Sección Parasitología, Instituto de Salud Pública de Chile, Av. Marathon 1000, Ñuñoa, CP 7780050, Santiago, Chile.
Departamento de Parasitología, Instituto de Biotecnología, Grupo de Bioquímica y Parasitología Molecular, Universidad de Granada, Campus Universitario Fuentenueva, 18071, Granada, Spain.
Parasit Vectors. 2019 Jan 25;12(1):58. doi: 10.1186/s13071-019-3302-5.
Acanthamoeba spp. are the causative agents of a severe keratitis occurring mainly in contact lens wearers. The genus comprises more than 24 species that are currently divided into 20 different genotypes (T1-T20) according to sequence variations in the 18S rRNA gene. The objective of this study was to identify the genotypes and sub-genotypes of Acanthamoeba isolates collected at the Parasitology Laboratory of the Public Health Institute of Chile, the only laboratory in the country where Acanthamoeba screening is performed. This is the first report of genotypic identification of clinical isolates of Acanthamoeba in Chile and one of the few in South America.
In this study, 114 Acanthamoeba isolates from 76 Acanthamoeba keratitis patients, obtained between 2005-2016, were genotyped. T4 was the predominant genotype; T2 and T11 genotypes, which are scarcely reported worldwide, were also identified in Chilean patients (one and two patients, respectively). This is the first report of T2 and T11 genotypes isolated from Acanthamoeba keratitis patients in South America. It is also the first report of the T2 genotype circulating in this continent. Analysis of the diagnostic fragment 3 region of the 18S rRNA gene showed 24 T4 variants, with a predominance of the sub-genotype T4/A, followed by T4/B, T4/G, T4/C and T4/D. Bayesian analysis revealed three groups among the T4 variants: two well supported groups that included 12 and 7 sub-genotypes, respectively, and a weakly supported group that included 5 sub-genotypes. Most of the predominant T4 sub-genotypes belonged to the same group, which included 71.3% of the patients, while some minority variants lied mainly in the other two clusters.
T2, T4 and T11 genotypes were predominantly isolated from the Acanthamoeba keratitis patients in Chile. Chilean predominant T4 sub-genotypes, which have also been reported worldwide, formed a separate cluster of the minority T4 variants. This study provides useful information about the predominant genotypes and subgenotypes that would be useful in selecting suitable strains to develop immunological and/or molecular diagnostic assays in Chile.
棘阿米巴属是主要发生在隐形眼镜佩戴者中的一种严重角膜炎的病原体。该属包括 24 多种种，根据 18S rRNA 基因序列的变化，目前分为 20 个不同的基因型（T1-T20）。本研究的目的是鉴定在智利公共卫生研究所寄生虫学实验室收集的棘阿米巴分离株的基因型和亚型，该实验室是该国唯一进行棘阿米巴筛查的实验室。这是智利首次报道临床分离棘阿米巴的基因分型，也是南美洲为数不多的报道之一。
在这项研究中，对 76 名棘阿米巴角膜炎患者（2005-2016 年期间获得）的 114 株棘阿米巴分离株进行了基因分型。T4 是主要的基因型；在智利患者中也发现了在世界范围内很少报道的 T2 和 T11 基因型（分别为一名和两名患者）。这是首次在南美洲从棘阿米巴角膜炎患者中分离出 T2 和 T11 基因型的报道。也是首次报道 T2 基因型在该大陆流行。对 18S rRNA 基因的诊断片段 3 区域的分析显示，T4 有 24 种变体，以 T4/A 亚基因型为主，其次是 T4/B、T4/G、T4/C 和 T4/D。贝叶斯分析显示，T4 变体分为三组：两组支持度较高的组，分别包含 12 和 7 个亚基因型，以及一组支持度较低的组，包含 5 个亚基因型。主要 T4 亚基因型的大多数属于同一组，包括 71.3%的患者，而一些少数变体主要位于另外两个聚类中。
T2、T4 和 T11 基因型主要从智利的棘阿米巴角膜炎患者中分离出来。智利主要的 T4 亚基因型也在世界范围内报道过，形成了一个独立的少数 T4 变体集群。本研究提供了有关主要基因型和亚基因型的有用信息，这对于在智利选择合适的菌株来开发免疫和/或分子诊断检测将非常有用。
