SPINT2 inhibits proteases involved in activation of both influenza viruses and metapneumoviruses

Abstract

A B S T R A C TViruses possessing class I fusion proteins require proteolytic activation by host cell proteases to mediate fusion with the host cell membrane. The mammalian SPINT2 gene encodes a protease inhibitor that targets trypsin-like serine proteases. Here we show the protease inhibitor, SPINT2, restricts cleavage-activation efficiently for a range of influenza viruses and for human metapneumovirus (HMPV). SPINT2 treatment resulted in the cleavage and fusion inhibition of full-length influenza A/CA/04/09 (H1N1) HA, A/Aichi/68 (H3N2) HA, A/Shanghai/2/ 2013 (H7N9) HA and HMPV F when activated by trypsin, recombinant matriptase or KLK5. We also demonstrate that SPINT2 was able to reduce viral growth of influenza A/CA/04/09 H1N1 and A/X31 H3N2 in cell culture by inhibiting matriptase or TMPRSS2. Moreover, inhibition efficacy did not differ whether SPINT2 was added at the time of infection or 24 h post-infection. Our data suggest that the SPINT2 inhibitor has a strong potential to serve as a novel broad-spectrum antiviral.

COVID-19: Targeting Proteases in Viral Invasion and Host Immune Response

“…Further, full inhibition was observed when the camostat mesylate was coupled with Cathepsin B/L inhibitor E-64d, indicating alternate protein priming by endosomal cysteine proteases Cathepsin B/L (Hoffmann et al, 2020). These results were in concert with another study where SPINT2 geneencoded protease inhibitor targeted TMPRSS2 and led to the restriction of cleavage-activation and viral growth for a range of influenza viruses (Straus et al, 2020). Furthermore, the role of KLK1 and KLK5 in influenza viral infection enhancement and its inhibition by Kallistatin was well established by Leu et al (2015) and Magnen et al (2017).…”

Bioinformatics analyses of significant genes, related pathways, and candidate diagnostic biomarkers and molecular targets in SARS-CoV-2/COVID-19

“…Genes such as IFIT1 [ Feng et al, 2018 ], XAF1 [ Long et al, 2013 ], OAS3 [ Gad et al, 2012 ], CKB (creatine kinase B) [ Hara et al, 2009 ], RPL18A [ B. Wang et al, 2018 ], CIB1 [ Godinho-Santos et al, 2016 ] and EEF2 [ Valiente-Echeverría et al, 2014 ] were linked with advancement of various viral infections, but these genes may be liable for progression of SARS-CoV-2 infection. Genes such as OAS2 [ Zhao et al, 2019 ], CXCL10 [ Law et al, 2010 ] and SPINT2 [ Straus et al, 2020 ] were linked with progression of influenza virus infection, but these genes may be associated with development of SARS-CoV-2 infection.…”

Priming of SARS-CoV-2 S protein by several membrane-bound serine proteinases could explain enhanced viral infectivity and systemic COVID-19 infection

“…Kinetic analysis has been reported so far for hepsin inhibition by the first Kunitz domain of HAI-1 ( 54 ) as well as for the matriptase-HAI-1 pair ( 55 , 56 ). In addition, HAI-1 and/or HAI-2 have been identified as physiologically relevant inhibitors of hepsin ( 50 ), TMPRSS2 ( 57 , 58 , 59 ), TMPRSS3 ( 57 ), TMPRSS4 ( 57 , 60 ), matriptase-2 ( 61 , 62 ), HATL1/TMPRSS11A ( 57 ), HAT/TMPRSS11D ( 63 ), DESC1/TMPRSS11E ( 64 ), TMPRSS13 ( 53 , 57 , 65 ), matriptase ( 58 , 60 , 66 , 67 , 68 , 69 , 70 ), enteropeptidase/TMPRSS15 ( 57 ), and prostasin ( 68 , 71 , 72 , 73 ). In fact, HAI-2 has been recently proposed as a broad-spectrum antiviral agent ( 58 ).…”

“…Thus, HAI-1 and HAI-2, as master regulators of all MASPs, would play an important role in SARS-CoV-2 propagation by regulating the availability of serine proteinase active sites on host cell membranes. Indeed, it has been recently shown that HAI-2 reduces cleavage/activation and growth of several influenza viruses by inhibiting TMPRSS2 or matriptase ( 58 ).…”