Alveolar echinococcosis, a parasitic zoonotic disease caused by the larval stage of Echinococcus multilocularis infection, is a global epidemic in Eurasia and North America. Leucine aminopeptidase (LAP) of the M17 peptidase family could act on an ideal target antigen in diagnosis and prevention of parasitic diseases (schistosomiasis, malaria, fascioliasis) because of its good immunogenicity. In this study, the bioinformatic and enzymatic characterizations of recombinant Echinococcus multilocularis LAP (rEm-LAP) were evaluated. A prokaryotic expression system for rEm-LAP protein was established and its immunogenicity and preventive efficacy were demonstrated in a BALB/c mice model. This is the first report about the LAP of Echinococcus multilocularis and with a 57.4 KD purified rEm-LAP protein successfully expressed by pCzn1-LAP in Escherichia coli BL-21 cells. Enzymatic analysis results showed optimal rEm-LAP activity at pH 9. Serum indirect ELISA demonstrated that rEm-LAP could induce a Th1 and Th2 mixed-type immunological response and produce high levels of IgG, IgG1, IgG2a, IgM, and IgA. Furthermore, serum IFN-γ and IL-4 secretion were increased compared with the control groups. Finally, vaccination with rEm-LAP significantly decreased both the number and size of the cysts in Echinococcus multilocularis metacestode infected mice model. The current study provides evidence that rEm-LAP could be a potential vaccine antigen of Echinococcus multilocularis.

肺泡棘球蚴病是一种由多房棘球蚴感染幼虫阶段引起的寄生虫病，是欧亚大陆和北美的全球流行病。M17 肽酶家族的亮氨酸氨肽酶 (LAP) 因其良好的免疫原性，可作用于诊断和预防寄生虫病（血吸虫病、疟疾、片吸虫病）的理想靶抗原。在这项研究中，评估了重组多房棘球绦虫LAP (rEm-LAP)的生物信息学和酶学特征。建立了rEm-LAP蛋白原核表达系统，并在BALB/c小鼠模型中证明了其免疫原性和预防功效。这是关于多房棘球绦虫LAP的首次报道pCzn1-LAP 在大肠杆菌BL-21 细胞中成功表达了 57.4 KD 的纯化 rEm-LAP 蛋白。酶促分析结果显示，在 pH 9 时具有最佳 rEm-LAP 活性。血清间接 ELISA 表明 rEm-LAP 可以诱导 Th1 和 Th2 混合型免疫反应，并产生高水平的 IgG、IgG1、IgG2a、IgM 和 IgA。此外，与对照组相比，血清 IFN-γ 和 IL-4 分泌增加。最后，接种 rEm-LAP 显着降低了多房棘球绦虫感染小鼠模型中包囊的数量和大小。目前的研究提供了证据，证明 rEm-LAP 可能是多房棘球绦虫的潜在疫苗抗原。