus nucleoprotein molecule

2009 ◽  
Vol 90 (7) ◽  
pp. 1730-1733 ◽  
Author(s):  
Natalia L. Varich ◽  
Konstantin S. Kochergin-Nikitsky ◽  
Evgeny V. Usachev ◽  
Olga V. Usacheva ◽  
Alexei G. Prilipov ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Amino Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Antigenic Variation ◽  
Strain Differences ◽  
Antigenic Structure ◽  
Amino Acid Residues ◽  
Mutant Proteins ◽  
Antigenic Sites

The locations of amino acid positions relevant to antigenic variation in the nucleoprotein (NP) of influenza virus are not conclusively known. We analysed the antigenic structure of influenza A virus NP by introducing site-specific mutations at amino acid positions presumed to be relevant for the differentiation of strain differences by anti-NP monoclonal antibodies. Mutant proteins were expressed in a prokaryotic system and analysed by performing ELISA with monoclonal antibodies. Four amino acid residues were found to determine four different antibody-binding sites. When mapped in a 3D X-ray model of NP, the four antigenically relevant amino acid positions were found to be located in separate physical sites of the NP molecule.

scholarly journals Deep Mutational Scan of the Highly Conserved Influenza A Virus M1 Matrix Protein Reveals Substantial Intrinsic Mutational Tolerance

2019 ◽  
Vol 93 (13) ◽  
Author(s):  
Nancy Hom ◽  
Lauren Gentles ◽  
Jesse D. Bloom ◽  
Kelly K. Lee
Keyword(s):  
Cell Culture ◽  
Influenza Virus ◽  
Amino Acid ◽  
Viral Replication ◽  
Influenza A Virus ◽  
Influenza A ◽  
Matrix Protein ◽  
Influenza Virus Infection ◽  
Sequence Diversity ◽  
Virus Protein

ABSTRACTInfluenza A virus matrix protein M1 is involved in multiple stages of the viral infectious cycle. Despite its functional importance, our present understanding of this essential viral protein is limited. The roles of a small subset of specific amino acids have been reported, but a more comprehensive understanding of the relationship between M1 sequence, structure, and virus fitness remains elusive. In this study, we used deep mutational scanning to measure the effect of every amino acid substitution in M1 on viral replication in cell culture. The map of amino acid mutational tolerance we have generated allows us to identify sites that are functionally constrained in cell culture as well as sites that are less constrained. Several sites that exhibit low tolerance to mutation have been found to be critical for M1 function and production of viable virions. Surprisingly, significant portions of the M1 sequence, especially in the C-terminal domain, whose structure is undetermined, were found to be highly tolerant of amino acid variation, despite having extremely low levels of sequence diversity among natural influenza virus strains. This unexpected discrepancy indicates that not all sites in M1 that exhibit high sequence conservation in nature are under strong constraint during selection for viral replication in cell culture.IMPORTANCEThe M1 matrix protein is critical for many stages of the influenza virus infection cycle. Currently, we have an incomplete understanding of this highly conserved protein’s function and structure. Key regions of M1, particularly in the C terminus of the protein, remain poorly characterized. In this study, we used deep mutational scanning to determine the extent of M1’s tolerance to mutation. Surprisingly, nearly two-thirds of the M1 sequence exhibits a high tolerance for substitutions, contrary to the extremely low sequence diversity observed across naturally occurring M1 isolates. Sites with low mutational tolerance were also identified, suggesting that they likely play critical functional roles and are under selective pressure. These results reveal the intrinsic mutational tolerance throughout M1 and shape future inquiries probing the functions of this essential influenza A virus protein.

scholarly journals RNA-Sequencing-Based Transcriptomic Analysis Reveals a Role for Annexin-A1 in Classical and Influenza A Virus-Induced Autophagy

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1399 ◽  
Author(s):  
Jianzhou Cui ◽  
Dhakshayini Morgan ◽  
Dao Han Cheng ◽  
Sok Lin Foo ◽  
Gracemary L. R. Yap ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Influenza A ◽  
Influenza Infection ◽  
Critical Role ◽  
Mtor Inhibitors ◽  
Influenza Viruses ◽  
Annexin A1 ◽  
Underlying Mechanisms

Influenza viruses have been shown to use autophagy for their survival. However, the proteins and mechanisms involved in the autophagic process triggered by the influenza virus are unclear. Annexin-A1 (ANXA1) is an immunomodulatory protein involved in the regulation of the immune response and Influenza A virus (IAV) replication. In this study, using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 (CRISPR associated protein 9) deletion of ANXA1, combined with the next-generation sequencing, we systematically analyzed the critical role of ANXA1 in IAV infection as well as the detailed processes governing IAV infection, such as macroautophagy. A number of differentially expressed genes were uniquely expressed in influenza A virus-infected A549 parental cells and A549 ∆ANXA1 cells, which were enriched in the immune system and infection-related pathways. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed the role of ANXA1 in autophagy. To validate this, the effect of mechanistic target of rapamycin (mTOR) inhibitors, starvation and influenza infection on autophagy was determined, and our results demonstrate that ANXA1 enhances autophagy induced by conventional autophagy inducers and influenza virus. These results will help us to understand the underlying mechanisms of IAV infection and provide a potential therapeutic target for restricting influenza viral replication and infection.

scholarly journals Amino Acid Residues 68–71 Contribute to Influenza A Virus PB1-F2 Protein Stability and Functions

2017 ◽  
Vol 8 ◽  
Author(s):  
Yi-Ying Cheng ◽  
Shih-Rang Yang ◽  
Ying-Ting Wang ◽  
Yu-Hsin Lin ◽  
Chi-Ju Chen
Keyword(s):  
Amino Acid ◽  
Protein Stability ◽  
Influenza A Virus ◽  
Influenza A ◽  
Amino Acid Residues

scholarly journals Assessment of Seasonal Influenza A Virus-Specific CD4 T-Cell Responses to 2009 Pandemic H1N1 Swine-Origin Influenza A Virus

2010 ◽  
Vol 84 (7) ◽  
pp. 3312-3319 ◽  
Author(s):  
Xinhui Ge ◽  
Venus Tan ◽  
Paul L. Bollyky ◽  
Nathan E. Standifer ◽  
Eddie A. James ◽  
...  
Keyword(s):  
T Cells ◽  
Influenza Virus ◽  
Amino Acid ◽  
T Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Seasonal Influenza ◽  
T Cell Responses ◽  
Pandemic H1n1 ◽  
Cell Responses

ABSTRACT Very limited evidence has been reported to show human adaptive immune responses to the 2009 pandemic H1N1 swine-origin influenza A virus (S-OIV). We studied 17 S-OIV peptides homologous to immunodominant CD4 T epitopes from hemagglutinin (HA), neuraminidase (NA), nuclear protein (NP), M1 matrix protein (MP), and PB1 of a seasonal H1N1 strain. We concluded that 15 of these 17 S-OIV peptides would induce responses of seasonal influenza virus-specific T cells. Of these, seven S-OIV sequences were identical to seasonal influenza virus sequences, while eight had at least one amino acid that was not conserved. T cells recognizing epitopes derived from these S-OIV antigens could be detected ex vivo. Most of these T cells expressed memory markers, although none of the donors had been exposed to S-OIV. Functional analysis revealed that specific amino acid differences in the sequences of these S-OIV peptides would not affect or partially affect memory T-cell responses. These findings suggest that without protective antibody responses, individuals vaccinated against seasonal influenza A may still benefit from preexisting cross-reactive memory CD4 T cells reducing their susceptibility to S-OIV infection.

scholarly journals Amino Acid Residues in the Fusion Peptide Pocket Regulate the pH of Activation of the H5N1 Influenza Virus Hemagglutinin Protein

2009 ◽  
Vol 83 (8) ◽  
pp. 3568-3580 ◽  
Author(s):  
Mark L. Reed ◽  
Hui-Ling Yen ◽  
Rebecca M. DuBois ◽  
Olga A. Bridges ◽  
Rachelle Salomon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Influenza A Virus ◽  
Influenza A ◽  
Coiled Coil ◽  
Fusion Peptide ◽  
Influenza Viruses ◽  
Amino Acid Residues ◽  
H5n1 Influenza ◽  
Coiled Coil Domain ◽  
Ha Protein

ABSTRACT The receptor specificity and cleavability of the hemagglutinin (HA) protein have been shown to regulate influenza A virus transmissibility and pathogenicity, but little is known about how its pH of activation contributes to these important biological properties. To identify amino acid residues that regulate the acid stability of the HA protein of H5N1 influenza viruses, we performed a mutational analysis of the HA protein of the moderately pathogenic A/chicken/Vietnam/C58/04 (H5N1) virus. Nineteen HA proteins containing point mutations in the HA2 coiled-coil domain or in an HA1 histidine or basic patch were generated. Wild-type and mutant HA plasmids were transiently transfected in cell culture and analyzed for total protein expression, surface expression, cleavage efficiency, pH of fusion, and pH of conformational change. Four mutations to residues in the fusion peptide pocket, Y23H and H24Q in the HA1 subunit and E105K and N114K in the HA2 subunit, and a K58I mutation in the HA2 coiled-coil domain significantly altered the pH of activation of the H5 HA protein. In some cases, the magnitude and direction of changes of individual mutations in the H5 HA protein differed considerably from similar mutations in other influenza A virus HA subtypes. Introduction of Y23H, H24Q, K58I, and N114K mutations into recombinant viruses resulted in virus-expressed HA proteins with similar shifts in the pH of fusion. Overall, the data show that residues comprising the fusion peptide pocket are important in triggering pH-dependent activation of the H5 HA protein.

Sign in / Sign up

Export Citation Format

Share Document