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Updated: May 28, 2026
Isolation And Dendritic Cell-Uptake of Small Extracellular Vesicles from Echinococcus granulosus
Published on: March 28, 2025
Echinococcus multilocularis serine protease inhibitor 1 (EmSPI-1): a highly effective serodiagnostic antigen for
Mengxiao Tian1, Jun Li2, Chuanchuan Wu3
1Basic Medicine College, Xinjiang Medical University, Urumqi, Xinjiang, China.
Background:
Alveolar echinococcosis (AE), caused by Echinococcus multilocularis, is a lethal zoonotic disease. Population screening for early diagnosis is crucial for effective treatment, and novel diagnostic antigens are needed for diagnostic purposes.
Methods:
E. multilocularis serine protease inhibitor 1 (EmSPI-1) was cloned and expressed in Escherichia coli. Quantitative real-time PCR (qRT-PCR) and Western blotting were used to assess gene expression at different life-cycle stages of the tapeworm. The diagnostic potential of recombinant EmSPI-1 (rEmSPI-1) was evaluated by enzyme-linked immunosorbent assay (ELISA) and Western blotting using sera from patients with AE and individuals with other infectious diseases, and healthy controls.
Results:
Soluble recombinant EmSPI-1 (rEmSPI-1) was successfully expressed in E. coli cultured at 15 °C. Protein sequence alignment and structural analysis demonstrated 100% identity between EmSPI-1 and EgSPI-1 (EGR_03125), both containing conserved serpin domains with α-helices and a reactive center loop. Stage expression results demonstrated that EmSPI-1 was highly expressed in the germinal layer (GL) of the cyst, pepsin-treated protoscoleces (PSCs) and adult worms (AW). Notably, rEmSPI-1 induced a dominant IgG4 antibody response in sera from AE patients. A diagnostic assay using ELISA showed 90.37% sensitivity (122/135) and 96.24% specificity among 638 non-AE serum samples. Receiver operating characteristic (ROC) curve analysis yielded an area under the curve (AUC) of 0.942 (95% CI: 0.921-0.963) for differentiating AE patients from healthy controls, and an AUC of 0.971 for distinguishing AE from non-AE infectious samples. For WHO-IWGE early-stage AE (P1N0M0 + P2N1M0 + P2N1M1, n = 15), rEmSPI-1 showed a sensitivity of 80.0% (12/15). The P1N0M0 subgroup (n = 4) showed a sensitivity of 25.0% for rEmSPI-1 and 0% for rEm18.
Conclusions:
EmSPI-1 is highly expressed in the AW, GL, and PSCs of E. multilocularis and serves as a serodiagnostic biomarker for detecting IgG4 antibodies in the sera of AE patients, with 90.37% sensitivity and 96.24% of specificity.
