scholarly journals CHANGE OF PHENOTYPIC PROPERTIES OF ESCAPE MUTANTS AND READAPTANTS OF INFLUENZA VIRUS A (H1N1) PDM09 UNDER THE INFLUENCE OF SELECTED MUTATIONS IN THE MOLECULE OF HEMAGGLUTININ

2019 ◽  
Vol 64 (2) ◽  
pp. 73-78
Author(s):  
T. A. Timofeeva ◽  
I. A. Rudneva ◽  
A. A. Shilov ◽  
M. A. Balanova ◽  
E. K. Artemov ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Comparative Study ◽  
Influenza A ◽  
Antigenic Specificity ◽  
Escape Mutant ◽  
Cellular Receptors ◽  
Influenza Virus A ◽  
Escape Mutants ◽  
Chicken Erythrocytes

Introduction. After the emergence and spread of pandemic H1N1 viruses in 2009, antigenic epitopes recognized by neutralizing antibodies against the hemagglutinin of influenza A/Moscow/01/09(H1N1)pdm09 viruses were studied. Targets and goals. The purpose of the study was to obtain readapted variants of the virus from a low-virulent escape-mutant that has an increased affinity of the avian and the human types cellular receptors compared to the wild type and the comparative study of their antigenic and receptor specificity. Material and methods. Viruses were accumulated in 10-day-old chicken embryos. The MAB panel against HA of influenza virus strain A/IIV-Moscow/01/09(H1N1)sw1 was used in the form of ascites fluids from mice. Immunization of mice, HI testing, elution of viruses from chicken erythrocytes, PCR and sequencing of readapted variants were performed by standard methods. Results. The amino acid substitution A198E acquired in the process of readaptation leads to changes in the antigenic specificity. A correlation was found between a decrease in virulence of a low-virulent escape mutant associated with the substitution D190N in the hemagglutinin molecule and an increase in the hemagglutinating titer to inhibitors in normal mouse serum. Viruses with low affinity of cellular receptor analogs and carrying amino acid substitutions have an increased ability to elute from chicken erythrocytes. Discussion. The results discuss the effect of mutations in the HA molecule of the influenza A(H1N1)pdm09 virus to the change in antigen specificity; virulence for mice, adsorption-elution at cellular receptors. Conclusion. A comparative study of the antigenic specificity and receptor-binding activity of the escape mutants was conducted for the hemagglutinin of the influenza virus A/Moscow/01/2009 (H1N1)swl, and the readapted variants obtained for one of the escape mutants with reduced virulence for mouse. Monitoring the pleiotropic effect of mutations in the hemagglutinin H1 molecule is necessary to predict variants of the virus with pandemic potential.

scholarly journals Antibody Epitopes on the Neuraminidase of a Recent H3N2 Influenza Virus (A/Memphis/31/98)

2002 ◽  
Vol 76 (23) ◽  
pp. 12274-12280 ◽  
Author(s):  
Upma Gulati ◽  
Chi-Ching Hwang ◽  
Lalitha Venkatramani ◽  
Shelly Gulati ◽  
Stephen J. Stray ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Monoclonal Antibodies ◽  
Amino Acid ◽  
Binding Pocket ◽  
Wild Type Virus ◽  
Escape Mutation ◽  
Wild Type ◽  
Influenza Virus A ◽  
Directed Mutation ◽  
Escape Mutants

ABSTRACT We have characterized monoclonal antibodies raised against the neuraminidase (NA) of a Sydney-like influenza virus (A/Memphis/31/98, H3N2) in a reassortant virus A/NWS/33HA-A/Mem/31/98NA (H1N2) and nine escape mutants selected by these monoclonal antibodies. Five of the antibodies use the same heavy chain VDJ genes and may not be independent. Another antibody, Mem5, uses the same VH and J genes with a different D gene and different isotype. Sequence changes in escape mutants selected by these antibodies occur in two loops of the NA, at amino acid 198, 199, 220, or 221. These amino acids are located on the opposite side of the NA monomer to the major epitopes found in N9 and early N2 NAs. Escape mutants with a change at 198 have reduced NA activity compared to the wild-type virus. Asp198 points toward the substrate binding pocket, and we had previously found that a site-directed mutation of this amino acid resulted in a loss of enzyme activity (M. R. Lentz, R. G. Webster, and G. M. Air, Biochemistry 26:5351-5358, 1987). Mutations at residue 199, 220, or 221 did not alter the NA activity significantly compared to that of wild-type NA. A 3.5-Å structure of Mem5 Fab complexed with the Mem/98 NA shows that the Mem5 antibody binds at the sites of escape mutation selected by the other antibodies.

scholarly journals S-Acylation of Proteins of Coronavirus and Influenza Virus: Conservation of Acylation Sites in Animal Viruses and DHHC Acyltransferases in Their Animal Reservoirs

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 669
Author(s):  
Dina A. Abdulrahman ◽  
Xiaorong Meng ◽  
Michael Veit
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Ion Channels ◽  
Substrate Specificity ◽  
Influenza A ◽  
3D Structure ◽  
Viral Fitness ◽  
Amino Acid Substitutions ◽  
Essential Function ◽  
Animal Reservoirs

Recent pandemics of zoonotic origin were caused by members of coronavirus (CoV) and influenza A (Flu A) viruses. Their glycoproteins (S in CoV, HA in Flu A) and ion channels (E in CoV, M2 in Flu A) are S-acylated. We show that viruses of all genera and from all hosts contain clusters of acylated cysteines in HA, S and E, consistent with the essential function of the modification. In contrast, some Flu viruses lost the acylated cysteine in M2 during evolution, suggesting that it does not affect viral fitness. Members of the DHHC family catalyze palmitoylation. Twenty-three DHHCs exist in humans, but the number varies between vertebrates. SARS-CoV-2 and Flu A proteins are acylated by an overlapping set of DHHCs in human cells. We show that these DHHC genes also exist in other virus hosts. Localization of amino acid substitutions in the 3D structure of DHHCs provided no evidence that their activity or substrate specificity is disturbed. We speculate that newly emerged CoVs or Flu viruses also depend on S-acylation for replication and will use the human DHHCs for that purpose. This feature makes these DHHCs attractive targets for pan-antiviral drugs.

scholarly journals Characterization of an enhanced antigenic change in the pandemic 2009 H1N1 influenza virus haemagglutinin

2014 ◽  
Vol 95 (5) ◽  
pp. 1033-1042 ◽  
Author(s):  
Blanca García-Barreno ◽  
Teresa Delgado ◽  
Sonia Benito ◽  
Inmaculada Casas ◽  
Francisco Pozo ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Influenza A ◽  
Point Mutations ◽  
Antigenic Site ◽  
Single Amino Acid ◽  
Antigenic Structure ◽  
Human Antibody ◽  
2009 H1n1

Murine hybridomas producing neutralizing mAbs specific to the pandemic influenza virus A/California/07/2009 haemagglutinin (HA) were isolated. These antibodies recognized at least two different but overlapping new epitopes that were conserved in the HA of most Spanish pandemic isolates. However, one of these isolates (A/Extremadura/RR6530/2010) lacked reactivity with the mAbs and carried two unique mutations in the HA head (S88Y and K136N) that were required simultaneously to eliminate reactivity with the murine antibodies. This unusual requirement directly illustrates the phenomenon of enhanced antigenic change proposed previously for the accumulation of simultaneous amino acid substitutions at antigenic sites of the influenza A virus HA during virus evolution (Shih et al., Proc Natl Acad Sci USA, 104 , 6283–6288, 2007). The changes found in the A/Extremadura/RR6530/2010 HA were not found in escape mutants selected in vitro with one of the mAbs, which contained instead nearby single amino acid changes in the HA head. Thus, either single or double point mutations may similarly alter epitopes of the new antigenic site identified in this work in the 2009 H1N1 pandemic virus HA. Moreover, this site is relevant for the human antibody response, as shown by competition of mAbs and human post-infection sera for virus binding. The results are discussed in the context of the HA antigenic structure and challenges posed for identification of sequence changes with possible antigenic impact during virus surveillance.

Escape mutants of pandemic influenza A/H1N1 2009 virus: Variations in antigenic specificity and receptor affinity of the hemagglutinin

2012 ◽  
Vol 166 (1-2) ◽  
pp. 61-67 ◽  
Author(s):  
Irina Rudneva ◽  
Anna Ignatieva ◽  
Tatiana Timofeeva ◽  
Aleksandr Shilov ◽  
Alla Kushch ◽  
...  
Keyword(s):  
Pandemic Influenza ◽  
Influenza A ◽  
Antigenic Specificity ◽  
Receptor Affinity ◽  
Influenza A H1n1 ◽  
Escape Mutants

scholarly journals Characterization of H9N2 influenza A viruses isolated from chicken products imported into Japan from China

2006 ◽  
Vol 135 (3) ◽  
pp. 386-391 ◽  
Author(s):  
M. MASE ◽  
M. ETO ◽  
K. IMAI ◽  
K. TSUKAMOTO ◽  
S. YAMAGUCHI
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Influenza A ◽  
H9n2 Virus ◽  
Amino Acid Substitutions ◽  
Influenza A Viruses ◽  
Potential Sources

We characterized eleven H9N2 influenza A viruses isolated from chicken products imported from China. Genetically they were classified into six distinct genotypes, including five already known genotypes and one novel genotype. This suggested that such multiple genotypes of the H9N2 virus have possibly already become widespread and endemic in China. Two isolates have amino-acid substitutions that confer resistance to amantadine in the M2 region, and this supported the evidence that this mutation might be a result of the wide application of amantadine for avian influenza treatment in China. These findings emphasize the importance of surveillance for avian influenza virus in this region, and of quarantining imported chicken products as potential sources for the introduction of influenza virus.

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 Plasticity of the Influenza Virus H5 HA Protein

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Huihui Kong ◽  
David F. Burke ◽  
Tiago Jose da Silva Lopes ◽  
Kosuke Takada ◽  
Masaki Imai ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Mammalian Cells ◽  
Influenza A ◽  
Viral Antigen ◽  
Influenza Viruses ◽  
Influenza A Viruses ◽  
Highly Pathogenic ◽  
Antigenic Properties ◽  
Ha Protein

ABSTRACT Since the emergence of highly pathogenic avian influenza viruses of the H5 subtype, the major viral antigen, hemagglutinin (HA), has undergone constant evolution, resulting in numerous genetic and antigenic (sub)clades. To explore the consequences of amino acid changes at sites that may affect the antigenicity of H5 viruses, we simultaneously mutated 17 amino acid positions of an H5 HA by using a synthetic gene library that, theoretically, encodes all combinations of the 20 amino acids at the 17 positions. All 251 mutant viruses sequenced possessed ≥13 amino acid substitutions in HA, demonstrating that the targeted sites can accommodate a substantial number of mutations. Selection with ferret sera raised against H5 viruses of different clades resulted in the isolation of 39 genotypes. Further analysis of seven variants demonstrated that they were antigenically different from the parental virus and replicated efficiently in mammalian cells. Our data demonstrate the substantial plasticity of the influenza virus H5 HA protein, which may lead to novel antigenic variants. IMPORTANCE The HA protein of influenza A viruses is the major viral antigen. In this study, we simultaneously introduced mutations at 17 amino acid positions of an H5 HA expected to affect antigenicity. Viruses with ≥13 amino acid changes in HA were viable, and some had altered antigenic properties. H5 HA can therefore accommodate many mutations in regions that affect antigenicity. The substantial plasticity of H5 HA may facilitate the emergence of novel antigenic variants.

scholarly journals The model of prediction of the inhibition of neuraminidases of influenza A and B based on a reduced set of energy terms

2019 ◽  
Vol 65 (6) ◽  
pp. 520-525 ◽  
Author(s):  
A.V. Mikurova ◽  
V.S. Skvortsov
Keyword(s):  
Influenza Virus ◽  
Potential Energy ◽  
Correlation Coefficient ◽  
Influenza A ◽  
Protein Complexes ◽  
Computation Time ◽  
Inhibitor Protein ◽  
Data Set ◽  
Influenza Virus A ◽  
Calculation Procedures

The overall model for prediction of IC₅₀ values for inhibitors of neuraminidase influenza virus A and B has been created. It combines data about IC₅₀ values of complexes of 40 variants of neuraminidases of influenza A (7 serotypes) and B and three known inhibitors (oseltamivir, zanamivir, peramivir). The model also uses only data of enthalpy contributions to the potential energy of inhibitor/protein and substrate (MUNANA)/protein complexes. The calculation procedures are ported to use software with support of GPU accelerators, that significant decrease the computation time. The corresponding correlation coefficient (R²) for pIC₅₀ prediction was within 0.45-0.58, the SEM values of around 0.7 (the range of used pIC₅₀ data set is from 4.55 to 10.22).

scholarly journals Molecular Characterization of a Novel Avian Influenza A (H2N9) Strain Isolated from Wild Duck in Korea in 2018

Viruses ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1046 ◽  
Author(s):  
Seon-Ju Yeo ◽  
Duc-Duong Than ◽  
Hong-Seog Park ◽  
Haan Woo Sung ◽  
Hyun Park
Keyword(s):  
Influenza Virus ◽  
Amino Acid ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
Influenza A ◽  
Matrix Protein ◽  
Sequence Similarity ◽  
Wild Birds ◽  
Structural Protein ◽  
Wild Duck

A novel avian influenza virus (A/wild duck/Korea/K102/2018) (H2N9) was isolated from wild birds in South Korea in 2018, and phylogenetic and molecular analyses were conducted on complete gene sequences obtained by next-generation sequencing. Phylogenetic analysis indicated that the hemagglutinin (HA) and neuraminidase (NA) genes of the A/wild duck/Korea/K102/2018 (H2N9) virus belonged to the Eurasian countries, whereas other internal genes (polymerase basic protein 1 (PB1), PB2, nucleoprotein (NP), polymerase acidic protein (PA), matrix protein (M), and non-structural protein (NS)) belonged to the East Asian countries. A monobasic amino acid (PQIEPR/GLF) at the HA cleavage site, E627 in the PB2 gene, and no deletion of the stalk region in the NA gene indicated that the A/wild duck/Korea/K102/2018 (H2N9) isolate was a typical low pathogenicity avian influenza (LPAI). Nucleotide sequence similarity analysis of HA revealed that the highest homology (98.34%) is to that of A/duck/Mongolia/482/2015 (H2N3), and amino acid sequence of NA was closely related to that of A/duck/Bangladesh/8987/2010 (H10N9) (96.45%). In contrast, internal genes showed homology higher than 98% compared to those of other isolates derived from duck and wild birds of China or Japan in 2016–2018. The newly isolated A/wild duck/Korea/K102/2018 (H2N9) strain is the first reported avian influenza virus in Korea, and may have evolved from multiple genotypes in wild birds and ducks in Mongolia, China, and Japan.

Sign in / Sign up

Export Citation Format

Share Document