Department of Infectious Disease Modelling and Epidemiology, Norwegian Institute of Public Health (FHI), Oslo, Norway.
Faculty of Veterinary Medicine, Department Food Safety and Infection Biology, The Norwegian University of Life Sciences (NMBU), Oslo, Norway.
Zoonoses Public Health. 2018 Sep;65(6):637-647. doi: 10.1111/zph.12470. Epub 2018 Apr 14.
Giardia duodenalis colonizes the gastrointestinal tract of a wide range of hosts, including humans and other primates. It is grouped into eight different Assemblages and, beyond that, into a number of sub-Assemblages, defined ad hoc on the basis of genetic differences; these various groups are often considered to be associated with a specific restricted host range. The aim of this study was to use publicly available genotyping data to investigate the relatedness of human and non-human primate (NHP) Giardia isolates in order to evaluate the usefulness of current taxonomic classification and to assess whether there is potential for zoonotic transmission between humans and NHP. Our final data set consisted of sequence data from 165 isolates, 111 from NHP and 54 from humans. Assemblages were well defined, but sub-Assemblages across Assemblage B were not resolved. Although sub-Assemblages AI and AII were resolved, the terms were not found to capture any useful molecular or host/deme properties. In the phylogenetic tree, NHP isolates were scattered among human isolates across Assemblages A and B, and were even found in Assemblage E. We conclude that there does not appear to be significant molecular distinction between human and NHP Giardia isolates across these four molecular markers. Thus, on the basis of these markers, we cannot exclude a risk for zoonotic and anthropozoonotic transmission of Assemblages A and B isolates, irrespective of sub-Assemblage classification. We further evaluated the relative merit of the four genes used in genotyping studies. The tpi, gdh and bg genes gave relatively congruent tree topologies, but the SSU gene did not resolve Assemblages according to the current classification. Future genotyping efforts should aim for multilocus or whole-genome approaches and, in particular, use of the SSU gene as the sole marker should be avoided when possible.
贾第虫寄生在包括人类和其他灵长类动物在内的广泛宿主的胃肠道中。它分为八个不同的集合体，此外，还分为许多亚集合体，这些亚集合体是根据遗传差异专门定义的；这些不同的群体通常被认为与特定的有限宿主范围有关。本研究旨在利用公开的基因分型数据来研究人类和非人类灵长类动物（NHP）贾第虫分离株的亲缘关系，以评估当前分类的有用性，并评估人类和 NHP 之间是否存在人畜共患传播的潜力。我们最终的数据集中包含了来自 165 个分离株的序列数据，其中 111 个来自 NHP，54 个来自人类。集合体定义明确，但 B 集合体中的亚集合体没有得到解决。虽然 A1 和 A2 亚集合体得到了解决，但这些术语并没有发现任何有用的分子或宿主/种群特性。在系统发育树中，NHP 分离株散布在 A 和 B 集合体的人类分离株中，甚至在 E 集合体中也发现了它们。我们的结论是，在这四个分子标记中，人类和 NHP 贾第虫分离株之间似乎没有明显的分子差异。因此，根据这些标记，我们不能排除 A 和 B 集合体分离株发生人畜共患和人兽共患传播的风险，而不论亚集合体的分类如何。我们进一步评估了用于基因分型研究的四个基因的相对优势。tpi、gdh 和 bg 基因给出了相对一致的系统发育树拓扑结构，但 SSU 基因没有按照当前的分类来解决集合体。未来的基因分型工作应针对多基因或全基因组方法，特别是在可能的情况下，应避免仅使用 SSU 基因作为唯一标记。
