School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
Fish Shellfish Immunol. 2018 Jun;77:214-221. doi: 10.1016/j.fsi.2018.03.056. Epub 2018 Mar 30.
The hard clam (Mercenaria mercenaria) is among the most economically-important marine species along the east coast of the United States, representing the first marine resource in several Northeastern states. The species is rather resilient to infections and the only important disease of hard clams results from an infection caused by Quahog Parasite Unknown (QPX), a protistan parasite that can lead to significant mortality events in wild and aquacultured clam stocks. Though the presence of QPX disease has been documented since the 1960s, little information is available on cellular and molecular interactions between the parasite and the host. This study examined the interactions between the clam immune system and QPX cells. First, the effect of clam plasma on the binding of hemocytes to parasite cells was evaluated. Second, clam plasma proteins that bind QPX cells were identified through proteomic (LC-MS/MS) analyses. Finally, the effect of prior clam exposure to QPX on the abundance of QPX-reactive proteins in the plasma was evaluated. Results showed that plasma factors enhance the attachment of hemocytes to QPX. Among the proteins that specifically bind to QPX cells, several lectins were identified, as well as complement component proteins and proteolytic enzymes. Furthermore, results showed that some of these lectins and complement-related proteins are inducible as their abundance significantly increased following QPX challenge. These results shed light on plasma proteins involved in the recognition and binding of parasite cells and provide molecular targets for future investigations of factors involved in clam resistance to the disease, and ultimately for the selection of resistant clam stocks.
硬壳蛤（Mercenaria mercenaria）是美国东海岸经济价值最高的海洋物种之一，是东北部几个州的第一大海洋资源。该物种对感染具有很强的抵抗力，唯一重要的硬壳蛤疾病是由蛤寄生未知原虫（QPX）感染引起的，这种原生动物寄生虫会导致野生和养殖蛤种群大量死亡。尽管自 20 世纪 60 年代以来就已经记录了 QPX 疾病的存在，但关于寄生虫和宿主之间的细胞和分子相互作用的信息很少。本研究检查了蛤免疫系统与 QPX 细胞之间的相互作用。首先，评估了蛤血浆对血细胞与寄生虫细胞结合的影响。其次，通过蛋白质组学（LC-MS/MS）分析鉴定了与 QPX 细胞结合的蛤血浆蛋白。最后，评估了蛤先前暴露于 QPX 对血浆中 QPX 反应蛋白丰度的影响。结果表明，血浆因子增强了血细胞与 QPX 的附着。在特异性结合 QPX 细胞的蛋白质中，鉴定出了几种凝集素，以及补体成分蛋白和蛋白水解酶。此外，结果表明，其中一些凝集素和补体相关蛋白是可诱导的，因为它们的丰度在 QPX 挑战后显著增加。这些结果揭示了参与识别和结合寄生虫细胞的血浆蛋白，并为未来研究参与蛤抵抗疾病的因素以及最终选择抗性蛤种群提供了分子靶标。
