Department of Parasitology, Mycology and Environmental Microbiology, Swedish Institute for Infectious Disease Control, Solna, Sweden.
Vet Parasitol. 2010 Mar 25;168(3-4):231-9. doi: 10.1016/j.vetpar.2009.11.003. Epub 2009 Nov 13.
Giardia intestinalis is a protozoan parasite that consists of seven genetically distinct assemblages (A to G). Assemblage A and B parasites have been detected in a wide range of animals including humans, while the other assemblages (C to G) appear to have a narrower host range. However, the knowledge about zoonotic transmission of G. intestinalis is limited. To address this question, 114 Giardia isolates from various animals in Sweden including pets, livestock, wildlife and captive non-human primates were investigated by a sequence-based analysis of three genes (beta-giardin, glutamate dehydrogenase and triose phosphate isomerase). Assemblage A infections were detected in nine ruminants, five cats and one dog, while three sheep were infected with both assemblages A and E. Multilocus genotypes (MLGs) were defined for assemblage A, and three of these MLGs have previously been detected in Giardia isolates from humans. The newly described sub-assemblage AIII, until now reported mainly in wild hoofed animals, was found in one cat isolate. Assemblage B occurred in three monkeys, one guinea pig and one rabbit. The rabbit isolate exhibited sequences at all three loci previously detected in human isolates. The non-zoonotic assemblages C, D, E, F or G were found in the remaining 83 G. intestinalis isolates, which were successfully amplified and genotyped, generating a wide variety of both novel and known sub-genotypes. Double peaks in chromatograms were seen in assemblage B, C, D and E isolates but were never observed in assemblage A, F and G isolates, which can reflect differences in allelic sequence divergence. No evidence of genetic exchange between assemblages was detected. The study shows that multilocus genotyping of G. intestinalis is a highly discriminatory and useful tool in the determination of zoonotic sub-groups within assemblage A, but less valuable for subtyping assemblages B, C, D and E due to the high frequency of double peaks in the chromatograms. The obtained data also suggest that zoonotic transmission of assemblages A and B might occur to a limited extent in Sweden.
肠道贾第虫是一种原生动物寄生虫，由七个具有不同遗传特征的集合体（A 到 G）组成。已经在包括人类在内的各种动物中检测到集合体 A 和 B 寄生虫，而其他集合体（C 到 G）似乎宿主范围较窄。然而，关于肠道贾第虫的人畜共患病传播的知识是有限的。为了解决这个问题，对来自瑞典的各种动物（包括宠物、家畜、野生动物和圈养非人类灵长类动物）的 114 个贾第虫分离株进行了基于序列的三个基因（β-微管蛋白、谷氨酸脱氢酶和磷酸丙糖异构酶）分析。在 9 只反刍动物、5 只猫和 1 只狗中检测到集合体 A 感染，而 3 只绵羊同时感染了集合体 A 和 E。确定了集合体 A 的多基因座基因型（MLG），其中 3 个 MLG 之前在人类贾第虫分离株中检测到。直到现在，主要在野生有蹄动物中报道的新描述的亚集合体 AIII 在 1 只猫分离株中发现。集合体 B 出现在 3 只猴子、1 只豚鼠和 1 只兔子中。兔分离株在所有三个基因座上均表现出先前在人类分离株中检测到的序列。在其余 83 个肠道贾第虫分离株中发现了非人畜共患病的集合体 C、D、E、F 或 G，这些分离株均成功扩增并进行了基因分型，产生了广泛的新型和已知亚基因型。在集合体 B、C、D 和 E 分离株的色谱图中观察到双峰，但在集合体 A、F 和 G 分离株中从未观察到双峰，这可能反映了等位基因序列差异。未检测到集合体之间的遗传交换证据。研究表明，肠道贾第虫的多位点基因分型是确定集合体 A 中人畜共患病亚群的高度区分性和有用工具，但由于色谱图中双峰的高频出现，对集合体 B、C、D 和 E 的亚型分型价值不大。获得的数据还表明，在瑞典，集合体 A 和 B 的人畜共患病传播可能在一定程度上发生。
