Kallistatin Ameliorates Influenza Virus Pathogenesis by Inhibition of Kallikrein-Related Peptidase 1-Mediated Cleavage of Viral Hemagglutinin (original) (raw)
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Journal of Virology, 2006
Host cell proteases that cleave the hemagglutinin (HA) of influenza viruses in the human respiratory tract are still not identified. Here we cloned two human type II transmembrane serine proteases with known airway localization, TMPRSS2 and HAT, into mammalian expression vector. Cotransfection of mammalian cells with plasmids encoding HA and either protease resulted in HA cleavage in situ. Transient expression of either protease in MDCK cells enabled multicycle replication of influenza viruses in these cells in the absence of exogenous trypsin. These data suggest that TMPRSS2 and HAT are candidates for proteolytic activation of influenza viruses in vivo.
Vaccine, 2009
Cleavage of the influenza virus hemagglutinin (HA) by host cell proteases is essential for virus infectivity and, therefore, relevant proteases may present promising new drug targets. We recently demonstrated that serine proteases TMPRSS2 and HAT from human airways activate influenza virus HA with monobasic cleavage site in vitro. In the present study we generated MDCK cells with inducible expression of either TMPRSS2 or HAT. MDCK-TMPRSS2 and MDCK-HAT cells supported growth of human and avian influenza viruses of different subtypes in the absence of exogenous trypsin. Further, we used these cell lines to investigate the efficacy of protease inhibitors to prevent proteolytic activation of HA by TMPRSS2 and HAT. Multicycle viral replication in both cell lines was markedly suppressed in the presence of serine protease inhibitors and we found that particularly in MDCK-HAT cells proteolytic activation of progeny viruses was very susceptible to inhibitor treatment. Taken together, our data demonstrate that MDCK-HAT and MDCK-TMPRSS2 cells are useful experimental systems to study cleavage of HA by host cell protease and its inhibition and in addition represent applicable cell lines to propagate influenza viruses in the absence of trypsin.
Cleavage of influenza virus hemagglutinin by host cell proteases
International Congress Series, 2004
A full-length gene of tryptase TMPRSS2 was cloned from total RNA of human tracheobronchial epithelial (HTBE) cells. The TMRSS2 protein was expressed in Escherichia coli as two truncated forms. Recombinant TMPRSS2 was enzymatically active, cleaved influenza A virus hemagglutinin and activated multi-cycle virus replication in MDCK cells. Thus, TMPRSS2 is an appropriate tryptase candidate for the HA-activation of influenza A viruses in vivo. D 2004 Published by Elsevier B.V.
Inhibition of influenza virus infection and hemagglutinin cleavage by the protease inhibitor HAI-2
Biochemical and Biophysical Research Communications, 2014
Influenza virus remains a significant concern to public health, with the continued potential for a high fatality pandemic. Vaccination and antiviral therapeutics are effective measures to circumvent influenza virus infection, however, multiple strains have emerged that are resistant to the antiviral therapeutics currently on the market. With this considered, investigation of alternative antiviral therapeutics is being conducted. One such approach is to inhibit cleavage activation of the influenza virus hemagglutinin (HA), which is an essential step in the viral replication cycle that permits viral-endosome fusion. Therefore, targeting trypsin-like, host proteases responsible for HA cleavage in vivo may prove to be an effective therapeutic. Hepatocyte growth factor activator inhibitor 2 (HAI-2) is naturally expressed in the respiratory tract and is a potent inhibitor of trypsin-like serine proteases, some of which have been determined to cleave HA. In this study, we demonstrate that HAI-2 is an effective inhibitor of cleavage of HA from the human-adapted H1 and H3 subtypes. HAI-2 inhibited influenza virus H1N1 infection in cell culture, and HAI-2 administration showed protection in a mouse model of influenza. HAI-2 has the potential to be an effective, alternative antiviral therapeutic for influenza.
Vaccine, 2012
Cleavage of the influenza virus hemagglutinin (HA) by host cell proteases is crucial for infectivity and spread of the virus. Some years ago, we identified TMPRSS2 and HAT from human airways as activating proteases of influenza A viruses containing a monobasic HA cleavage site. Therefore, these proteases are considered as potential drug targets. In this report, first we show that HA of influenza B virus is activated by TMPRSS2 and HAT, too. We further demonstrate that benzylsulfonyl-d-arginine-proline-4-amidinobenzylamide (BAPA), which is a potent inhibitor of HAT and TMPRSS2, efficiently suppresses virus propagation in TMPRSS2-expressing human airway epithelial cells by inhibition of HA cleavage. BAPA treatment reduced virus titers of different influenza A and B viruses more than 1000-fold and delayed virus propagation by 24-48 h at non-cytotoxic concentrations. A combination of BAPA with the neuraminidase (NA) inhibitor oseltamivir carboxylate efficiently blocked influenza virus replication in airway epithelial cells at remarkable lower concentrations for each compound than treatment with either inhibitor alone. Our studies provide a novel and potent approach for influenza chemotherapy that should be considered for influenza treatment.
Pathogens and disease, 2013
Influenza is an acute infection of the respiratory tract, which affects each year millions of people. Influenza virus infection is initiated by the surface glycoprotein hemagglutinin (HA) through receptor binding and fusion of viral and endosomal membranes. HA is synthesized as a precursor protein and requires cleavage by host cell proteases to gain its fusion capacity. Although cleavage of HA is crucial for virus infectivity, little was known about relevant proteases in the human airways for a long time. Recent progress in the identification and characterization of HA-activating host cell proteases has been considerable however and supports the idea of targeting HA cleavage as a novel approach for influenza treatment. Interestingly, certain bacteria have been demonstrated to support HA activation either by secreting proteases that cleave HA or due to activation of cellular proteases and thereby may contribute to virus spread and enhanced pathogenicity. In this review, we give an ov...
Virology, 1989
Lysates of cultured cells have been analyzed for arginine-specific endoproteases using peptidyl-p-nitroanilides as chromogenic substrates. The enzymes present in MDBK, MDCK, VERO, BHK, and chick embryo cells required lysinearginine or arginine-arginine pairs as cleavage sites, whereas chorioallantoic membrane cells contained, in addition, an activity that could cleave at a single arginine. The effect of peptidyl chloroalkyl ketones on the activation of the fowl plague virus hemagglutinin by the proteases specific for paired basic residues has been investigated. When virions containing uncleaved hemagglutinin were incubated with lysates of uninfected cells, cleavage was completely inhibited by peptidyl chloroalkyl ketones containing paired basic residues at a concentration of 1 mM. In contrast a compound containing a single arginine had no inhibitory activity. When dibasic peptidyl chloroalkyl ketones were added to infected cell cultures, cleavage of hemagglutinin and multiple cycles of virus replication were inhibited at 10 mM. However, a 1 OO-to 200-fold increase of the inhibitory activity in intact cells could be achieved by N-terminal acylation. These studies suggest a potential role of peptidyl chloroalkyl ketones as antiviral agents. Q 1989Academic PWS. I~C.
Journal of Virology, 2010
Host cellular proteases induce influenza virus entry into cells by cleaving the viral surface envelope glycoprotein hemagglutinin (HA). However, details on the cellular proteases involved in this event are not fully available. We report here that ubiquitous type II transmembrane serine proteases, MSPL and its splice variant TMPRSS13, are novel candidates for proteases processing HA proteins of highly pathogenic avian influenza (HPAI) viruses, apart from the previously identified furin and proprotein convertases 5 and 6. HAs from all HPAI virus H5 and H7 strains have one of two cleavage site motifs, the R -X-K/R-R motif with R at position P4 and the K -K/R-K/T-R motif with K at position P4. In studies of synthetic 14-residue HPAI virus HA peptides with these cleavage site motifs, furin preferentially cleaved only HA peptides with the R -K-K-R motif in the presence of calcium and not peptides with the other motif, whereas MSPL and TMPRSS13 cleaved both types of HA peptides (those with...