Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Kuwait University, P.O. Box 31470, 90805, Sulaibikhat, Kuwait,
Parasitol Res. 2013 Dec;112(12):4043-51. doi: 10.1007/s00436-013-3595-9. Epub 2013 Sep 5.
Repeated incubation of Plasmodium falciparum culture in 0.015% saponin solution for a total of 35 min destroys most of the uninfected cells, leaving only the ring-infected erythrocytes (RIEs). Parasites concentrated by this method can subsequently complete the asexual cycle and infect other erythrocytes. It is possible that resistance to saponin is mediated by one or more of the numerous parasite proteins present in the host erythrocyte membrane. We have found that schizonts are as susceptible as uninfected erythrocytes to saponin, indicating that the protective protein is parasite stage specific. Studies with cultured parasites have shown that ring-infected erythrocyte surface antigen (RESA) strengthens host erythrocyte membrane and protects against destruction. Therefore, we hypothesize that RESA could be involved in resistance to saponin. Here, we have carried out PCR test on RESA gene, using three different primers. One of them showed that P. falciparum isolates collected directly from infected humans and cultured only for a few days, or not at all, have amplicon sizes ranging from 372 to 510 bp. However, the amplicon size changed to 873 bp when in vitro growth was continued for one or more weeks. This genetic transformation precedes acquisition of the ability to confer saponin resistance to RIEs.
重复孵育恶性疟原虫培养物在 0.015%皂素溶液中总共 35 分钟，可以破坏大部分未感染的细胞，只留下环状感染的红细胞（RIE）。通过这种方法浓缩的寄生虫随后可以完成无性周期并感染其他红细胞。对皂素的抗性可能是由存在于宿主红细胞膜中的许多寄生虫蛋白中的一种或多种介导的。我们发现裂殖体与未感染的红细胞一样容易受到皂素的影响，这表明保护蛋白是寄生虫阶段特异性的。对培养寄生虫的研究表明，环状感染红细胞表面抗原（RESA）增强了宿主红细胞膜并防止破坏。因此，我们假设 RESA 可能参与了对皂素的抗性。在这里，我们使用三种不同的引物对 RESA 基因进行了 PCR 测试。其中一种表明，直接从感染的人类中收集并仅培养几天或根本不培养的恶性疟原虫分离株的扩增子大小范围为 372 至 510bp。然而，当体外生长持续一周或更长时间时，扩增子大小变为 873bp。这种遗传转化先于获得赋予 RIE 对皂素抗性的能力。
