Frenette Aaron P, Eydal Matthías, Hansen Haakon, Burt Michael D B, Duffy Michael S
Department of Biology, University of New Brunswick, Fredericton, NB, E3B 5A3, Canada.
Institute for Experimental Pathology at Keldur, University of Iceland, Keldnavegur 3, 112, Reykjavik, Iceland.
J Eukaryot Microbiol. 2017 Jan;64(1):67-77. doi: 10.1111/jeu.12339. Epub 2016 Jul 13.
Microsporidia are fungal parasites that infect diverse invertebrate and vertebrate hosts. Finfish aquaculture supports epizootics due to high host density and the high biotic potential of these parasites. Reliable methods for parasite detection and identification are a necessary precursor to empirical assessment of strategies to mitigate the effects of these pathogens during aquaculture. We developed an integrative approach to detect and identify Loma morhua infecting Atlantic cod. We show that the spleen is more reliable than the commonly presumed gills as best organ for parasite detection in spite of substantial morphological plasticity in xenoma complexes. We developed rDNA primers with 100% sensitivity in detecting L. morhua and with utility in distinguishing some congeneric Loma species. ITS sequencing is necessary to distinguish L. morhua from other congeneric microsporidia due to intraspecific nucleotide variation. 64% of L. morhua ITS variants from Atlantic cod have a 9-nucleotide motif that distinguishes it from Loma spp. infecting non-Gadus hosts. The remaining 36% of ITS variants from Atlantic cod are distinguished from currently represented Loma spp., particularly those infecting Gadus hosts, based on a 14-nucleotide motif. This research approach is amenable to developing templates in support of reliable detection and identification of other microsporidian parasites in fishes.
微孢子虫是感染多种无脊椎动物和脊椎动物宿主的真菌寄生虫。由于宿主密度高以及这些寄生虫的高生物潜能，鱼类养殖助长了疾病流行。可靠的寄生虫检测和鉴定方法是在水产养殖中对减轻这些病原体影响的策略进行实证评估的必要前提。我们开发了一种综合方法来检测和鉴定感染大西洋鳕鱼的莫氏洛马虫。我们表明，尽管异核体复合体存在显著的形态可塑性，但脾脏作为检测寄生虫的最佳器官比通常认为的鳃更可靠。我们开发了rDNA引物，其在检测莫氏洛马虫方面具有100%的灵敏度，并且可用于区分一些同属的洛马属物种。由于种内核苷酸变异，需要进行ITS测序来区分莫氏洛马虫与其他同属微孢子虫。来自大西洋鳕鱼的64%的莫氏洛马虫ITS变体具有一个9核苷酸基序，可将其与感染非鳕属宿主的洛马属物种区分开来。基于一个14核苷酸基序，来自大西洋鳕鱼的其余36%的ITS变体与目前已知的洛马属物种区分开来，特别是那些感染鳕属宿主的物种。这种研究方法适合开发模板，以支持可靠地检测和鉴定鱼类中的其他微孢子虫寄生虫。
