Lehrstuhl für Zell- und Entwicklungsbiologie, Biozentrum, Julius-Maximilians-Universität, Würzburg, Germany.
Lehrstuhl für Bioinformatik, Biozentrum, Julius-Maximilians-Universität, Würzburg, Germany.
Elife. 2021 Aug 6;10:e66028. doi: 10.7554/eLife.66028.
African trypanosomes cause sleeping sickness in humans and nagana in cattle. These unicellular parasites are transmitted by the bloodsucking tsetse fly. In the mammalian host's circulation, proliferating slender stage cells differentiate into cell cycle-arrested stumpy stage cells when they reach high population densities. This stage transition is thought to fulfil two main functions: first, it auto-regulates the parasite load in the host; second, the stumpy stage is regarded as the only stage capable of successful vector transmission. Here, we show that proliferating slender stage trypanosomes express the mRNA and protein of a known stumpy stage marker, complete the complex life cycle in the fly as successfully as the stumpy stage, and require only a single parasite for productive infection. These findings suggest a reassessment of the traditional view of the trypanosome life cycle. They may also provide a solution to a long-lasting paradox, namely the successful transmission of parasites in chronic infections, despite low parasitemia.
非洲锥虫会导致人类昏睡病和牛的那加那病。这些单细胞寄生虫通过吸血的采采蝇传播。在哺乳动物宿主的循环中，当增殖的纤细阶段细胞达到高种群密度时，它们会分化为细胞周期停滞的粗短阶段细胞。人们认为这种阶段转变满足两个主要功能：首先，它自动调节宿主中的寄生虫负荷；其次，粗短阶段被认为是唯一能够成功进行媒介传播的阶段。在这里，我们表明增殖的纤细阶段锥虫表达了已知的粗短阶段标记物的 mRNA 和蛋白质，在蝇中成功完成了完整的生命周期，并且只需要一个寄生虫就可以进行有性感染。这些发现表明需要重新评估锥虫生命周期的传统观点。它们也可能为一个长期存在的悖论提供解决方案，即在慢性感染中尽管寄生虫血症较低，但仍能成功传播寄生虫。
