TMPRSS2 Is the Major Activating Protease of Influenza A Virus in Primary Human Airway Cells and Influenza B Virus in Human Type II Pneumocytes

ABSTRACT Cleavage of influenza virus hemagglutinin (HA) by host cell proteases is essential for virus infectivity and spread. We previously demonstrated in vitro that the transmembrane protease TMPRSS2 cleaves influenza A virus (IAV) and influenza B virus (IBV) HA possessing a monobasic cleavage site. Subsequent studies revealed that TMPRSS2 is crucial for the activation and pathogenesis of H1N1pdm and H7N9 IAV in mice. In contrast, activation of H3N2 IAV and IBV was found to be independent of TMPRSS2 expression and supported by an as-yet-undetermined protease(s). Here, we investigated the role of TMPRSS2 in proteolytic activation of IAV and IBV in three human airway cell culture systems: primary human bronchial epithelial cells (HBEC), primary type II alveolar epithelial cells (AECII), and Calu-3 cells. Knockdown of TMPRSS2 expression was performed using a previously described antisense peptide-conjugated phosphorodiamidate morpholino oligomer, T-ex5, that interferes with splicing of TMPRSS2 pre-mRNA, resulting in the expression of enzymatically inactive TMPRSS2. T-ex5 treatment produced efficient knockdown of active TMPRSS2 in all three airway cell culture models and prevented proteolytic activation and multiplication of H7N9 IAV in Calu-3 cells and H1N1pdm, H7N9, and H3N2 IAV in HBEC and AECII. T-ex5 treatment also inhibited the activation and spread of IBV in AECII but did not affect IBV activation in HBEC and Calu-3 cells. This study identifies TMPRSS2 as the major HA-activating protease of IAV in human airway cells and IBV in type II pneumocytes and as a potential target for the development of novel drugs to treat influenza infections. IMPORTANCE Influenza A viruses (IAV) and influenza B viruses (IBV) cause significant morbidity and mortality during seasonal outbreaks. Cleavage of the viral surface glycoprotein hemagglutinin (HA) by host proteases is a prerequisite for membrane fusion and essential for virus infectivity. Inhibition of relevant proteases provides a promising therapeutic approach that may avoid the development of drug resistance. HA of most influenza viruses is cleaved at a monobasic cleavage site, and a number of proteases have been shown to cleave HA in vitro. This study demonstrates that the transmembrane protease TMPRSS2 is the major HA-activating protease of IAV in primary human bronchial cells and of both IAV and IBV in primary human type II pneumocytes. It further reveals that human and murine airway cells can differ in their HA-cleaving protease repertoires. Our data will help drive the development of potent and selective protease inhibitors as novel drugs for influenza treatment.

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A Reverse Genetics Approach for Recovery of Recombinant Influenza B Viruses Entirely from cDNA

Journal of Virology ◽

10.1128/jvi.76.22.11744-11747.2002 ◽

2002 ◽

Vol 76 (22) ◽

pp. 11744-11747 ◽

Cited By ~ 53

Author(s):

David Jackson ◽

Andrew Cadman ◽

Thomas Zurcher ◽

Wendy S. Barclay

Keyword(s):

Amino Acid ◽

Influenza A ◽

Amino Acid Change ◽

Reverse Genetics ◽

Single Gene ◽

Neuraminidase Inhibitor ◽

Influenza B Virus ◽

Influenza B ◽

B Virus

ABSTRACT The recovery of recombinant influenza A virus entirely from cDNA was recently described (9, 19). We adapted the technique for engineering influenza B virus and generated a mutant bearing an amino acid change E116G in the viral neuraminidase which was resistant in vitro to the neuraminidase inhibitor zanamivir. The method also facilitates rapid isolation of single-gene reassortants suitable as vaccine seeds and will aid further investigations of unique features of influenza B virus.

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Development of an Alternative Modified Live Influenza B Virus Vaccine

Journal of Virology ◽

10.1128/jvi.00056-17 ◽

2017 ◽

Vol 91 (12) ◽

Cited By ~ 3

Author(s):

Jefferson J. S. Santos ◽

Courtney Finch ◽

Troy Sutton ◽

Adebimpe Obadan ◽

Isabel Aguirre ◽

...

Keyword(s):

Influenza A ◽

The United States ◽

Influenza B Virus ◽

Influenza B ◽

Temperature Sensitive ◽

Complete Protection ◽

C Terminus ◽

B Virus

ABSTRACT Influenza B virus (IBV) is considered a major human pathogen, responsible for seasonal epidemics of acute respiratory illness. Two antigenically distinct IBV hemagglutinin (HA) lineages cocirculate worldwide with little cross-reactivity. Live attenuated influenza virus (LAIV) vaccines have been shown to provide better cross-protective immune responses than inactivated vaccines by eliciting local mucosal immunity and systemic B cell- and T cell-mediated memory responses. We have shown previously that incorporation of temperature-sensitive (ts) mutations into the PB1 and PB2 subunits along with a modified HA epitope tag in the C terminus of PB1 resulted in influenza A viruses (IAV) that are safe and effective as modified live attenuated (att) virus vaccines (IAV att). We explored whether analogous mutations in the IBV polymerase subunits would result in a stable virus with an att phenotype. The PB1 subunit of the influenza B/Brisbane/60/2008 strain was used to incorporate ts mutations and a C-terminal HA tag. Such modifications resulted in a B/Bris att strain with ts characteristics in vitro and an att phenotype in vivo. Vaccination studies in mice showed that a single dose of the B/Bris att candidate stimulated sterilizing immunity against lethal homologous challenge and complete protection against heterologous challenge. These studies show the potential of an alternative LAIV platform for the development of IBV vaccines. IMPORTANCE A number of issues with regard to the effectiveness of the LAIV vaccine licensed in the United States (FluMist) have arisen over the past three seasons (2013–2014, 2014–2015, and 2015–2016). While the reasons for the limited robustness of the vaccine-elicited immune response remain controversial, this problem highlights the critical importance of continued investment in LAIV development and creates an opportunity to improve current strategies so as to develop more efficacious vaccines. Our laboratory has developed an alternative strategy, the incorporation of 2 amino acid mutations and a modified HA tag at the C terminus of PB1, which is sufficient to attenuate the IBV. As a LAIV, this novel vaccine provides complete protection against IBV strains. The availability of attenuated IAV and IBV backbones based on contemporary strains offers alternative platforms for the development of LAIVs that may overcome current limitations.

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Transcriptome profiling and protease inhibition experiments identify proteases that activate H3N2 influenza A and influenza B viruses in murine airways

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.012635 ◽

2020 ◽

Vol 295 (33) ◽

pp. 11388-11407 ◽

Cited By ~ 5

Author(s):

Anne Harbig ◽

Marco Mernberger ◽

Linda Bittel ◽

Stephan Pleschka ◽

Klaus Schughart ◽

...

Keyword(s):

Influenza A ◽

Transcriptome Profiling ◽

Alveolar Epithelial Cells ◽

Lower Airway ◽

Mouse Lung ◽

Influenza B ◽

Virus Infectivity ◽

Protease Inhibition ◽

Deficient Mice

Cleavage of influenza virus hemagglutinin (HA) by host proteases is essential for virus infectivity. HA of most influenza A and B (IAV/IBV) viruses is cleaved at a monobasic motif by trypsin-like proteases. Previous studies have reported that transmembrane serine protease 2 (TMPRSS2) is essential for activation of H7N9 and H1N1pdm IAV in mice but that H3N2 IAV and IBV activation is independent of TMPRSS2 and carried out by as-yet-undetermined protease(s). Here, to identify additional H3 IAV- and IBV-activating proteases, we used RNA-Seq to investigate the protease repertoire of murine lower airway tissues, primary type II alveolar epithelial cells (AECIIs), and the mouse lung cell line MLE-15. Among 13 candidates identified, TMPRSS4, TMPRSS13, hepsin, and prostasin activated H3 and IBV HA in vitro. IBV activation and replication was reduced in AECIIs from Tmprss2/Tmprss4-deficient mice compared with WT or Tmprss2-deficient mice, indicating that murine TMPRSS4 is involved in IBV activation. Multicycle replication of H3N2 IAV and IBV in AECIIs of Tmprss2/Tmprss4-deficient mice varied in sensitivity to protease inhibitors, indicating that different, but overlapping, sets of murine proteases facilitate H3 and IBV HA cleavages. Interestingly, human hepsin and prostasin orthologs did not activate H3, but they did activate IBV HA in vitro. Our results indicate that TMPRSS4 is an IBV-activating protease in murine AECIIs and suggest that TMPRSS13, hepsin, and prostasin cleave H3 and IBV HA in mice. They further show that hepsin and prostasin orthologs might contribute to the differences observed in TMPRSS2-independent activation of H3 in murine and human airways.

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Hsa-miR-30e-3p inhibits influenza B virus replication by targeting viral NA and NP genes

Experimental Biology and Medicine ◽

10.1177/1535370220953151 ◽

2020 ◽

Vol 245 (18) ◽

pp. 1664-1671

Author(s):

Kritsada Khongnomnan ◽

Suthat Saengchoowong ◽

Oraphan Mayuramart ◽

Pattaraporn Nimsamer ◽

Trairak Pisitkun ◽

...

Keyword(s):

Virus Infection ◽

Influenza A ◽

Influenza Virus Infection ◽

Influenza B Virus ◽

Influenza B ◽

Cellular Processes ◽

In Vitro Investigation ◽

B Virus ◽

Non Coding Rnas

Influenza B virus is a member of the Orthomyxoviridae family which can infect humans and causes influenza. Although it is not pandemic like influenza A virus, it nevertheless affects millions of people worldwide annually. MicroRNAs are small non-coding RNAs regulating gene expression at posttranscriptional level. They play various important roles in cellular processes including response to viral infection. MiRNA profiles from our previous study suggested that miR-30e-3p was one of the upregulated miRNAs that responded to influenza B virus infection. In this study, in silico prediction and in vitro investigation proved that this miRNA can directly target NA and NP genes of the influenza B virus and inhibit its replication. This finding might be useful for using miRNA as an alternative therapeutics for influenza virus infection.

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Inhibitory effects of aprotinin on influenza A and B viruses in vitro and in vivo

Scientific Reports ◽

10.1038/s41598-021-88886-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Eun-Jung Song ◽

Erica Españo ◽

Sang-Mu Shim ◽

Jeong-Hyun Nam ◽

Jiyeon Kim ◽

...

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Lethal Dose ◽

Influenza Viruses ◽

Influenza B Virus ◽

Influenza B ◽

Inhibitory Effects ◽

Compound Libraries ◽

Wide Range

AbstractInfluenza viruses cause significant morbidity and mortality worldwide. Long-term or frequent use of approved anti-influenza agents has resulted in drug-resistant strains, thereby necessitating the discovery of new drugs. In this study, we found aprotinin, a serine protease inhibitor, as an anti-influenza candidate through screening of compound libraries. Aprotinin has been previously reported to show inhibitory effects on a few influenza A virus (IAV) subtypes (e.g., seasonal H1N1 and H3N2). However, because there were no reports of its inhibitory effects on the other types of influenza viruses, we investigated the inhibitory effects of aprotinin in vitro on a wide range of influenza viruses, including avian and oseltamivir-resistant influenza virus strains. Our cell-based assay showed that aprotinin had inhibitory effects on seasonal human IAVs (H1N1 and H3N2 subtypes), avian IAVs (H5N2, H6N5, and H9N2 subtypes), an oseltamivir-resistant IAV, and a currently circulating influenza B virus. We have also confirmed its activity in mice infected with a lethal dose of influenza virus, showing a significant increase in survival rate. Our findings suggest that aprotinin has the capacity to inhibit a wide range of influenza virus subtypes and should be considered for development as a therapeutic agent against influenza.

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The memberane Piece Technique for in Vitro Infectivity Titrations of Influenza Virus

Journal of Hygiene ◽

10.1017/s0022172400037323 ◽

1957 ◽

Vol 55 (3) ◽

pp. 434-456 ◽

Cited By ~ 7

Author(s):

N. B. Finter ◽

P. Armitage

Keyword(s):

Influenza Virus ◽

Influenza A ◽

Technical Assistance ◽

Allantoic Fluid ◽

Test Tube ◽

Influenza B Virus ◽

Influenza B ◽

Experimental Conditions ◽

Set Up

1. The membrane piece technique for in vitro titrations of the infectivity of influenza virus is described. Rectangles of shell, about 8 × 25 mm., with the chorio-allantoic membrane still attached (membrane pieces) are cut from thirteenth-day fertile eggs. One piece in a test-tube with glucose-buffered salt solution forms an individual assay unit. Five or more tubes are inoculated with each virus dilution. After incubation at 37° C. for 72 hr., with agitation for the first 24 hr. the fluid in each tube is tested for haemagglutinins. From the results at each dilution, an estimate of the 50% membrane piece (MP50) infectivity titre is obtained.2. Six hundred assay units, with pieces cut from twenty eggs, can be set up by two workers in 1 hr. and used for titration of between three and twenty-four individual virus preparations, depending on the reliability desired for the 50% end-point estimates.3. With the D.S.P. and PR 8 strains of influenza A virus, the MP50 titres parallel the EID50 titres from egg titrations, but are eight times and twenty times lower, respectively. The MP50: EID50 ratio is the same for various preparations of the same strain, including standard allantoic fluid and chorio-allantoic membrane virus, incomplete virus, and inactivated (heated) allantoic fluid virus. Preliminary experiments with Lee influenza B virus show that slightly different experimental conditions are required, and the MP50 titres are about fifty times less than the EID50 titres.4. Consistent results have been obtained on titration of samples of the same virus preparation on a number of occasions over a period of several months.5. A large number of membrane pieces can be used to test each virus dilution, and sampling variations in the MP50 estimates thus made quite small. Statistical data on the reliability of a 50 % titration result, and on the minimum significant differences between two end-points, are given for different values of n, the number of membrane pieces used to test each virus dilution, and of d, the log dilution step.We are grateful to Mr J. Collins for invaluable technical assistance, and also to Miss I. Allen for help with the computations.

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Kinetics Of Interferon-λ And Receptor Expression In Response To In Vitro Respiratory Viral Infection

10.1101/2021.12.30.474514 ◽

2021 ◽

Author(s):

Alexey Lozhkov ◽

Nikita Yolshin ◽

Irina Baranovskaya ◽

Marina Plotnikova ◽

Mariia Sergeeva ◽

...

Keyword(s):

Influenza A ◽

Alveolar Epithelial Cell ◽

Mrna Level ◽

Receptor Expression ◽

Influenza B Virus ◽

Influenza B ◽

Type I ◽

Viral Spread ◽

Syncytial Virus

The major protective immune response against viruses is production of type I and III interferons (IFNs). IFNs induce the expression of hundreds of IFN-stimulated genes (ISGs) that block viral replication and further viral spread. The ability of respiratory viruses to suppress induction of IFN-mediated antiviral defenses in infected epithelial cells may be a factor contributing to the particular pathogenicity of several strains. In this report, we analyzed expression of IFNs and some ISGs in an alveolar epithelial cell subtype (A549) in response to infection with: influenza A viruses (A/California/07/09pdm (H1N1), A/Texas/50/12 (H3N2)); influenza B virus (B/Phuket/3073/13); adenovirus type 5 and 6; or respiratory syncytial virus (strain A2). IFNL and ISGs expression significantly increased in response to infection with all RNA viruses 24 hpi. Nevertheless, only IBV led to early increase in IFNL and ISGs mRNA level. IBV and H1N1 infection led to elevated proinflammatory cytokine production. We speculate that augmented IFN-α, IFN-β, IL-6 levels negatively correlate to SOCS1 expression. Importantly, we showed a decrease in IFNLR1 mRNA in case of IBV infection that implies the existence of negative ISGs expression regulation at IFNλR level. It could be either a specific feature of IBV or a consequence of early IFNL expression.

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Eosinophil Responses at the Airway Epithelial Barrier during the Early Phase of Influenza a Virus Infection in C57BL/6 Mice

Cells ◽

10.3390/cells10030509 ◽

2021 ◽

Vol 10 (3) ◽

pp. 509 ◽

Cited By ~ 1

Author(s):

Meenakshi Tiwary ◽

Robert J. Rooney ◽

Swantje Liedmann ◽

Kim S. LeMessurier ◽

Amali E. Samarasinghe

Keyword(s):

Epithelial Cells ◽

Influenza A Virus ◽

Early Phase ◽

Influenza A ◽

Airway Epithelial Cells ◽

Epithelial Barrier ◽

Virus Infectivity ◽

Airway Epithelial ◽

In Vivo Models

Eosinophils, previously considered terminally differentiated effector cells, have multifaceted functions in tissues. We previously found that allergic mice with eosinophil-rich inflammation were protected from severe influenza and discovered specialized antiviral effector functions for eosinophils including promoting cellular immunity during influenza. In this study, we hypothesized that eosinophil responses during the early phase of influenza contribute to host protection. Using in vitro and in vivo models, we found that eosinophils were rapidly and dynamically regulated upon influenza A virus (IAV) exposure to gain migratory capabilities to traffic to lymphoid organs after pulmonary infection. Eosinophils were capable of neutralizing virus upon contact and combinations of eosinophil granule proteins reduced virus infectivity through hemagglutinin inactivation. Bi-directional crosstalk between IAV-exposed epithelial cells and eosinophils occurred after IAV infection and cross-regulation promoted barrier responses to improve antiviral defenses in airway epithelial cells. Direct interactions between eosinophils and airway epithelial cells after IAV infection prevented virus-induced cytopathology in airway epithelial cells in vitro, and eosinophil recipient IAV-infected mice also maintained normal airway epithelial cell morphology. Our data suggest that eosinophils are important in the early phase of IAV infection providing immediate protection to the epithelial barrier until adaptive immune responses are deployed during influenza.

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QUALITATIVE DIFFERENCES IN THE ANTIGENIC COMPOSITION OF INFLUENZA A VIRUS STRAINS

Journal of Experimental Medicine ◽

10.1084/jem.79.6.633 ◽

1944 ◽

Vol 79 (6) ◽

pp. 633-647 ◽

Cited By ~ 18

Author(s):

William F. Friedewald

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Serum Antibody ◽

Allantoic Fluid ◽

Influenza B Virus ◽

Influenza B ◽

Red Cell ◽

Homologous Virus ◽

Cell Adsorption ◽

Virus Strains

A study of the PR8, Christie, Talmey, W.S., and swine strains of influenza A virus by means of antibody absorption tests revealed the following findings: 1. Serum antibody could be specifically absorbed with allantoic fluid containing influenza virus or, more effectively, with concentrated suspensions of virus obtained from allantoic fluid by high-speed centrifugation or by the red cell adsorption and elution technique. Normal allantoic fluid, or the centrifugalized sediment therefrom, failed to absorb antibodies. Influenza B virus (Lee) caused no detectable absorption of antibody from antisera directed against influenza A virus strains, but it specifically absorbed antibody from Lee antisera. 2. The neutralizing, agglutination-inhibiting, and complement-fixing anti-bodies in ferret antisera were completely absorbed only by the homologous virus strain, even though 2 absorptions were carried out with large amounts of heterologous virus strains. 3. PR8 virus appeared to have the broadest range of specific antigenic components for it completely absorbed the heterologous antibodies in Christie and W.S. antisera and left only those antibodies which reacted with the respective homologous strains. The other virus strains (Christie, Talmey, W.S., swine) were more specific in the absorption of heterologous antibodies and completely removed only those antibodies which reacted with the absorbing virus. 4. The absorption tests revealed a higher degree of specificity and individuality of the virus strains than the various cross reactions previously reported. The strain specificity of PR8 virus was equally manifest in absorption tests with ferret sera and with human sera following vaccination. 5. The amount of homologous antibody remaining in a PR8 ferret serum after absorption with PR8 virus, obtained by the red cell adsorption and elution method, varied inversely as the concentration of virus used for absorption. A given concentration of virus, however, absorbed a greater percentage of neutralizing antibodies than either agglutination-inhibiting or complement-fixing antibodies.

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