School of Applied Sciences and Engineering, Monash University Gippsland Campus, Churchill 3842, Victoria, Australia.
Int J Parasitol. 2012 May 1;42(5):501-9. doi: 10.1016/j.ijpara.2012.04.004. Epub 2012 Apr 26.
Giardia duodenalis is a re-emerging protozoan parasite that causes diarrhoea in humans, significantly affecting the health of many people globally. To date, little is known about the genetic events underpinning the establishment of infection in host cells; however, the parasite's ventral disc, proteases and variable surface proteins (VSPs) are recognised as important pathogenic factors. In this study, representational difference analysis (RDA) was used to identify differentially expressed genes in four different Giardia isolates (WB, P-1, NF and GS/M) during the first 2h of in vitro interaction with the rat intestinal epithelial cell line, IEC-6. RDA showed that more than 40 genes were differentially expressed in each of the four Giardia isolates upon IEC-6 cells infection. Most of the up-regulated genes were common to the four isolates except for those encoding proteins possibly involved in immune evasion such as VSPs, high cysteine membrane proteins (HCMp), hypothetical proteins, and oxygen defence proteins (e.g., thioredoxin, peroxiredoxin 1). Differences in the expressed VSPs and HCMp may account for the variation in symptoms during giardiasis. Interestingly, the NF isolate solely expressed genes involved in encystation during interaction with IEC-6 (e.g., glucosamine 6-phosphate isomerase, dynamin, acid sphingomyelinase-like phosphodiesterase) suggesting that encystation signals could be different for this isolate. Common to the four isolates, transcripts for genes involved in glycolysis (e.g., glucose-6-phosphate dehydrogenase, fructose bisphosphate aldolase, enolase), attachment (γ and α1 giardins) and cysteine proteases were frequently detected. Genes involved in transcription, translation, signalling and cell cycle control were also up-regulated. This study shows that the RDA technique has selectively isolated genes involved in host-parasite interactions and complements previous microarray data. Some of the detected genes are also discussed as potential virulence factors and treatment targets in giardiasis.
十二指肠贾第鞭毛虫是一种重新出现的原生动物寄生虫，会导致人类腹泻，严重影响全球许多人的健康。迄今为止，人们对宿主细胞感染的遗传事件知之甚少；然而，寄生虫的腹盘、蛋白酶和可变表面蛋白（VSP）被认为是重要的致病因素。在这项研究中，代表性差异分析（RDA）用于鉴定在与大鼠肠上皮细胞系 IEC-6 体外相互作用的前 2 小时内，四种不同的贾第鞭毛虫分离株（WB、P-1、NF 和 GS/M）中差异表达的基因。RDA 显示，在 IEC-6 细胞感染后，四种贾第鞭毛虫分离株中的 40 多个基因表达差异。上调的基因大多数在四个分离株中是共同的，除了那些编码可能参与免疫逃避的蛋白质的基因，如 VSP、高半胱氨酸膜蛋白（HCMp）、假设蛋白和氧防御蛋白（如硫氧还蛋白、过氧化物酶 1）。表达的 VSP 和 HCMp 的差异可能导致贾第虫病期间症状的变化。有趣的是，NF 分离株在与 IEC-6 相互作用期间仅表达与囊形成相关的基因（如葡萄糖-6-磷酸异构酶、动力蛋白、酸性神经鞘磷脂酶样磷酸二酯酶），这表明该分离株的囊形成信号可能不同。四个分离株共有的是参与糖酵解的基因（如葡萄糖-6-磷酸脱氢酶、果糖二磷酸醛缩酶、烯醇酶）、附着（γ和α1 贾第素）和半胱氨酸蛋白酶的转录本。参与转录、翻译、信号和细胞周期控制的基因也被上调。本研究表明，RDA 技术已选择性地分离了参与宿主-寄生虫相互作用的基因，并补充了以前的微阵列数据。一些检测到的基因也被讨论为贾第虫病的潜在毒力因子和治疗靶点。
