Lerksuthirat Tassanee, Lohnoo Tassanee, Inkomlue Ruchuros, Rujirawat Thidarat, Yingyong Wanta, Khositnithikul Rommanee, Phaonakrop Narumon, Roytrakul Sittiruk, Sullivan Thomas D, Krajaejun Theerapong
Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand.
Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
PLoS One. 2015 Mar 20;10(3):e0118547. doi: 10.1371/journal.pone.0118547. eCollection 2015.
Pythium insidiosum is a unique oomycete that can infect humans and animals. Patients with a P. insidiosum infection (pythiosis) have high rates of morbidity and mortality. The pathogen resists conventional antifungal drugs. Information on the biology and pathogenesis of P. insidiosum is limited. Many pathogens secrete proteins, known as effectors, which can affect the host response and promote the infection process. Elicitins are secretory proteins and are found only in the oomycetes, primarily in Phytophthora and Pythium species. In plant-pathogenic oomycetes, elicitins function as pathogen-associated molecular pattern molecules, sterol carriers, and plant defense stimulators. Recently, we reported a number of elicitin-encoding genes from the P. insidiosum transcriptome. The function of elicitins during human infections is unknown. One of the P. insidiosum elicitin-encoding genes, ELI025, is highly expressed and up-regulated at body temperature. This study aims to characterize the biochemical, immunological, and genetic properties of the elicitin protein, ELI025. A 12.4-kDa recombinant ELI025 protein (rELI025) was expressed in Escherichia coli. Rabbit anti-rELI025 antibodies reacted strongly with the native ELI025 in P. insidiosum's culture medium. The detected ELI025 had two isoforms: glycosylated and non-glycosylated. ELI025 was not immunoreactive with sera from pythiosis patients. The region near the transcriptional start site of ELI025 contained conserved oomycete core promoter elements. In conclusion, ELI025 is a small, abundant, secreted glycoprotein that evades host antibody responses. ELI025 is a promising candidate for development of diagnostic and therapeutic targets for pythiosis.
毁灭腐霉是一种独特的卵菌，可感染人类和动物。感染毁灭腐霉（腐霉病）的患者发病率和死亡率很高。该病原体对传统抗真菌药物具有抗性。关于毁灭腐霉的生物学和发病机制的信息有限。许多病原体分泌称为效应子的蛋白质，这些蛋白质可影响宿主反应并促进感染过程。激发素是分泌蛋白，仅在卵菌中发现，主要存在于疫霉属和腐霉属物种中。在植物致病卵菌中，激发素作为病原体相关分子模式分子、甾醇载体和植物防御刺激剂发挥作用。最近，我们报道了来自毁灭腐霉转录组的一些激发素编码基因。激发素在人类感染期间的功能尚不清楚。毁灭腐霉激发素编码基因之一ELI025在体温下高度表达且上调。本研究旨在表征激发素蛋白ELI025的生化、免疫和遗传特性。一种12.4 kDa的重组ELI025蛋白（rELI025）在大肠杆菌中表达。兔抗rELI025抗体与毁灭腐霉培养基中的天然ELI025强烈反应。检测到的ELI025有两种异构体：糖基化和非糖基化。ELI025与腐霉病患者的血清无免疫反应。ELI025转录起始位点附近的区域包含保守的卵菌核心启动子元件。总之，ELI025是一种小的、丰富的、分泌型糖蛋白，可逃避宿主抗体反应。ELI025是开发腐霉病诊断和治疗靶点的有希望的候选物。
