scholarly journals Characterization of changes in the hemagglutinin that accompanied the emergence of H3N2/1968 pandemic influenza viruses

2021 ◽  
Vol 17 (9) ◽  
pp. e1009566
Author(s):  
Johanna West ◽  
Juliane Röder ◽  
Tatyana Matrosovich ◽  
Jana Beicht ◽  
Jan Baumann ◽  
...  
Keyword(s):  
Pandemic Influenza ◽  
Conformational Stability ◽  
Influenza Viruses ◽  
Human Adaptation ◽  
Airway Epithelial ◽  
Receptor Specificity ◽  
Binding Profile ◽  
Epithelial Cultures ◽  
Binding Avidity

The hemagglutinin (HA) of A/H3N2 pandemic influenza viruses (IAVs) of 1968 differed from its inferred avian precursor by eight amino acid substitutions. To determine their phenotypic effects, we studied recombinant variants of A/Hong Kong/1/1968 virus containing either human-type or avian-type amino acids in the corresponding positions of HA. The precursor HA displayed receptor binding profile and high conformational stability typical for duck IAVs. Substitutions Q226L and G228S, in addition to their known effects on receptor specificity and replication, marginally decreased HA stability. Substitutions R62I, D63N, D81N and N193S reduced HA binding avidity. Substitutions R62I, D81N and A144G promoted viral replication in human airway epithelial cultures. Analysis of HA sequences revealed that substitutions D63N and D81N accompanied by the addition of N-glycans represent common markers of avian H3 HA adaptation to mammals. Our results advance understanding of genotypic and phenotypic changes in IAV HA required for avian-to-human adaptation and pandemic emergence.

scholarly journals Characterization of changes in the hemagglutinin that accompanied the emergence of H3N2/1968 pandemic influenza viruses

2021 ◽  
Author(s):  
Johanna West ◽  
Juliane Roeder ◽  
Tatyana Matrosovich ◽  
Jana Beicht ◽  
Jan Baumann ◽  
...  
Keyword(s):  
Pandemic Influenza ◽  
Conformational Stability ◽  
Influenza Viruses ◽  
Human Adaptation ◽  
Airway Epithelial ◽  
Receptor Specificity ◽  
Binding Profile ◽  
Epithelial Cultures ◽  
Binding Avidity

The hemagglutinin (HA) of A/H3N2 pandemic influenza viruses (IAVs) of 1968 differed from its inferred avian precursor by eight amino acid substitutions. To determine their phenotypic effects, we studied recombinant variants of A/Hong Kong/1/1968 virus containing either human-type or avian-type amino acids in the corresponding positions of HA. The precursor HA displayed receptor binding profile and high conformational stability typical for duck IAVs. Substitutions Q226L and G228S, in addition to their known effects on receptor specificity and replication, marginally decreased HA stability. Substitutions R62I, D63N, D81N and N193S reduced HA binding avidity. Substitutions R62I, D63N, D81N and A144G promoted virus replication in human airway epithelial cultures. Analysis of HA sequences revealed that substitutions D63N and D81N accompanied by the addition of N-glycans represent common markers of avian H3 HA adaptation to mammals. Our results advance understanding of genotypic and phenotypic changes in IAV HA required for avian-to-human adaptation and pandemic emergence.

scholarly journals Novel Polyanions Inhibiting Replication of Influenza Viruses

2016 ◽  
Vol 60 (4) ◽  
pp. 1955-1966 ◽  
Author(s):  
Justyna Ciejka ◽  
Aleksandra Milewska ◽  
Magdalena Wytrwal ◽  
Jacek Wojarski ◽  
Anna Golda ◽  
...  
Keyword(s):  
Influenza A ◽  
Ex Vivo ◽  
Virus Assembly ◽  
Influenza Viruses ◽  
Airway Epithelial ◽  
B Virus ◽  
Influenza Activity ◽  
Epithelial Cultures ◽  
Poorly Soluble

ABSTRACTNovel sulfonated derivatives of poly(allylamine hydrochloride) (NSPAHs) and N-sulfonated chitosan (NSCH) have been synthesized, and their activity against influenza A and B viruses has been studied and compared with that of a series of carrageenans, marine polysaccharides of well-documented anti-influenza activity. NSPAHs were found to be nontoxic and very soluble in water, in contrast to gel-forming and thus generally poorly soluble carrageenans.In vitroandex vivostudies using susceptible cells (Madin-Darby canine kidney epithelial cells and fully differentiated human airway epithelial cultures) demonstrated the antiviral effectiveness of NSPAHs. The activity of NSPAHs was proportional to the molecular mass of the chain and the degree of substitution of amino groups with sulfonate groups. Mechanistic studies showed that the NSPAHs and carrageenans inhibit influenza A and B virus assembly in the cell.

scholarly journals HA-Dependent Tropism of H5N1 and H7N9 Influenza Viruses to Human Endothelial Cells Is Determined by Reduced Stability of the HA, Which Allows the Virus To Cope with Inefficient Endosomal Acidification and Constitutively Expressed IFITM3

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
Luca Hensen ◽  
Tatyana Matrosovich ◽  
Katrin Roth ◽  
Hans-Dieter Klenk ◽  
Mikhail Matrosovich
Keyword(s):  
Endothelial Cells ◽  
Mdck Cells ◽  
Conformational Stability ◽  
Influenza Viruses ◽  
Viral Infectivity ◽  
Human Endothelial Cells ◽  
Receptor Specificity ◽  
Ph Optimum ◽  
Endosomal Acidification ◽  
Endosomal Ph

ABSTRACT Previous studies revealed that certain avian influenza A viruses (IAVs), including zoonotic H5N1 and H7N9 IAVs, infect cultured human lung microvascular endothelial cells (HULEC) more efficiently than other IAVs and that tropism to HULEC is determined by viral hemagglutinin (HA). To characterize mechanisms of HA-mediated endotheliotropism, we used 2:6 recombinant IAVs harboring HAs from distinctive avian and human viruses and found that efficient infection of HULEC correlated with low conformational stability of the HA. We next studied effects on viral infectivity of single-point amino acid substitutions in the HA of 2:6 recombinant virus A/Vietnam/1203/2004-PR8 (H5N1). Substitutions H8Q, H103Y, T315I, and K582I (K58I in the HA2 subunit), which increased stability of the HA, markedly reduced viral infectivity for HULEC, whereas substitutions K189N and K218Q, which altered typical H5N1 virus-like receptor specificity and reduced binding avidity of the HA, led to only marginal reduction of infectivity. None of these substitutions affected virus infection in MDCK cells. We confirmed the previous observation of elevated basal expression of IFITM3 protein in HULEC and found that endosomal acidification is less efficient in HULEC than in MDCK cells. In accord with these findings, counteraction of IFITM3-mediated restriction by amphotericin B and reduction of endosomal pH by moderate acidification of the extracellular medium enhanced infectivity of viruses with stable HA for HULEC without significant effect on infectivity for MDCK cells. Collectively, our results indicate that relatively high pH optimum of fusion of the HA of zoonotic H5N1 and H7N9 IAVs allows them to overcome antiviral effects of inefficient endosomal acidification and IFITM3 in human endothelial cells. IMPORTANCE Receptor specificity of the HA of IAVs is known to be a critical determinant of viral cell tropism. Here, we show that fusion properties of the HA may also play a key role in the tropism. Thus, we demonstrate that IAVs having a relatively low pH optimum of fusion cannot efficiently infect human endothelial cells owing to their relatively high endosomal pH and increased expression of fusion-inhibiting IFITM3 protein. These restrictions can be overcome by IAVs with elevated pH of fusion, such as zoonotic H5N1 and H7N9. Our results illustrate that the infectivity of IAVs depends on an interplay between HA conformational stability, endosomal acidification and IFITM3 expression in target cells, and the extracellular pH. Given significant variation of levels of HA stability among animal, human, and zoonotic IAVs, our findings prompt further studies on the fusion-dependent tropism of IAVs to different cell types in humans and its role in viral host range and pathogenicity.

scholarly journals Enhanced fitness of SARS-CoV-2 variant of concern B.1.1.7, but not B.1.351, in animal models

2021 ◽  
Author(s):  
Lorenz Ulrich ◽  
Nico Joel Halwe ◽  
Adriano Taddeo ◽  
Nadine Ebert ◽  
Jacob Sch&oumln ◽  
...  
Keyword(s):  
Multiple Models ◽  
Airway Epithelial ◽  
Upper Respiratory Tract ◽  
Hamster Model ◽  
Enhanced Transmission ◽  
Fitness Advantage ◽  
Epithelial Cultures ◽  
Upper Respiratory

Emerging variants of concern (VOCs) drive the SARS-CoV-2 pandemic. We assessed VOC B.1.1.7, now prevalent in several countries, and VOC B.1.351, representing the greatest threat to populations with immunity to the early SARS-CoV-2 progenitors. B.1.1.7 showed a clear fitness advantage over the progenitor variant (wt-S614G) in ferrets and two mouse models, where the substitutions in the spike glycoprotein were major drivers for fitness advantage. In the superspreader hamster model, B.1.1.7 and wt-S614G had comparable fitness, whereas B.1.351 was outcompeted. The VOCs had similar replication kinetics as compared to wt-S614G in human airway epithelial cultures. Our study highlights the importance of using multiple models for complete fitness characterization of VOCs and demonstrates adaptation of B.1.1.7 towards increased upper respiratory tract replication and enhanced transmission in vivo.

scholarly journals Adaptation of Pandemic H1N1 Influenza Viruses in Mice

2010 ◽  
Vol 84 (17) ◽  
pp. 8607-8616 ◽  
Author(s):  
Natalia A. Ilyushina ◽  
Alexey M. Khalenkov ◽  
Jon P. Seiler ◽  
Heather L. Forrest ◽  
Nicolai V. Bovin ◽  
...  
Keyword(s):  
Amino Acid ◽  
Pandemic Influenza ◽  
Influenza A ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Mouse Lung ◽  
Mammalian Host ◽  
Influenza A Viruses ◽  
Receptor Specificity ◽  
Viral Receptor

ABSTRACT The molecular mechanism by which pandemic 2009 influenza A viruses were able to sufficiently adapt to humans is largely unknown. Subsequent human infections with novel H1N1 influenza viruses prompted an investigation of the molecular determinants of the host range and pathogenicity of pandemic influenza viruses in mammals. To address this problem, we assessed the genetic basis for increased virulence of A/CA/04/09 (H1N1) and A/TN/1-560/09 (H1N1) isolates, which are not lethal for mice, in a new mammalian host by promoting their mouse adaptation. The resulting mouse lung-adapted variants showed significantly enhanced growth characteristics in eggs, extended extrapulmonary tissue tropism, and pathogenicity in mice. All mouse-adapted viruses except A/TN/1-560/09-MA2 grew faster and to higher titers in cells than the original strains. We found that 10 amino acid changes in the ribonucleoprotein (RNP) complex (PB2 E158G/A, PA L295P, NP D101G, and NP H289Y) and hemagglutinin (HA) glycoprotein (K119N, G155E, S183P, R221K, and D222G) controlled enhanced mouse virulence of pandemic isolates. HA mutations acquired during adaptation affected viral receptor specificity by enhancing binding to α2,3 together with decreasing binding to α2,6 sialyl receptors. PB2 E158G/A and PA L295P amino acid substitutions were responsible for the significant enhancement of transcription and replication activity of the mouse-adapted H1N1 variants. Taken together, our findings suggest that changes optimizing receptor specificity and interaction of viral polymerase components with host cellular factors are the major mechanisms that contribute to the optimal competitive advantage of pandemic influenza viruses in mice. These modulators of virulence, therefore, may have been the driving components of early evolution, which paved the way for novel 2009 viruses in mammals.

scholarly journals An evaluation of the InDevR FluChip-8G insight microarray assay in characterizing influenza a viruses

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Emily S. Bailey ◽  
Xinye Wang ◽  
Mai-juan Ma ◽  
Guo-lin Wang ◽  
Gregory C. Gray
Keyword(s):  
Influenza A ◽  
Influenza Viruses ◽  
Time Range ◽  
Influenza B ◽  
Influenza A Viruses ◽  
Laboratory Methods ◽  
Duke University ◽  
Multiple Viral Strains ◽  
Rapid Characterization

AbstractInfluenza viruses are an important cause of disease in both humans and animals, and their detection and characterization can take weeks. In this study, we sought to compare classical virology techniques with a new rapid microarray method for the detection and characterization of a very diverse, panel of animal, environmental, and human clinical or field specimens that were molecularly positive for influenza A alone (n = 111), influenza B alone (n = 3), both viruses (n = 13), or influenza negative (n = 2) viruses. All influenza virus positive samples in this study were first subtyped by traditional laboratory methods, and later evaluated using the FluChip-8G Insight Assay (InDevR Inc. Boulder, CO) in laboratories at Duke University (USA) or at Duke Kunshan University (China). The FluChip-8G Insight multiplexed assay agreed with classical virologic techniques 59 (54.1%) of 109 influenza A-positive, 3 (100%) of the 3 influenza B-positive, 0 (0%) of 10 both influenza A- and B-positive samples, 75% of 24 environmental samples including those positive for H1, H3, H7, H9, N1, and N9 strains, and 80% of 22 avian influenza samples. It had difficulty with avian N6 types and swine H3 and N2 influenza specimens. The FluChip-8G Insight assay performed well with most human, environmental, and animal samples, but had some difficulty with samples containing multiple viral strains and with specific animal influenza strains. As classical virology methods are often iterative and can take weeks, the FluChip-8G Insight Assay rapid results (time range 8 to 12 h) offers considerable time savings. As the FluChip-8G analysis algorithm is expected to improve over time with addition of new subtypes and sample matrices, the FluChip-8G Insight Assay has considerable promise for rapid characterization of novel influenza viruses affecting humans or animals.

scholarly journals Alpha-1 antitrypsin inhibits TMPRSS2 protease activity and SARS-CoV-2 infection

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lukas Wettstein ◽  
Tatjana Weil ◽  
Carina Conzelmann ◽  
Janis A. Müller ◽  
Rüdiger Groß ◽  
...  
Keyword(s):  
Serine Protease ◽  
Immune Defense ◽  
Innate Immune ◽  
Respiratory Pathogen ◽  
The Novel ◽  
Airway Epithelial ◽  
Protein Library ◽  
Epithelial Cultures ◽  
Alpha 1 Antitrypsin ◽  
Novel Coronavirus

AbstractSARS-CoV-2 is a respiratory pathogen and primarily infects the airway epithelium. As our knowledge about innate immune factors of the respiratory tract against SARS-CoV-2 is limited, we generated and screened a peptide/protein library derived from bronchoalveolar lavage for inhibitors of SARS-CoV-2 spike-driven entry. Analysis of antiviral fractions revealed the presence of α1-antitrypsin (α1AT), a highly abundant circulating serine protease inhibitor. Here, we report that α1AT inhibits SARS-CoV-2 entry at physiological concentrations and suppresses viral replication in cell lines and primary cells including human airway epithelial cultures. We further demonstrate that α1AT binds and inactivates the serine protease TMPRSS2, which enzymatically primes the SARS-CoV-2 spike protein for membrane fusion. Thus, the acute phase protein α1AT is an inhibitor of TMPRSS2 and SARS-CoV-2 entry, and may play an important role in the innate immune defense against the novel coronavirus. Our findings suggest that repurposing of α1AT-containing drugs has prospects for the therapy of COVID-19.

scholarly journals Seroprevalence of Pandemic Influenza Viruses, New York, New York, USA, 2004

2012 ◽  
Vol 18 (11) ◽  
pp. 1905-1907
Author(s):  
Isaac B. Weisfuse ◽  
Tshidi Tsibane ◽  
Kevin J. Konty ◽  
Joseph R. Egger ◽  
Elizabeth Needham Waddell ◽  
...  
Keyword(s):  
New York ◽  
Pandemic Influenza ◽  
Influenza Viruses

scholarly journals A comprehensive influenza reporter virus panel for high-throughput deep profiling of neutralizing antibodies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adrian Creanga ◽  
Rebecca A. Gillespie ◽  
Brian E. Fisher ◽  
Sarah F. Andrews ◽  
Julia Lederhofer ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Depth Profiling ◽  
Influenza Viruses ◽  
Effective Vaccine ◽  
Viral Gene ◽  
Broadly Neutralizing Antibodies ◽  
Level 2 ◽  
Biosafety Level ◽  
Major Target

AbstractBroadly neutralizing antibodies (bnAbs) have been developed as potential countermeasures for seasonal and pandemic influenza. Deep characterization of these bnAbs and polyclonal sera provides pivotal understanding for influenza immunity and informs effective vaccine design. However, conventional virus neutralization assays require high-containment laboratories and are difficult to standardize and roboticize. Here, we build a panel of engineered influenza viruses carrying a reporter gene to replace an essential viral gene, and develop an assay using the panel for in-depth profiling of neutralizing antibodies. Replication of these viruses is restricted to cells expressing the missing viral gene, allowing it to be manipulated in a biosafety level 2 environment. We generate the neutralization profile of 24 bnAbs using a 55-virus panel encompassing the near-complete diversity of human H1N1 and H3N2, as well as pandemic subtype viruses. Our system offers in-depth profiling of influenza immunity, including the antibodies against the hemagglutinin stem, a major target of universal influenza vaccines.

Sign in / Sign up

Export Citation Format

Share Document