Cathepsin L is one member of cysteine protease superfamily and widely distributed in parasitic organisms, it plays the important roles in worm invasion, migration, nutrient intake, molting and immune evasion. The objective of this study was to investigate the biological characteristics of a novel cathepsin L from Trichinella spiralis (TsCL) and its role in larval invasion, development and reproduction. TsCL has a functional domain of C1 peptidase, which belongs to cathepsin L family. The complete TsCL sequence was cloned and expressed in Escherichia coli BL21. The rTsCL has good immunogenicity. RT-PCR and Western blotting analysis showed that TsCL was transcribed and expressed at different T. spiralis phases (e.g., muscle larvae, intestinal infectious larvae, adult worms and newborn larvae). Immunofluorescence test revealed that TsCL was principally localized in the cuticle, stichosome, midgut and female intrauterine embryos of the nematode. rTsCL has the capacity to specially bind with intestinal epithelial cells (IECs) and the binding sites was located in the cytoplasm. rTsCL promoted larval penetration into IEC, while anti-rTsCL antibodies inhibited the invasion. The silencing of TsCL gene by specific dsRNA significantly reduced the TsCL expression and enzyme activity, and also reduced larval invasive ability, development and female reproduction. The results showed that TsCL is an obligatory protease in T. spiralis lifecycle. TsCL participates in worm invasion, development and reproduction, and may be regarded as a potential candidate vaccine/drug target against T. spiralis infection.

组织蛋白酶L是半胱氨酸蛋白酶超家族的一员，广泛分布于寄生生物中，在蠕虫入侵、迁移、营养摄取、蜕皮和免疫逃避等方面发挥重要作用。本研究的目的是研究一种来自旋毛虫(TsCL)的新型组织蛋白酶 L 的生物学特性及其在幼虫入侵、发育和繁殖中的作用。TsCL 具有 C1 肽酶的功能域，属于组织蛋白酶 L 家族。完整的 TsCL 序列被克隆并在大肠杆菌BL21中表达。rTsCL 具有良好的免疫原性。RT-PCR和Western blotting分析表明，TsCL在不同的旋毛虫中转录表达阶段（例如，肌肉幼虫、肠道感染性幼虫、成虫和新生幼虫）。免疫荧光试验表明，TsCL 主要定位于线虫的角质层、针状体、中肠和雌性宫内胚胎中。rTsCL 具有与肠上皮细胞 (IEC) 特异性结合的能力，结合位点位于细胞质中。rTsCL 促进幼虫侵入 IEC，而抗 rTsCL 抗体抑制侵入。特定dsRNA对TsCL基因的沉默显着降低了TsCL表达和酶活性，也降低了幼虫的侵袭能力、发育和雌性繁殖。结果表明 TsCL 是T. spinis 中的一种必需蛋白酶生命周期。TsCL 参与蠕虫的入侵、发育和繁殖，可被视为针对螺旋线虫感染的潜在候选疫苗/药物靶点。