Tryptase Clara, an activating protease for Sendai virus in rat lungs, is involved in pneumopathogenicity

Abstract

Tryptase Clara is an arginine-specific serine protease localized exclusively in and secreted from Clara cells of the bronchial epithelium of rats (H.

Hendra and Nipah viruses: different and dangerous

“…By contrast, a small number of paramyxovirus F proteins are proteolytically cleaved by extracellular trypsin-like proteases that recognize a single basic residue at the cleavage site. Cleavage in vivo is achieved by trypsin-like proteases such as tryptase Clara and miniplasmin that have limited distributions and, as a result, viruses like Sendai virus (SeV) remain localized in the respiratory tract 73,74 . In view of the fact that henipaviruses generate systemic infections, it was surprising to find that the henipavirus F-protein cleavage site does not contain multiple basic residues.…”

TMPRSS2 Is an Activating Protease for Respiratory Parainfluenza Viruses

“…Trypsin is commonly used for the propagation of IAV, HMPV, SeV, HPIVs, and coronaviruses in cultured cells. Mini-plasmin found in bronchial epithelia (23), tryptase Clara from rat lungs (24,25), mast cell tryptase from porcine lungs (26), and factor Xa from chicken allantoic fluid (26) were shown to proteolytically activate IAV and SeV. Plasmin also activates IAV through unique mechanisms by which plasminogen is captured by the neuraminidase surface glycoprotein or host cell annexin II is incorporated into virions (27)(28)(29).…”

Nipah virus fusion protein: Influence of cleavage site mutations on the cleavability by cathepsin L, trypsin and furin

“…The most compelling evidence of a relationship between an intracellular ubiquitous cleavability of viral fusion proteins and systemic virus spread in vivo comes from naturally occurring strains of Newcastle disease virus and pneumotropic and pantropic Sendai virus variants as well as from studies on human and avian influenza viruses Peeters et al, 1999;Tashiro et al, 1988Tashiro et al, , 1990Tashiro et al, , 1992Tumpey et al, 2005). Even if viruses such as human parainfluenza virus type 2 and 3 (HPIV-2/3) or recombinant human metapneumovirus with an artificial furin cleavage site do not spread outside of the respiratory tract despite their furin-cleavable F proteins (Biacchesi et al, 2006;Ortmann et al, 1994;Sakaguchi et al, 1994), ubiquitous activation of the NiV F protein is clearly one of the indispensable prerequisites for systemic virus spread in vivo.…”

“…As a consequence, in vitro growth of viruses encoding fusion proteins with monobasic cleavage sites depends on the addition of trypsin to the cell culture medium. In vivo, replication of these viruses is restricted to the respiratory tract where suitable trypsinlike proteases are known to be expressed (Boettcher et al, 2006;Klenk and Garten, 1994;Tashiro et al, 1992). Although NiV and HeV possess F proteins with one basic amino acid at the cleavage site, virus infections are not restricted to the respiratory tract in vivo and do not require exogenous trypsin in cell culture (Chua et al, 1999;Hooper et al, 2001;Middleton et al, 2007;Moll et al, 2004a;Weingart et al, 2009).…”