Franzen Caspar
Department of Internal Medicine I, University of Regensburg, 93042 Regensburg, Germany.
Folia Parasitol (Praha). 2005 May;52(1-2):36-40. doi: 10.14411/fp.2005.005.
Microsporidia are obligate intracellular eukaryotic parasites that utilize a unique mechanism to infect host cells. One of the main characteristics of all microsporidia is that they produce spores containing an extrusion apparatus that consists of a coiled polar tube ending in an anchoring disc at the apical part of the spore. With appropriate conditions inside a suitable host, the polar tube is discharged through the thin anterior end of the spore, thereby penetrating a new host cell for inoculating the infective sporoplasm into the new host cell. This method of invading new host cells is one of the most sophisticated infection mechanisms in biology and ensures that the microsporidia enter the host cell unrecognized and protected from the host defence reactions. Recent studies have shown that microsporidia gain access to host cells by phagocytosis as well. However, after phagocytosis, the special infection mechanism of the microsporidia is used to escape from the maturing phagosomes and to infect the cytoplasm of the cells. Gaining access to cells by endocytosis, and escaping destruction in the phago-/endo-/lysosome by egressing quickly from the phagocytic vacuole to multiply outside the lysosome, is a common phenomenon in biology that has been evolved several times during evolution. How this is put into execution by the microsporidia is an inimitable principle by which an obligate intracellular organism has managed this problem. The extrusion apparatus of the microsporidia has obviously ensured the success of this phylum during evolution, resulting in a group of obligate intracellular organisms, capable of infecting almost any type of host and cell.
微孢子虫是专性细胞内真核寄生虫，利用独特机制感染宿主细胞。所有微孢子虫的主要特征之一是它们产生含有挤压装置的孢子，该装置由一根盘绕的极管组成，极管在孢子顶端以锚定盘结束。在合适宿主内的适宜条件下，极管通过孢子前端的薄壁排出，从而穿透新的宿主细胞，将感染性孢子质接种到新宿主细胞中。这种侵入新宿主细胞的方法是生物学中最复杂的感染机制之一，确保微孢子虫进入宿主细胞时不被识别，并免受宿主防御反应的影响。最近的研究表明，微孢子虫也通过吞噬作用进入宿主细胞。然而，吞噬作用后，微孢子虫利用其特殊的感染机制从成熟的吞噬体中逃脱，并感染细胞的细胞质。通过内吞作用进入细胞，并通过迅速从吞噬泡中逸出以在溶酶体外部增殖，从而逃避吞噬/内吞/溶酶体中的破坏，这是生物学中的一种常见现象，在进化过程中已经多次出现。微孢子虫如何执行这一过程是一种独特的原理，专性细胞内生物通过该原理解决了这个问题。微孢子虫的挤压装置显然在进化过程中确保了该门的成功，产生了一组能够感染几乎任何类型宿主和细胞的专性细胞内生物。
