Infectious Diseases Division, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
Infectious Diseases Division, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA
Infect Immun. 2019 Apr 23;87(5). doi: 10.1128/IAI.00784-18. Print 2019 Mar.
Despite the severity and global burden of infection, treatments are less than optimal, and there is no effective vaccine. Egress from host cells is a key process for the completion of the life cycle of apicomplexan parasites. For species, subtilisin-like serine protease (SUB1) is a key mediator of egress. For species, calcium-dependent protein kinases (CDPKs) are critical. In this study, we characterized SUB1 expression and evaluated its effect using an infection model. We found increased expression between 12 and 20 h after infection, prior to egress. We induced silencing of SUB1 (ΔSUB1) mRNA using SUB1 single-stranded antisense RNA coupled with human Argonaute 2. Silencing of SUB1 mRNA expression did not affect parasite viability, excystation, or invasion of target cells. However, knockdown led to a 95% decrease in the proportion of released merozoites ( < 0.0001). In contrast, silencing of CDPK5 had no effect on egress. Overall, our results indicate that SUB1 is a key mediator of egress and suggest that interruption of the life cycle at this stage may effectively inhibit the propagation of infection.
尽管 感染的严重性和全球负担很大，但治疗方法并不理想，也没有有效的疫苗。从宿主细胞逸出是完成顶复门寄生虫生命周期的关键过程。对于 物种，枯草杆菌蛋白酶样丝氨酸蛋白酶 (SUB1) 是逸出的关键介质。对于 物种，钙依赖性蛋白激酶 (CDPK) 是关键。在这项研究中，我们对 SUB1 的表达进行了表征，并使用感染模型评估了其作用。我们发现，在 感染后 12 至 20 小时之间，SUB1 的表达增加，在逸出之前。我们使用 SUB1 单链反义 RNA 与人 Argonaute 2 偶联来诱导 SUB1 (ΔSUB1) mRNA 的沉默。SUB1 mRNA 表达的沉默不影响寄生虫的活力、出囊或靶细胞的入侵。然而，敲低导致释放的裂殖子比例降低了 95%（<0.0001）。相比之下，CDPK5 的沉默对逸出没有影响。总体而言，我们的结果表明 SUB1 是 逸出的关键介质，并表明在此阶段中断生命周期可能有效抑制感染的传播。
