Choudhury Rajdeep, Das Partha, Bhaumik Siddhartha Kumar, De Tripti, Chakraborti Tapati
Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal.
Clin Vaccine Immunol. 2010 Apr;17(4):660-7. doi: 10.1128/CVI.00358-09. Epub 2010 Jan 27.
Proteases have been found to play essential roles in many biological processes, including the pathogenesis of leishmaniasis. Most parasites rely on their intracellular and extracellular protease repertoire to invade and multiply in mammalian host cells. However, few studies have addressed serine proteases in Leishmania and their role in host pathogenesis. Here we report the intracellular distribution of a novel L. donovani secretory serine protease in the flagellar pocket, as determined by immunogold labeling. Flow cytometry and confocal immunofluorescence analysis revealed that the expression of the protease diminishes sequentially from virulent to attenuated strains of this species and is also highly associated with the metacyclic stage of L. donovani promastigotes. The level of internalization of parasites treated with the anti-115-kDa antibody into host macrophages was significantly reduced from that of non-antibody-treated parasites, suggesting that this serine protease probably plays a role in the infection process. In vivo studies confirmed that this serine protease is a potential vaccine candidate. Altogether, the 115-kDa serine protease might play vital roles in L. donovani pathogenesis and hence could be recognized as a potential candidate for drug design.
蛋白酶已被发现在许多生物过程中发挥重要作用，包括利什曼病的发病机制。大多数寄生虫依靠其细胞内和细胞外的蛋白酶库在哺乳动物宿主细胞中侵袭和繁殖。然而，很少有研究涉及利什曼原虫中的丝氨酸蛋白酶及其在宿主发病机制中的作用。在此，我们报告了一种新型杜氏利什曼原虫分泌性丝氨酸蛋白酶在鞭毛袋中的细胞内分布，这是通过免疫金标记确定的。流式细胞术和共聚焦免疫荧光分析显示，该蛋白酶的表达在该物种的强毒株到弱毒株中依次降低，并且还与杜氏利什曼原虫前鞭毛体的循环后期阶段高度相关。用抗115 kDa抗体处理的寄生虫进入宿主巨噬细胞的内化水平比未用抗体处理的寄生虫显著降低，这表明这种丝氨酸蛋白酶可能在感染过程中起作用。体内研究证实，这种丝氨酸蛋白酶是一种潜在的疫苗候选物。总之，115 kDa丝氨酸蛋白酶可能在杜氏利什曼原虫的发病机制中发挥重要作用，因此可被视为药物设计的潜在候选物。
