Beĭer T V, Svezhova N V, Radchenko A I, Sidorenko N V
Institute of Cytology RAS, 194064, St. Petersburg.
Tsitologiia. 2003;45(4):339-56.
Data on parasitophorous vacuole (PV) formation in host cells (HC) harbouring different intracellular protozoan parasites have been reviewed and critically analysed, with special reference to the main representatives of the Coccidia. The vacuole membrane (PVM) is the interface between host and parasite, playing a role in nutrient acquisition by the parasite from the HC. The PV phenomenon is regarded as a generalized HC response to the introduction of alien bodies (microorganisms), which eventually reflects the evolutionary established host-parasite relationships at cellular, subcellular and molecular levels. Special attention has been paid to the existing morpho-functional diversity of the PVs within the same genera and species of parasites, and even at different stages of the parasite life cycle. The PVM is generally considered to derive from the HC plasmalemma, whose biochemical composition undergoes significant changes as the intravacuolar parasite grows. The original HC proteins are selectively excluded from the PVM, while those of the parasite are incorporated. As the result, the changed PVM becomes not fusigenic for HC lysosomes. For Toxoplasma gondii and other cyst-forming coccidia (Isospora, Sarcocystis), a definite correlation has been noticed between the extent of rhoptry and dense granule secrets released by a zoite during HC internalization, on the one hand, and the pattern of the PV that forms, on the other one. In T. gondii, tachyzoites, known to discharge abundant secrets, commonly force the development of PVs limited with a single unit membrane and equipped with a tubulovesicular network in the lumen. Unlike, bradyzoites known to be deficient in secretory materials trigger the formation of PVs with a three-membrane lining composed of the changed invaginated plasmalemma in addition to two membranes of endoplasmic reticulum. The two different types of PV harbour, respectively, exoenteric and enteric stages of T. gondii, the latter being confined to the cat intestine only. Unlike, all endogenous stages of the classic intestinal coccidia (Eimeria spp.) develop within PVs limited with a single membrane, with some invaginations extending into the PV lumen. Unusual PV patterns are characteristic of the extracytoplasmic eimerian coccidia (Cryptosporidium, Epieimeria) and adeleid haemogreagarines (Karyolysus). In cyst-forming coccidia, the PVM is actively involved in tissue cyst wall formation, thus protecting the encysted parasites from recognition by the host immune system. All this strongly suggests that the PV is far from being an indifferent membraneous vesicle containing a parasite, but represents a metabolically active compartment in infected cells. Since all the coccidia are obligate intracellular parasites, the mode of their intimate interaction with the HC, largely accomplished via the PV and its membrane, is vital for their survival as biological species.
关于含有不同细胞内原生动物寄生虫的宿主细胞（HC）中寄生泡（PV）形成的数据已被综述并进行了批判性分析，特别参考了球虫的主要代表。泡膜（PVM）是宿主与寄生虫之间的界面，在寄生虫从HC获取营养方面发挥作用。PV现象被视为宿主细胞对异物（微生物）引入的一种普遍反应，最终反映了在细胞、亚细胞和分子水平上进化形成的宿主 - 寄生虫关系。特别关注了同一属和种的寄生虫内，甚至在寄生虫生命周期的不同阶段，PV现有的形态 - 功能多样性。PVM通常被认为源自HC质膜，随着泡内寄生虫的生长，其生化组成会发生显著变化。原始的HC蛋白被选择性地排除在PVM之外，而寄生虫的蛋白则被整合进去。结果，改变后的PVM对HC溶酶体不再具有融合性。对于刚地弓形虫和其他形成包囊的球虫（等孢球虫、肉孢子虫），一方面，在HC内化过程中速殖子释放的棒状体和致密颗粒分泌物的程度与另一方面形成的PV模式之间已发现明确的相关性。在刚地弓形虫中，已知释放大量分泌物的速殖子通常促使形成由单个单位膜限制且腔内配备有管状泡网络的PV。与之不同的是，已知分泌物质缺乏的缓殖子引发形成具有三层膜内衬的PV，除了内质网的两层膜外，还包括改变后的内陷质膜。这两种不同类型的PV分别容纳刚地弓形虫的肠外和肠内阶段，后者仅局限于猫的肠道。与之不同的是，经典肠道球虫（艾美耳属）的所有内源性阶段都在由单层膜限制的PV内发育，一些内陷延伸到PV腔内。异常的PV模式是胞外艾美耳球虫（隐孢子虫、艾美耳隐孢子虫）和阿德勒血孢子虫（核虫）的特征。在形成包囊的球虫中，PVM积极参与组织包囊壁的形成，从而保护包囊内的寄生虫不被宿主免疫系统识别。所有这些都强烈表明，PV远非一个容纳寄生虫的无活性膜泡，而是感染细胞中一个代谢活跃的区室。由于所有球虫都是专性细胞内寄生虫，它们与HC密切相互作用的方式，很大程度上是通过PV及其膜来完成的，这对它们作为生物物种的生存至关重要。
