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Fish Shellfish Immunol. 2020 Aug;103:190-199. doi: 10.1016/j.fsi.2020.05.004. Epub 2020 May 11.
The host:parasite interactions of the 3 serious haplosporidian pathogens of oysters, on which most information exists, are reviewed. They are Bonamia ostreae in Ostrea spp. and Crassostrea gigas; Bonamia exitiosa in Ostrea spp.; and Haplosporidium nelsoni in Crassostrea spp. Understanding the haemocytic response to pathogens is constrained by lack of information on haematopoiesis, haemocyte identity and development. Basal haplospridians in spot prawns are probably facultative parasites. H. nelsoni and a species infecting Haliotis iris in New Zealand (NZAP), which have large extracellular plasmodia that eject haplosporosomes or their contents, lyse surrounding cells and are essentially extracellular parasites. Bonamia spp. have small plasmodia that are phagocytosed, haplosporosomes are not ejected and they are intracellular obligate parasites. Phagocytosis by haemocytes is followed by formation of a parasitophorous vacuole, blocking of haemocyte lysosomal enzymes and the endolysosomal pathway. Reactive oxygen species (ROS) are blocked by antioxidants, and host cell apoptosis may occur. Unlike susceptible O. edulis, the destruction of B. ostreae by C. gigas may be due to higher haemolymph proteins, higher rates of granulocyte binding and phagocytosis, production of ROS, the presence of plasma β-glucosidase, antimicrobial peptides and higher levels of haemolymph and haemocyte enzymes. In B.exitiosa infection of Ostrea chilensis, cytoplasmic lipid bodies (LBs) containing lysosomal enzymes accumulate in host granulocytes and in B. exitiosa following phagocytosis. Their genesis and role in innate immunity and inflammation appears to be the same as in vertebrate granulocytes and macrophages, and other invertebrates. If so, they are probably the site of eicosanoid synthesis from arachidonic acid, and elevated numbers of LBs are probably indicative of haemocyte activation. It is probable that the molecular interaction, and role of LBs in the synthesis and storage of eicosanoids from arachidonic acid, is conserved in innate immunity in vertebrates and invertebrates. However, it seems likely that haplosporidians are more diverse than realized, and that there are many variations in host parasite interactions and life cycles.
本文回顾了三种严重的牡蛎哈氏胞子虫病原体（即牡蛎派琴虫、牡蛎 Bonamia exitiosa 和扇贝哈氏胞子虫）与宿主的相互作用。这些病原体在牡蛎和巨牡蛎中引起的 Bonamia ostreae 感染，在牡蛎中引起的 Bonamia exitiosa 感染，以及在扇贝中引起的 Haplosporidium nelsoni 感染。由于缺乏造血、血细胞身份和发育方面的信息，对血细胞对病原体的反应的理解受到限制。斑点对虾中的基础哈氏胞子虫可能是兼性寄生虫。H. nelsoni 和一种感染新西兰虹彩贝（NZAP）的物种，它们具有大型的细胞外原质体，可排出哈氏胞子体或其内容物，溶解周围的细胞，基本上是细胞外寄生虫。Bonamia spp. 具有较小的原质体，可被吞噬，哈氏胞子体不被排出，是细胞内专性寄生虫。血细胞吞噬后，形成一个寄生空泡，阻断溶酶体酶和内溶酶体途径。活性氧（ROS）被抗氧化剂阻断，宿主细胞可能发生凋亡。与易感的 O. edulis 不同，C. gigas 对 B. ostreae 的破坏可能是由于其血液中具有更高的蛋白、更高的粒细胞结合和吞噬率、ROS 的产生、血浆 β-葡糖苷酶的存在、抗菌肽以及更高水平的血液和血细胞酶。在奥斯特拉·奇伦西斯的 B. exitiosa 感染中，细胞质脂滴（LBs）含有溶酶体酶，在宿主粒细胞和吞噬后的 B. exitiosa 中积累。它们的起源和在先天免疫和炎症中的作用与脊椎动物粒细胞和巨噬细胞以及其他无脊椎动物相同。如果是这样，它们可能是花生四烯酸合成类二十烷酸的部位，并且 LB 的数量增加可能表明血细胞激活。分子相互作用以及 LB 在从花生四烯酸合成和储存类二十烷酸中的作用，在脊椎动物和无脊椎动物的先天免疫中可能是保守的。然而，似乎哈氏胞子虫比人们意识到的更加多样化，宿主-寄生虫相互作用和生命周期存在许多变化。
