Laboratório de Epidemiologia e Sistemática Molecular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.
Centro/Norte, Escritório Técnico Regional - Fundação Oswaldo Cruz, Piauí, Rua Magalhães Filho, 519, Teresina, Piauí, Brazil.
Parasit Vectors. 2021 Mar 17;14(1):160. doi: 10.1186/s13071-021-04672-y.
Entamoeba species harbored by humans have different degrees of pathogenicity. The present study explores the intra- and interspecific diversity, phylogenetic relationships, prevalence and distribution of tetra- and octonucleated cyst-producing Entamoeba in different Brazilian regions.
Cross-sectional studies were performed to collect fecal samples (n = 1728) and sociodemographic data in communities located in four Brazilian biomes: Atlantic Forest, Caatinga, Cerrado, and Amazon. Fecal samples were subjected to molecular analysis by partial small subunit ribosomal DNA sequencing (SSU rDNA) and phylogenetic analysis.
Light microscopy analysis revealed that tetranucleated cysts were found in all the studied biomes. The highest positivity rates were observed in the age group 6-10 years (23.21%). For octonucleated cysts, positivity rates ranged from 1 to 55.1%. Sixty SSU rDNA Entamoeba sequences were obtained, and four different species were identified: the octonucleated E. coli, and the tetranucleated E. histolytica, E. dispar, and E. hartmanni. Novel haplotypes (n = 32) were characterized; however, new ribosomal lineages were not identified. The Entamoeba coli ST1 subtype predominated in Atlantic Forest and Caatinga, and the ST2 subtype was predominant in the Amazon biome. E. histolytica was detected only in the Amazon biome. In phylogenetic trees, sequences were grouped in two groups, the first containing uni- and tetranucleated and the second containing uni- and octonucleated cyst-producing Entamoeba species. Molecular diversity indexes revealed a high interspecific diversity for tetra- and octonucleated Entamoeba spp. (H ± SD = 0.9625 ± 0.0126). The intraspecific diversity varied according to species or subtype: E. dispar and E. histolytica showed lower diversity than E. coli subtypes ST1 and ST2 and E. hartmanni.
Tetra- and octonucleated cyst-producing Entamoeba are endemic in the studied communities; E. histolytica was found in a low proportion and only in the Amazon biome. With regard to E. coli, subtype ST2 was predominant in the Amazon biome. The molecular epidemiology of Entamoeba spp. is a field to be further explored and provides information with important implications for public health.
人类携带的内阿米巴物种具有不同程度的致病性。本研究旨在探索不同巴西地区四核和八核产囊内阿米巴的种内和种间多样性、系统发育关系、流行率和分布。
进行了横断面研究，以收集来自四个巴西生物群落（大西洋森林、卡廷加、塞拉多和亚马逊）的社区的粪便样本（n=1728）和社会人口学数据。通过部分小亚基核糖体 DNA 测序（SSU rDNA）进行分子分析，并进行系统发育分析。
光镜分析显示，所有研究的生物群落中均发现四核囊。年龄组为 6-10 岁的阳性率最高（23.21%）。对于八核囊，阳性率范围为 1-55.1%。获得了 60 个 SSU rDNA 内阿米巴序列，鉴定出四种不同的物种：八核的大肠杆菌和四核的溶组织内阿米巴、迪斯帕内阿米巴和哈氏内阿米巴。还鉴定了新的单倍型（n=32），但未鉴定出新的核糖体谱系。大肠杆菌 ST1 亚型在大西洋森林和卡廷加占优势，而亚马逊生物群落中 ST2 亚型占优势。仅在亚马逊生物群落中检测到溶组织内阿米巴。在系统发育树中，序列分为两组，第一组包含单核和四核，第二组包含单核和八核产囊内阿米巴。分子多样性指数显示四核和八核产囊内阿米巴的种间多样性很高（H±SD=0.9625±0.0126）。种内多样性因物种或亚型而异：迪斯帕内阿米巴和溶组织内阿米巴的多样性低于大肠杆菌 ST1 和 ST2 亚型和哈氏内阿米巴。
四核和八核产囊内阿米巴在研究社区中呈地方性流行；溶组织内阿米巴的比例较低，仅在亚马逊生物群落中发现。关于大肠杆菌，亚马逊生物群落中 ST2 亚型占优势。内阿米巴属的分子流行病学是一个有待进一步探索的领域，为公共卫生提供了具有重要意义的信息。
