Bivalve molluscs are now considered indicator species of aquatic contamination by human parasitic protozoa. Nonetheless, the possible effects of these protozoa on the immune system of their paratenic hosts are poorly documented. The aim of this study was to evaluate the effects of two protozoa on hemocyte viability and phagocytosis from two mussels, the zebra mussel (freshwater habitat) and the blue mussel (seawater habitat). For these purposes, viability and phagocytic markers have been analysed on hemocytes from mussels without biological stress (control hemocytes), and on hemocytes exposed to a biological stress (Toxoplasma gondii and Cryptosporidium parvum oocysts). We report, for the first known time, the interactions between protozoa and hemocytes of mussels from different aquatic environments. Zebra mussel hemocytes showed a decrease in phagocytosis of fluorescent microbeads after exposure to both protozoa, while blue mussel hemocytes reacted only to T. gondii oocysts. These decreases in the ingestion of microbeads can be caused by competition between beads and oocysts and can be influenced by the size of the oocysts. New characterisations of their immune capacities, including aggregation, remain to be developed to understand the specificities of both mussels.

中文翻译：

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从双壳纲紫花贻贝和多形杜鹃提取的血细胞的活力和吞噬反应的比较，并暴露于人寄生的原生动物中。

双壳软体动物现在被认为是人类寄生原生动物对水生污染物的指示物种。尽管如此，这些原生动物对其腹痛宿主免疫系统的可能影响却鲜有记载。这项研究的目的是评估两种原生动物对斑马贻贝（淡水生境）和蓝贻贝（淡水生境）两个贻贝的血细胞活力和吞噬作用的影响。为了这些目的，已经对无生物应力的贻贝血细胞（对照血细胞）和暴露于生物应力的血细胞（弓形虫和小隐孢子虫卵囊）进行了活力和吞噬标记的分析。我们首次报道了原生动物与来自不同水生环境的贻贝血细胞之间的相互作用。斑马贻贝血细胞暴露于两个原生动物后，荧光微珠的吞噬作用降低，而蓝色贻贝血细胞仅对弓形虫卵囊反应。微珠摄入的这些减少可能是由于珠与卵囊之间的竞争所致，并且可能受到卵囊大小的影响。它们的免疫能力（包括聚集）的新特征尚待开发，以了解两种贻贝的特异性。