Vernick K D, Fujioka H, Seeley D C, Tandler B, Aikawa M, Miller L H
Molecular Entomology Section, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA.
Exp Parasitol. 1995 Jun;80(4):583-95. doi: 10.1006/expr.1995.1074.
We have identified a mechanism for refractoriness to a bird malaria, Plasmodium gallinaceum, in the African vector of human malaria, Anopheles gambiae. Oocysts fail to develop in the refractory mosquitoes as a result of ookinete death which occurs within 27 hr of midgut invasion. Ultrastructural studies showed that parasite death occurs while the ookinete lies free in the midgut epithelial cell cytosol, usually surrounded by an organelle-free zone that consists of finely fibrillar material. The mechanism of parasite killing does not involve a previously described refractory mechanism of parasite encapsulation. We selected genetic lines which are refractory and susceptible to midgut infection. Genetic crossing of the lines suggests that the refractory trait is inherited as a single dominant genetic locus. Other loci probably influence oocyst number in susceptible mosquitoes. Intracellular ookinete killing appears to involve a previously unrecognized host defense mechanism against malaria parasites that involves direct destruction of the invading organism.
我们已经在人类疟疾的非洲传播媒介冈比亚按蚊中，确定了一种对禽类疟疾——鸡疟原虫产生抗性的机制。在抗性蚊子中，由于子孢子在中肠入侵后27小时内死亡，卵囊无法发育。超微结构研究表明，当子孢子游离于中肠上皮细胞胞质溶胶中时，寄生虫就会死亡，其周围通常有一个无细胞器区，该区域由细纤维状物质组成。寄生虫杀灭机制并不涉及先前描述的寄生虫包囊抗性机制。我们选择了对中肠感染具有抗性和易感性的遗传品系。品系间的遗传杂交表明，抗性性状作为一个单一的显性遗传位点遗传。其他位点可能影响易感蚊子中卵囊的数量。细胞内子孢子杀灭似乎涉及一种以前未被认识的宿主针对疟原虫的防御机制，该机制涉及对入侵生物体的直接破坏。
