Silvester Eleanor, McWilliam Kirsty R, Matthews Keith R
Institute for Immunology and Infection Research, Centre for Immunity, Infection and Evolution, School of Biological Sciences, King's Buildings, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
Pathogens. 2017 Jun 28;6(3):29. doi: 10.3390/pathogens6030029.
African trypanosomes cause devastating disease in sub-Saharan Africa in humans and livestock. The parasite lives extracellularly within the bloodstream of mammalian hosts and is transmitted by blood-feeding tsetse flies. In the blood, trypanosomes exhibit two developmental forms: the slender form and the stumpy form. The slender form proliferates in the bloodstream, establishes the parasite numbers and avoids host immunity through antigenic variation. The stumpy form, in contrast, is non-proliferative and is adapted for transmission. Here, we overview the features of slender and stumpy form parasites in terms of their cytological and molecular characteristics and discuss how these contribute to their distinct biological functions. Thereafter, we describe the technical developments that have enabled recent discoveries that uncover how the slender to stumpy transition is enacted in molecular terms. Finally, we highlight new understanding of how control of the balance between slender and stumpy form parasites interfaces with other components of the infection dynamic of trypanosomes in their mammalian hosts. This interplay between the host environment and the parasite's developmental biology may expose new vulnerabilities to therapeutic attack or reveal where drug control may be thwarted by the biological complexity of the parasite's lifestyle.
非洲锥虫在撒哈拉以南非洲地区给人类和牲畜造成毁灭性疾病。这种寄生虫在哺乳动物宿主的血液中营细胞外寄生生活，并由吸食血液的采采蝇传播。在血液中，锥虫呈现两种发育形态：细长型和粗短型。细长型在血液中增殖，确定寄生虫数量，并通过抗原变异逃避宿主免疫。相比之下，粗短型不增殖，适合传播。在这里，我们从细胞学和分子特征方面概述细长型和粗短型寄生虫的特点，并讨论这些特点如何促成它们独特的生物学功能。此后，我们描述了一些技术进展，这些进展促成了最近的发现，揭示了从分子层面上细长型向粗短型转变是如何发生的。最后，我们强调了对细长型和粗短型寄生虫之间平衡的控制如何与锥虫在其哺乳动物宿主中的感染动态的其他组成部分相互作用的新认识。宿主环境与寄生虫发育生物学之间的这种相互作用可能会暴露出新的治疗靶点，或者揭示出寄生虫复杂生活方式的生物学特性可能会阻碍药物控制的地方。
