National Institute of Veterinary Research, 86. Truong Chinh Street, Dong Da District, Hanoi, Vietnam.
Department of Biomedical Sciences, Institute of Tropical Medicine, Nationalestraat 155, B2000, Antwerp, Belgium.
Parasit Vectors. 2017 Nov 21;10(1):575. doi: 10.1186/s13071-017-2514-9.
An opisthorchiid liver fluke was recently reported from ducks (Anas platyrhynchos) in Binh Dinh Province of Central Vietnam, and referred to as "Opisthorchis viverrini-like". This species uses common cyprinoid fishes as second intermediate hosts as does Opisthorchis viverrini, with which it is sympatric in this province. In this study, we refer to the liver fluke from ducks as "Opisthorchis sp. BD2013", and provide new sequence data from the mitochondrial (mt) genome and the nuclear ribosomal transcription unit. A phylogenetic analysis was conducted to clarify the basal taxonomic position of this species from ducks within the genus Opisthorchis (Digenea: Opisthorchiidae).
Adults and eggs of liver flukes were collected from ducks, metacercariae from fishes (Puntius brevis, Rasbora aurotaenia, Esomus metallicus) and cercariae from snails (Bithynia funiculata) in different localities in Binh Dinh Province. From four developmental life stage samples (adults, eggs, metacercariae and cercariae), the complete cytochrome b (cob), nicotinamide dehydrogenase subunit 1 (nad1) and cytochrome c oxidase subunit 1 (cox1) genes, and near-complete 18S and partial 28S ribosomal DNA (rDNA) sequences were obtained by PCR-coupled sequencing. The alignments of nucleotide sequences of concatenated cob + nad1 + cox1, and of concatenated 18S + 28S were separately subjected to phylogenetic analyses. Homologous sequences from other trematode species were included in each alignment.
Phylogenetic trees were inferred from concatenated (cob + nad1 + cox1) nucleotide sequences and combined 18S + 28S nucleotide sequences of five Opisthorchis sp. BD2013 samples and additional reference taxa. Both trees demonstrated the anticipated clustering of taxa within the superfamily Opisthorchioidea, the paraphyly of the genus Opisthorchis and the sister-species relationship of Opisthorchis sp. BD2013 with O. viverrini.
While it is likely that Opisthorchis sp. BD2013 is distinct from O. viverrini, it is clearly a sister taxon of O. viverrini within the limited number of Opisthorchis species for which appropriate sequence data are available. The new sequences provided here will assist the diagnosis and the taxonomic clarification of the opisthorchiid species.
最近在越南中南部平定省的鸭子（Anas platyrhynchos）中报告了一种片形吸虫肝吸虫，并被称为“Opisthorchis viverrini-like”。该物种与同省的片形吸虫一样，将普通的鲤科鱼类用作第二中间宿主。在这项研究中，我们将来自鸭子的肝吸虫称为“Opisthorchis sp. BD2013”，并提供了来自线粒体（mt）基因组和核核糖体转录单位的新序列数据。进行了系统发育分析，以阐明该种在片形属（吸虫：片形科）内的基本分类地位。
从平定省不同地区的鸭子中收集成虫和虫卵、鱼类（Puntius brevis、Rasbora aurotaenia、Esomus metallicus）中的肝片形吸虫幼虫和 Bithynia funiculata 中的尾蚴。从四个发育阶段样本（成虫、虫卵、肝片形吸虫幼虫和尾蚴）中，通过 PCR 耦联测序获得完整的细胞色素 b（cob）、烟酰胺脱氢酶亚基 1（nad1）和细胞色素 c 氧化酶亚基 1（cox1）基因，以及近完整的 18S 和部分 28S 核糖体 DNA（rDNA）序列。对串联 cob + nad1 + cox1 和串联 18S + 28S 的核苷酸序列进行了对齐，并分别进行了系统发育分析。每个对齐都包含了来自其他吸虫物种的同源序列。
从 5 个 Opisthorchis sp. BD2013 样本和其他参考分类群的串联（cob + nad1 + cox1）核苷酸序列和组合的 18S + 28S 核苷酸序列推断出了系统发育树。两棵树都证明了超科 Opisthorchioidea 内分类群的预期聚类、片形属的并系性以及 Opisthorchis sp. BD2013 与 O. viverrini 的姐妹种关系。
虽然 Opisthorchis sp. BD2013 很可能与 O. viverrini 不同，但在可获得适当序列数据的有限数量的片形属物种中，它显然是 O. viverrini 的姐妹种。这里提供的新序列将有助于 opisthorchid 物种的诊断和分类澄清。
