Abstract
BackgroundTrichinella spiralis is a major zoonotic tissue-dwelling nematode, which is a public health concern and a serious hazard to animal food safety. It is necessary to exploit an anti-Trichinella vaccine to interrupt the transmission of Trichinella infection among animals and from animals to humans. The purpose of the present study was to characterize the novel T. spiralis cathepsin B (TsCB) and to evaluate the immune protection elicited by immunization with recombinant TsCB (rTsCB).MethodsThe complete cDNA sequences of the TsCB gene were cloned, expressed and purified. The antigenicity of rTsCB was investigated by western blot analysis and ELISA. Transcription and expression of TsCB at various T. spiralis life-cycle stages were analyzed by RT-PCR and indirect immunofluorescent assay (IIFA). The mice were subcutaneously immunized with rTsCB, and serum level of TsCB-specific IgG (IgG1 and IgG2a) and IgE antibodies were assayed by ELISA. Immune protection elicited by vaccination with rTsCB was investigated.ResultsThe TsCB was transcribed and expressed in four T. spiralis life-cycle stages (adult worm, AW; newborn larvae, NBL; muscle larvae, ML; and intestinal infective L1 larvae), it was primarily located in the cuticle and stichosome of the parasitic nematode. Vaccination of mice with rTsCB produced a prominent antibody response (high level of specific IgG and IgE) and immune protection, as demonstrated by a 52.81% AW burden reduction of intestines at six days post-infection (dpi) and a 50.90% ML burden reduction of muscles at 35 dpi after oral larva challenge. The TsCB-specific antibody response elicited by immunization with rTsCB also impeded intestinal worm growth and decreased the female fecundity.ConclusionsTsCB might be considered as a novel potential molecular target to develop vaccines against T. spiralis infection.
Highlights
Trichinella spiralis is a major zoonotic tissue-dwelling nematode, which is a public health concern and a serious hazard to animal food safety
Analyses with Signal P 4.1 and TMHMM Server indicated that the signal peptide was located at 1–29 aa, T. spiralis cathepsin B (TsCB) had 7 α-helixes and 13 β-strands, and a transmembrane domain was located outside the cell membrane
The results showed that vaccination with recombinant TsCB (rTsCB) elicited specific IgE, which plays a major role in the rapid expulsion of intestinal infective larvae and adult worms from the guts of vaccinated animals and in delaying larva invasion of intestinal epithelium after oral infection [64, 65]
Summary
Trichinella spiralis is a major zoonotic tissue-dwelling nematode, which is a public health concern and a serious hazard to animal food safety. Infections with Trichinella spp. are not merely a public health concern and a severe hazard to animal food safety [6, 7]. T. spiralis ML encapsulate in the skeletal muscles and are released from their capsules in the stomach, where they develop into intestinal infective L1 larvae (IIL1) within the intestines. As intestinal epithelia are the preferential natural barrier against larval invasion, and the major site for host-T. spiralis interaction [14, 15], identification of IIL1 invasive proteins will be valuable to understand invasion mechanisms of the parasite and develop vaccines against T. spiralis intestinal invasive worms [16, 17]
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