Abstract：
Free-living amoebae (FLA) are potential reservoirs of Legionella in aquatic environments. However, the parasitic relationship between various Legionella and amoebae remains unclear. In this study, surface water samples were gathered from two rivers for evaluating parasitic Legionella. Warmer water temperature is critical to the existence of Legionella. This result suggests that amoebae may be helpful in maintaining Legionella in natural environments because warmer temperatures could enhance parasitisation of Legionella in amoebae. We next used immunomagnetic separation (IMS) to identify extracellular Legionella and remove most free Legionella before detecting the parasitic ones in selectively enriched amoebae. Legionella pneumophila was detected in all the approaches, confirming that the pathogen is a facultative amoebae parasite. By contrast, two obligate amoebae parasites, Legionella-like amoebal pathogens (LLAPs) 8 and 9, were detected only in enriched amoebae. However, several uncultured Legionella were detected only in the extracellular samples. Because the presence of potential hosts, namely Vermamoeba vermiformis, Acanthamoeba spp. and Naegleria gruberi, was confirmed in the samples that contained intracellular Legionella, uncultured Legionella may survive independently of amoebae. Immunomagnetic separation and amoebae enrichment may have referential value for detecting parasitic Legionella in surface waters.
摘要：
自由生活的变形虫（FLA）是水生环境中军团菌的潜在水库。然而,各种军团菌和变形虫之间的寄生关系尚不清楚。在这项研究中,从两条河流收集地表水样本，用于评估寄生军团菌。水温升高对军团菌的存在至关重要。该结果表明，变形虫可能有助于在自然环境中维持军团菌，因为较高的温度会增强变形虫中军团菌的寄生作用。接下来，我们使用免疫磁性分离（IMS）来鉴定细胞外军团菌，并在检测选择性富集的变形虫中的寄生军团菌之前去除大多数游离军团菌。在所有方法中都检测到了嗜肺军团菌,确认病原体是兼性变形虫寄生虫。相比之下,两种专性变形虫寄生虫，仅在富集的变形虫中检测到军团菌样变形虫病原体（LLAP）8和9。然而,仅在细胞外样品中检测到几种未培养的军团菌。因为潜在宿主的存在，即VermamoebaVermiformis，棘阿米巴。和Naegleriagruberi,在含有细胞内军团菌的样本中得到证实，未培养的军团菌可以独立于变形虫存活。免疫磁分离和变形虫富集可能对检测地表水中的寄生军团菌具有参考价值。
