Abstract
BackgroundTrichinella spiralis serine protease inhibitor (TsSPI) was identified in ES proteins of adult worms (AW), the TsSPI gene was highly expressed at enteral stage worms (AW and newborn larvae), distributed mainly in the cuticle and stichosome of this nematode. Vaccination of mice with rTsSPI exhibited a 62.2% reduction of intestinal AW and a 57.25% reduction of muscle larvae after larval challenge. The aim of this study was to investigate the biological characteristics of TsSPI and its roles in the process of T. spiralis invasion of host’s intestinal epithelium cells (IECs).MethodsThe rTsSPI inhibition on trypsin enzymatic activity was detected by SDS-PAGE and spectrophotometry. The binding of rTsSPI with intestinal epithelium from normal mice and the primary cultured mouse intestinal epithelium cells (IECs) was examined by indirect immunofluorescent (IIF), the cellular localization of rTsSPI binding to IECs was observed by confocal microscopy. The inhibition of anti-rTsSPI serum on T. spiralis invasion of IECs was determined by an in vitro invasion assay. Anti-rTsSPI antibody cytotoxicity on the newborn larvae (NBL) was also determined.ResultsThe rTsSPI had the inhibitory activity against porcine trypsin. The rTsSPI specifically bound to the intestinal epithelium from normal mice and primary cultured mouse IECs, and the binding sites were located in IEC membrane and cytoplasm. Anti-rTsSPI antibodies depressed the larval invasion of IECs with a dose-dependent mode. Anti-rTsSPI antibodies also participated in the destruction of T. spiralis NBL via an ADCC-mediated manner.ConclusionsTsSPI might participate in the T. spiralis larval invasion of IECs and it is likely the potential vaccine target against T. spiralis enteral stages.
Highlights
Trichinella spiralis serine protease inhibitor (TsSPI) was identified in ES proteins of adult worms (AW), the TsSPI gene was highly expressed at enteral stage worms (AW and newborn larvae), distributed mainly in the cuticle and stichosome of this nematode
Inhibition of trypsin hydrolysis of bovine serum albumin (BSA) by rTsSPI SDS-PAGE analysis revealed that 0.50 μg trypsin could degrade different concentrations of BSA (0.75–4.50 μg) (Fig. 1a) and rTsSPI (3.00–6.75 μg) (Fig. 1b); the trypsin hydrolysis of BSA could be inhibited by rTsSPI (6.00– 6.75 μg) (Fig. 1c)
The results revealed that the trypsin enzymatic activity was inhibited with rTsSPI
Summary
Trichinella spiralis serine protease inhibitor (TsSPI) was identified in ES proteins of adult worms (AW), the TsSPI gene was highly expressed at enteral stage worms (AW and newborn larvae), distributed mainly in the cuticle and stichosome of this nematode. The aim of this study was to investigate the biological characteristics of TsSPI and its roles in the process of T. spiralis invasion of host’s intestinal epithelium cells (IECs). Trichinellosis is a major zoonotic parasitosis resulted from the ingestion of raw or under-cooked meat infected with the nematodes Trichinella spp. When the contaminated meat is ingested by hosts, T. spiralis muscle larvae (ML) are liberated in stomach under the action of digestive enzymes, migrate to the. Song et al Parasites & Vectors (2018) 11:499 small intestine, and develop into intestinal first-stage infective larvae (IL1) [7, 8]. The IL1 invade intestinal epithelium cells (IECs) where they develop into female/ male adult worms (AW) after undergoing four molts within 31 h. The prevention and control of Trichinella infection should be to interrupt the IL1 lodge in IECs, to block larval development to AW and NBL production, to interdict NBL migration and to eliminate AW and NBL from the gut [12]
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