Chen Hui-Yu, Shih Hsiu-Hui
Department of Life Science, National Taiwan University, Taipei 10617, Taiwan, ROC.
Department of Life Science, National Taiwan University, Taipei 10617, Taiwan, ROC.
Acta Trop. 2015 May;145:61-7. doi: 10.1016/j.actatropica.2015.02.011. Epub 2015 Feb 27.
Anisakid nematodes have been found in a variety of marine fishes throughout the world and they are known to cause anisakiasis in human hosts. The present study investigated the prevalence of potentially zoonotic anisakid larvae in spotted mackerel caught from Taiwanese waters where fish represents an important food sources. Anisakis third-stage larvae (L3, n=502) were isolated from 250 spotted mackerel Scomber australasicus. Anisakis L3 larvae were divided morphologically into two types, Anisakis type I larvae had a longer ventriculus and mucron while type II larvae had a shorter ventriculus and no mucron. Anisakis species were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the internal transcribed spacer (ITS) regions of ribosomal DNA and direct sequencing. A simple molecular taxonomic key, utilizing RFLP by two restriction enzymes HinfI and HhaI, enabled the differentiation of the genus Anisakis. The prevalence, mean intensity and mean abundance of Anisakis nematodes recorded for the total specimens were 72.8%, 2.8 (1-15) and 2.0 (0-15), respectively. Anisakis pegreffii was determined to be the dominant species (prevalence=57.2%) and important agent of human anisakiasis. A recombinant genotype (Anisakis simplex sensu stricto × A. pegreffii) was identified as the subdominant species (25.3%) followed by Anisakis typica (10%), Anisakis physeteris (4.0%), Anisakis paggiae (3.0%) and Anisakis brevispiculata (0.5%). The topology of the maximum likelihood and neighbor-joining trees show two well supported clades: one includes the species of A. pegreffii and the other includes A. paggiae, A. physeteris and A. brevispiculata, while A. typica has basal position to all other Anisakis spp. analyzed. This study advances our knowledge of the prevalence of different Anisakis spp. in the spotted mackerel from Taiwanese waters, which is helpful for monitoring the fish populations throughout a diverse array of aquatic ecosystems. More importantly, we provide the concise characterization of multiple Anisakis spp. by PCR-RFLP, which could also be applicable for the rapid diagnosis of human anisakiasis.
异尖线虫已在世界各地的多种海洋鱼类中被发现，并且已知它们会在人类宿主中引起异尖线虫病。本研究调查了从台湾海域捕获的斑点马鲛鱼中潜在人畜共患异尖线虫幼虫的流行情况，在台湾，鱼类是重要的食物来源。从250条澳大利亚鲭（Scomber australasicus）中分离出502条异尖线虫第三期幼虫（L3）。异尖线虫L3幼虫在形态上分为两种类型，I型幼虫的胃和尾突较长，而II型幼虫的胃较短且无尾突。通过核糖体DNA内部转录间隔区（ITS）区域的聚合酶链反应-限制性片段长度多态性（PCR-RFLP）和直接测序来鉴定异尖线虫种类。一个简单的分子分类学关键，利用两种限制性内切酶HinfI和HhaI的RFLP，能够区分异尖线虫属。记录的所有标本中异尖线虫的流行率、平均感染强度和平均丰度分别为72.8%、2.8（1 - 15）和2.0（0 - 15）。佩氏异尖线虫（Anisakis pegreffii）被确定为优势种（流行率 = 57.2%），也是人类异尖线虫病的重要病原体。一种重组基因型（简单异尖线虫狭义种×佩氏异尖线虫）被鉴定为次优势种（25.3%），其次是典型异尖线虫（10%）、抹香鲸异尖线虫（4.0%）、帕氏异尖线虫（3.0%）和短刺异尖线虫（0.5%）。最大似然树和邻接树的拓扑结构显示出两个得到充分支持的进化枝：一个包括佩氏异尖线虫物种，另一个包括帕氏异尖线虫、抹香鲸异尖线虫和短刺异尖线虫，而典型异尖线虫在所有其他分析的异尖线虫物种中处于基部位置。本研究增进了我们对台湾海域斑点马鲛鱼中不同异尖线虫物种流行情况的了解，这有助于监测各种水生生态系统中的鱼类种群。更重要的是，我们通过PCR-RFLP提供了多种异尖线虫物种的简明特征，这也可用于人类异尖线虫病的快速诊断。
