1.Specific binding of aspartic protease and enterocytes promotes Trichinella spiralis invasion of murine intestinal epithelium cells
Xu, J. ; Xu, Y.X.Y. ; Yue, W.W. ; Hao, H.N. ; Liu, R.D. ; Long, S.R. ; Wang, Z.Q. ; Cui, J.
Tropical Biomedicine 2021;38(No.1):160-171
Trichinella spiralis is an important foodborne zoonotic parasite and it is necessary to develop
vaccine to prevent T. spiralis infection in food animals. T. spiralis aspartic protease-2 (TsASP2)
has been demonstrated to play a crucial role in larval invasion of intestinal epithelium
cells (IECs). The purpose of this study was to assess the interaction between TsASP2 and IECs
and to investigate the immune protection elicited by vaccination with rTsASP2. The results
showed that the enzymatic activity of native aspartic protease was detected in crude proteins
of all T. spiralis development stages other than NBL stage, the highest activity was observed
in the IIL stage. The results of Western blot showed that TsASP2 protein was expressed at
ML, IIL and AW but not NBL, and the TsASP2 expression level at IIL stage was significantly
higher than those of other three worm stages (P < 0.05). The specific binding between
rTsASP2 and IECs was observed by immunofluorescence test (IFT) and confocal microscopy,
and the binding site was localized at the IEC membrane and this binding ability was inhibited
by aspartic protease specific inhibitor pepstain A. The results of ELISA showed that the
binding ability was protein dose-dependent. Vaccination with rTsASP2 triggered a mixed
Th1/Th2 humoral and mucosal immune responses, as demonstrated by the elevation levels
of Th1/Th2 cytokines (IFN-γ and IL-4) secreted by the spleen and mesenteric lymph nodes
(MLNs) of immunized mice. The mice vaccinated with rTsASP2 exhibited a 54.17% reduction in
enteral adult worms and a 54.58% reduction in muscle larvae after T. spiralis challenge. The
results demonstrated that TsASP2 might be a potential molecular target for anti-Trichinella
vaccines.