International Centre of Excellence for Aquatic Animal Health, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, The Nothe, Weymouth DT4 8UB, UK.
Dis Aquat Organ. 2022 Jul 7;150:1-16. doi: 10.3354/dao03668.
The genera Paramoeba and Neoparamoeba (Amoebozoa, Dactylopodida, Paramoebidae) include well-known opportunistic pathogens associated with fish (N. peruans; amoebic gill disease), lobsters, molluscs and sea urchins, but only rarely with crabs (grey crab disease of blue crabs). Following reports of elevated post-capture mortality in edible crabs Cancer pagurus captured from a site within the English Channel fishery in the UK, a novel disease (amoebic crab disease, ACD) was detected in significant proportions of the catch. We present histopathological, transmission electron microscopy and molecular phylogenetic data, showing that this disease is defined by colonization of haemolymph, connective tissues and fixed phagocytes by amoeboid cells, leading to tissue destruction and presumably death in severely diseased hosts. The pathology was strongly associated with a novel amoeba with a phylogenetic position on 18S rRNA gene trees robustly sister to Janickina pigmentifera (which groups within the current circumscription of Paramoeba/Neoparamoeba), herein described as Janickina feisti n. sp. We provide evidence that J. feisti is associated with ACD in 50% of C. pagurus sampled from the mortality event. A diversity of other paramoebid sequence types, clustering with known radiations of N. pemaquidensis and N. aestuarina and a novel N. aestuarina sequence type, was detected by PCR in most of the crabs investigated, but their detection was much less strongly associated with clinical signs of disease. The discovery of ACD in edible crabs from the UK is discussed relative to published historical health surveys for this species.
（属名）假变形虫和新假变形虫（肉足虫亚门，变形目，变形科）包括与鱼类（新毕氏副棘盘虫；变形虫鳃病）、龙虾、软体动物和海胆相关的著名机会性病原体，但很少与螃蟹（蓝蟹的灰蟹病）有关。在英国英吉利海峡渔业中捕获的食用蟹（欧洲黄道蟹）出现高死亡率后，在捕获的螃蟹中发现了一种新疾病（变形虫性蟹病，ACD）。我们提供了组织病理学、透射电子显微镜和分子系统发育数据，表明这种疾病的特征是变形虫样细胞定殖于血淋巴、结缔组织和固定吞噬细胞，导致组织破坏，严重患病的宿主可能死亡。这种病理学与一种新型变形虫密切相关，这种变形虫在 18S rRNA 基因树中的系统发育位置与 Janickina pigmentifera （属于假变形虫/新假变形虫的当前分类群）非常接近，本文将其描述为 Janickina feisti n. sp. 我们提供的证据表明，在与死亡率事件相关的 50%的 C. pagurus 样本中，J. feisti 与 ACD 有关。通过 PCR 在大多数受调查的螃蟹中检测到了其他变形虫序列类型的多样性，这些序列类型与已知的 N. pemaquidensis 和 N. aestuarina 辐射群以及一种新型 N. aestuarina 序列类型聚类，但它们的检测与疾病的临床症状相关性较弱。本文讨论了英国食用蟹 ACD 的发现与该物种的历史健康调查的关系。
