Gelanew Tesfaye, Lalle Marco, Hailu Asrat, Pozio Edoardo, Cacciò Simone M
Department of Microbiology, Immunology and Parasitology, Faculty of Medicine, Addis Ababa University, P.O. Box 9086, Addis Ababa, Ethiopia.
Acta Trop. 2007 May;102(2):92-9. doi: 10.1016/j.actatropica.2007.04.003. Epub 2007 Apr 8.
Giardia duodenalis, a flagellated protozoan, represents a common cause of gastroenteritis in Ethiopia, however very little information is available on the epidemiology and transmission routes of this pathogen, and a genetic characterization of the parasite has never been attempted in this country. The aim of this study was the genetic analysis of human isolates of G. duodenalis collected in different localities across the country, both from urban and rural areas. A fragment of the beta-giardin gene was amplified by nested PCR and analyzed by restriction and sequence analyses. Of the 59 isolates examined, 31 (52%) were typed as assemblage A and 13 (22%) as assemblage B. A strong correlation between the presence of symptoms and infection with assemblage B was observed. The remaining 15 (25%) isolates were typed as mixed infections by PCR-RFLP, specifically, A+F (in seven isolates) and A+B (in eight isolates). Sequencing of the A+F products confirmed the presence of assemblage F in three isolates, whereas the remaining four were identified as assemblage A. The detection of assemblage F, a cat-specific assemblage that to date has not been associated with human infections, was not able to be confirmed by the analysis of two commonly used markers (small subunit ribosomal RNA and triosephosphate isomerase). The analysis of the one isolate that was successfully amplified with the glutamate dehydrogenase primers unambiguously identified it as G. duodenalis, yet it was distinct from the established A and F sequences; thus the exact genetic identity of these isolates remains unclear.
十二指肠贾第虫是一种有鞭毛的原生动物，是埃塞俄比亚肠胃炎的常见病因。然而，关于这种病原体的流行病学和传播途径的信息非常少，该国从未尝试对该寄生虫进行基因特征分析。本研究的目的是对从该国不同地区（包括城市和农村）收集的人类十二指肠贾第虫分离株进行基因分析。通过巢式PCR扩增β-贾第素基因片段，并通过限制性分析和序列分析进行分析。在所检测的59个分离株中，31个（52%）被分型为A群，13个（22%）为B群。观察到症状的出现与B群感染之间存在强烈相关性。其余15个（25%）分离株通过PCR-RFLP分型为混合感染，具体为A+F（7个分离株）和A+B（8个分离株）。A+F产物的测序证实3个分离株中存在F群，而其余4个被鉴定为A群。F群是一种特定于猫的菌群，迄今为止尚未与人类感染相关联，通过分析两个常用标记（小亚基核糖体RNA和磷酸丙糖异构酶）无法确认其存在。用谷氨酸脱氢酶引物成功扩增的一个分离株的分析明确将其鉴定为十二指肠贾第虫，但它与已确定的A和F序列不同；因此，这些分离株的确切基因身份仍不清楚。
