New insights into the systematics of the afrotropical Amblyomma marmoreum complex (Acari: Ixodidae) and the genome of a novel Rickettsia africae strain using morphological and metagenomic approaches
Andrea P. Cotes-Perdomo , Alberto Sánchez-Vialas , Richard Thomas , Andrew Jenkins , Juan E. Uribe
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引用次数: 0
Abstract
The Amblyomma marmoreum complex includes afrotropical species, such as Amblyomma sparsum, a three-host tick that parasitizes reptiles, birds, and mammals, and is a recognized vector of Ehrlichia ruminantium. However, the lack of morphological, genetic and ecological data on A. sparsum has caused considerable confusion in its identification. In this study, we used microscopy and metagenomic approaches to analyze A. sparsum ticks collected from a puff adder snake (Bitis arietans) in southwest Senegal (an endemic rickettsioses area) in order to supplement previous morphological descriptions, provide novel genomic data for the A. marmoreum complex, and describe the genome of a novel spotted fever group Rickettsia strain. Based on stereoscope and scanning electron microscopy (SEM) morphological evaluations, we provide high-quality images and new insights about punctation and enameling in the adult male of A. sparsum to facilitate identification for future studies. The metagenomic approach allowed us assembly the complete mitochondrial genome of A. sparsum, as well as the nearly entire chromosome and complete plasmid sequences of a novel Rickettsia africae strain. Phylogenomic analyses demonstrated a close relationship between A. sparsum and Amblyomma nuttalli for the first time and confirmed the position of A. sparsum within the A. marmoreum complex. Our results provide new insights into the systematics of A. sparsum and A. marmoreum complex, as well as the genetic diversity of R. africae in the Afrotropical region. Future studies should consider the possibility that A. sparsum may be a vector for R. africae.
Amblyomma marmoreum复合体包括非洲热带物种,如Amblyomma sparsum,它是一种三寄主蜱,寄生于爬行动物、鸟类和哺乳动物,是公认的反刍埃希氏菌病媒。然而,由于缺乏关于A. sparsum的形态学、遗传学和生态学数据,导致其鉴定工作相当混乱。在这项研究中,我们使用显微镜和元基因组学方法分析了从塞内加尔西南部(立克次体病流行区)的一种浮萍蛇(Bitis arietans)身上采集的A. sparsum蜱,以补充之前的形态学描述,为A. marmoreum复合体提供新的基因组数据,并描述了一种新型斑疹热群立克次体菌株的基因组。基于体视镜和扫描电子显微镜(SEM)的形态学评估,我们提供了高质量的图像,并对A. sparsum雄性成虫的点状和珐琅质有了新的认识,为今后的研究提供了鉴定依据。元基因组学方法使我们能够组装出 A. sparsum 的完整线粒体基因组,以及一株新型非洲立克次体的几乎全部染色体和完整质粒序列。系统发生组分析首次证明了A. sparsum与Amblyomma nuttalli之间的密切关系,并确认了A. sparsum在A. marmoreum复合体中的位置。我们的研究结果为 A. sparsum 和 A. marmoreum 复合体的系统学以及非洲热带地区 R. africae 的遗传多样性提供了新的见解。未来的研究应考虑到 A. sparsum 可能是 R. africae 的病媒这一可能性。
期刊介绍:
Ticks and Tick-borne Diseases is an international, peer-reviewed scientific journal. It publishes original research papers, short communications, state-of-the-art mini-reviews, letters to the editor, clinical-case studies, announcements of pertinent international meetings, and editorials.
The journal covers a broad spectrum and brings together various disciplines, for example, zoology, microbiology, molecular biology, genetics, mathematical modelling, veterinary and human medicine. Multidisciplinary approaches and the use of conventional and novel methods/methodologies (in the field and in the laboratory) are crucial for deeper understanding of the natural processes and human behaviour/activities that result in human or animal diseases and in economic effects of ticks and tick-borne pathogens. Such understanding is essential for management of tick populations and tick-borne diseases in an effective and environmentally acceptable manner.