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

Abstract

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 (AECII), 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 AECII from Tmprss2/Tmprss4-deficient mice compared with wild-type or Tmprss2-deficient mice, indicating that murine TMPRSS4 is involved in IBV activation. Multicycle replication of H3N2 IAV and IBV in AECII 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 did activate IBV HA in vitro. Our results indicate that TMPRSS4 is an IBV-activating protease in murine AECII 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.

Camostat mesylate inhibits SARS-CoV-2 activation by TMPRSS2-related proteases and its metabolite GBPA exerts antiviral activity

“…Whether these TTSPs play a role in viral spread in the host is incompletely understood. For IAV, infection by H3N2 viruses were found not to be fully TMPRSS2 dependent ( 38 , 42 ) and an auxiliary role of TMPRSS4 in spread and pathogenesis of H3N2 viruses has been reported ( 43 , 44 ). Moreover, influenza B viruses can use a broad range of TTSPs in cell culture ( 44 , 45 ) and a prominent role of TMPRSS2 in viral spread in type II pneumocytes has been reported ( 46 ) but viral spread in mice is TMPRSS2 independent ( 44 , 47 ).…”

Alpha 1 Antitrypsin is an Inhibitor of the SARS-CoV-2–Priming Protease TMPRSS2

“…TMPRSS2 has a role in the entry of several coronaviruses, including SARS-CoV2, SARS-CoV, and MERS-CoV, as well as several types of influenza viruses (2,(8)(9)(10)(11)(12). TMPRSS2 also functions as an oncogene in prostate cancer, in which fusion events of TMPRSS2 and ERG2 occur (13).…”

“…viruses in a murine model (8). Notably, these viruses do not require TMPRSS2 priming, and the mechanism of A1AT function was suggested to be mediated by hepsin inhibition.…”

In Silico Study of Curcumin and Folic Acid as Potent Inhibitors of Human Transmembrane Protease Serine 2 in the Treatment of COVID-19

“…Based on the findings, we found that TMPRSS2 protein is a highly effective target for the treatment of COVID-19 caused by SARS-CoV-2 [29]. As TMPRSS2 plays an important function in the entry of SARS-CoV-2, MERS-CoV-2, and some influenza viruses into the host cell [5,6,8,10], targeting TMPRSS2 will become a more direct approach to control the infectious diseases caused by these viruses.…”

“…It has been reported that TMPRSS2 played an important role in the progression of SARS, Middle East respiratory syndrome (MERS), and some influenza infections in a similar manner as SARS-CoV-2. [2,[4][5][6][7][8][9][10]. The increased viral genomic mutations result in multiple physiognomies of protein structure, which represent a challenge to counter viral resistance to drugs.…”