The cysteine protease ATG4B of Trichinella spiralis promotes larval invasion into the intestine of the host

In this study, we analysed the cysteine protease ATG4B ofTrichinella spiralis (TsATG4B) isolated from the soluble proteins ofTrichinella spiralis (T. spiralis) adult worms to ascertain its biochemical properties and functions during invasion into the intestine of the host. The 43  kDa recombinant cysteine protease ATG4B protein (rTsATG4B) consists of a conserved peptidase_C54 domain and was expressed inEscherichia coli. Gelatine zymography showed that rTsATG4B could hydrolyse gelatine and that the hydrolytic activity was prevented by the cysteine protease inhibitor E-64 (pH 5.2). Immunofluorescence assays showed that TsATG4B is expressed at different stages and is localized at the cuticles and stichosomes of worms. Far-Western blotting and confocal microscopy revealed that rTsATG4B interacts with intestinal epithelial cells (IECs) and that it was subcellularly localized to the membrane and cytoplasm in IECs. Real ‑time quantitative PCR (qPCR) results indicated that the transcription level of the TsATG4B gene was the higher in 6-day-old adult worms (6 days AW) than in any other stage. An in vitro larval invasion assay verified that rTsATG4B promoted larval invasion and that invasion was inhibited when rTsA TG4B was pre-incubated with E-64, whereas anti-rTsATG4B serum inhibited larval invasion in a dose-dependent manner. Collectively, these results suggested that the enzymatic activity of TsATG4B significantly influences the hydrolysis process, which is necessary for larval...
Source: Veterinary Research - Category: Veterinary Research Source Type: research