Schistosomiasis is still prevalent and seriously endangering the health of people and livestock in many countries. There have been great efforts to develop vaccines against schistosomiasis for prolonged protection in epidemic areas. Molecules from lung-stage schistosomula have been regarded as potential vaccine candidates against schistosomiasis. Our previous work has shown that cathepsin L3 from Schistosoma japonicum (SjCL3) is expressed in lung-stage schistosomula, but its role is not well known. In the present study, we characterized SjCL3 and detected its effect as a possible vaccine in vivo and in vitro. From the results of quantitative PCR (qPCR) and western blot, SjCL3 was present throughout the lifecycle of the worm, and its relative expressed level was higher in the liver eggs and adult worms than other stages. Additionally, immunofluorescence assay showed that SjCL3 was mainly concentrated in the eggshell, alimentary canal, and musculature of worms. Compared with the adjuvant group, the immunization of SjCL3 in mice resulted in a 28.9% decrease in worm burden and a 29.2% reduction in egg number in the host liver. In antibody-dependent cell-mediated cytotoxicity (ADCC) insecticidal experiments in vitro, the existence of SjCL3 could in part suppress adherence between macrophages and worm. The above results indicated that the immunization of SjCL3 could induce limited immune protection against S. japonicum infection in mice, and this protease played a role in breaking the process of ADCC, which was beneficial to the survival of worms.

中文翻译：

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日本血吸虫组织蛋白酶L3的特征和功能。

在许多国家，血吸虫病仍很普遍，严重危害着人和牲畜的健康。已经进行了巨大的努力来开发针对血吸虫病的疫苗，以在流行地区提供长期保护。来自肺血吸虫的分子被认为是抗血吸虫病的潜在候选疫苗。我们以前的工作表明，日本血吸虫的组织蛋白酶L3（SjCL3）在肺阶段血吸虫中表达，但其作用尚不清楚。在本研究中，我们表征了SjCL3并检测了其作为体内和体外可能疫苗的作用。从定量PCR（qPCR）和蛋白质印迹的结果来看，SjCL3存在于蠕虫的整个生命周期中，在肝脏卵和成虫中其相对表达水平高于其他阶段。另外，免疫荧光分析表明，SjCL3主要集中在蠕虫的蛋壳，消化道和肌肉组织中。与佐剂组相比，小鼠SjCL3的免疫导致宿主肝脏蠕虫负担减少28.9％，卵数减少29.2％。在体外抗体依赖性细胞介导的细胞毒性（ADCC）杀虫实验中，SjCL3的存在可以部分抑制巨噬细胞和蠕虫之间的粘附。上述结果表明，SjCL3的免疫可以诱导小鼠抗日本血吸虫感染的有限的免疫保护，并且该蛋白酶在破坏ADCC的过程中起作用，这有利于蠕虫的存活。与佐剂组相比，小鼠SjCL3的免疫导致宿主肝脏蠕虫负担减少28.9％，卵数减少29.2％。在体外抗体依赖性细胞介导的细胞毒性（ADCC）杀虫实验中，SjCL3的存在可以部分抑制巨噬细胞和蠕虫之间的粘附。上述结果表明，SjCL3的免疫可以诱导小鼠抗日本血吸虫感染的有限的免疫保护，并且该蛋白酶在破坏ADCC的过程中起作用，这有利于蠕虫的存活。与佐剂组相比，小鼠SjCL3的免疫导致宿主肝脏蠕虫负担减少28.9％，卵数减少29.2％。在体外抗体依赖性细胞介导的细胞毒性（ADCC）杀虫实验中，SjCL3的存在可以部分抑制巨噬细胞和蠕虫之间的粘附。上述结果表明，SjCL3的免疫可以诱导小鼠抗日本血吸虫感染的有限的免疫保护，并且该蛋白酶在破坏ADCC的过程中起作用，这有利于蠕虫的存活。SjCL3的存在可以部分抑制巨噬细胞和蠕虫之间的粘附。上述结果表明，SjCL3的免疫可以诱导小鼠抗日本血吸虫感染的有限的免疫保护，并且该蛋白酶在破坏ADCC的过程中起作用，这有利于蠕虫的存活。SjCL3的存在可以部分抑制巨噬细胞和蠕虫之间的粘附。上述结果表明，SjCL3的免疫可以诱导小鼠抗日本血吸虫感染的有限的免疫保护，并且该蛋白酶在破坏ADCC的过程中起作用，这有利于蠕虫的存活。