Cunningham Deirdre, Lawton Jennifer, Jarra William, Preiser Peter, Langhorne Jean
Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.
Mol Biochem Parasitol. 2010 Apr;170(2):65-73. doi: 10.1016/j.molbiopara.2009.12.010. Epub 2010 Jan 4.
Multigene families are present on the telomeric and sub-telomeric regions of most chromosomes of the malaria parasite, Plasmodium. The largest gene family identified so far is the Plasmodium interspersed repeat (pir) multigene gene family and is shared by Plasmodium vivax, and simian and rodent malaria species. Most pir genes share a similar structure across the different species; a short first exon, long second exon and a third exon encoding a trans-membrane domain, and some pir genes can be assigned to specific sub-families. Although pir genes can be differentially transcribed in different life cycle stages, suggesting different functions, there is no clear link between sub-family and transcription pattern. Some of the pir genes encode proteins expressed on or near the surface of infected erythrocytes, and therefore could be potential targets of the host's immune response, and involved in antigenic variation and immune evasion. Other functions such as signalling, trafficking and adhesion have been also postulated. The presence of pir in rodent models will allow the investigation of this gene family in vivo and thus their potential as vaccines or in other interventions in human P. vivax infections.
多基因家族存在于疟原虫（疟原虫属）大多数染色体的端粒和亚端粒区域。迄今为止鉴定出的最大基因家族是疟原虫散布重复序列（pir）多基因家族，间日疟原虫、猿猴疟原虫和啮齿动物疟原虫物种都有该家族。大多数pir基因在不同物种间具有相似结构：一个短的第一外显子、长的第二外显子和一个编码跨膜结构域的第三外显子，一些pir基因可归为特定的亚家族。尽管pir基因在不同生命周期阶段的转录存在差异，提示其功能不同，但亚家族与转录模式之间没有明确联系。一些pir基因编码在受感染红细胞表面或其附近表达的蛋白质，因此可能是宿主免疫反应的潜在靶点，并参与抗原变异和免疫逃避。也有人推测pir基因还具有信号传导、运输和黏附等其他功能。啮齿动物模型中pir基因的存在将有助于在体内研究这个基因家族，从而了解它们作为疫苗或用于人类间日疟原虫感染的其他干预措施的潜力。
