Bastos Armanda D S, Mohammed Osama B, Bennett Nigel C, Petevinos Charalambos, Alagaili Abdulaziz N
Department of Zoology & Entomology, University of Pretoria, Private Bag 20, Hatfield 0028, Pretoria, South Africa.
KSU Mammals Research Chair, Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
Vet Microbiol. 2015 Sep 30;179(3-4):310-4. doi: 10.1016/j.vetmic.2015.06.001. Epub 2015 Jun 10.
Serological surveys have confirmed Anaplasma marginale and Anaplasma phagocytophilum infections in dromedary camels, but molecular surveys and genetic characterisation of camel-associated Anaplasma species are lacking. In this study, we detected tick-borne Anaplasmataceae in 30 of 100 (30%) healthy dromedary camels screened using a combined 16S rRNA-groEL PCR-sequencing approach. Nucleotide sequencing confirmed Anaplasmataceae genome presence in 28 of the 33 16S rRNA PCR-positive samples, with two additional positive samples, for which 16S rRNA sequence data were ambiguous, being identified by groEL gene characterisation. Phylogenetic analyses of a 1289 nt segment of the 16S rRNA gene confirmed the presence of a unique Ehrlichia lineage and a discrete Anaplasma lineage, comprising three variants, occurring at an overall prevalence of 4% and 26%, respectively. Genetic characterisation of an aligned 559 nt groEL gene region revealed the camel-associated Anaplasma and Ehrlichia lineages to be novel and most closely related to Anaplasma platys and Ehrlichia canis. Based on the confirmed monophyly, minimum pairwise genetic distances between each novel lineage and its closest sister taxon, and the inability to isolate the bacteria, we propose that Candidatus status be assigned to each. This first genetic characterisation of Anaplasmataceae from naturally infected, asymptomatic dromedary camels in Saudi Arabia confirms the presence of two novel lineages that are phylogenetically linked to two pathogenic canid species of increasing zoonotic concern.
血清学调查已证实单峰骆驼感染了边缘无形体和嗜吞噬细胞无形体，但缺乏对与骆驼相关的无形体物种的分子调查和基因特征分析。在本研究中，我们使用16S rRNA-groEL PCR测序联合方法，在100头接受筛查的健康单峰骆驼中的30头（30%）中检测到了蜱传无形体科细菌。核苷酸测序证实，在33个16S rRNA PCR阳性样本中的28个样本中存在无形体科基因组，另外两个阳性样本的16S rRNA序列数据不明确，通过groEL基因特征分析得以鉴定。对16S rRNA基因1289 nt片段的系统发育分析证实存在一个独特的埃立克体谱系和一个离散的无形体谱系，分别包含三个变体，总体患病率分别为4%和26%。对559 nt的groEL基因区域进行比对后的基因特征分析表明，与骆驼相关的无形体和埃立克体谱系是新的，并且与血小板无形体和犬埃立克体关系最为密切。基于已确认的单系性、每个新谱系与其最接近的姐妹分类群之间的最小成对遗传距离以及无法分离出细菌，我们建议将每个谱系指定为候选分类单元。对沙特阿拉伯自然感染、无症状单峰骆驼中无形体科的首次基因特征分析证实存在两个新谱系，它们在系统发育上与两种日益引起人畜共患病关注的致病性犬科物种相关。
