Jamerson Melissa, Schmoyer Jacqueline A, Park Jay, Marciano-Cabral Francine, Cabral Guy A
Department of Clinical Laboratory Sciences, Virginia Commonwealth University School of Allied Health Professions, Richmond, VA 23298-0583, USA.
Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0678, USA.
Microbiology (Reading). 2017 Mar;163(3):322-332. doi: 10.1099/mic.0.000428. Epub 2017 Mar 23.
Naegleria fowleri (N. fowleri) causes primary amoebic meningoencephalitis, a rapidly fatal disease of the central nervous system. N. fowleri can exist in cyst, flagellate or amoebic forms, depending on environmental conditions. The amoebic form can invade the brain following introduction into the nasal passages. When applied intranasally to a mouse model, cultured N. fowleri amoebae exhibit low virulence. However, upon serial passage in mouse brain, the amoebae acquire a highly virulent state. In the present study, a proteomics approach was applied to the identification of N. fowleri amoeba proteins whose expression was associated with the highly virulent state in mice. Mice were inoculated intranasally with axenically cultured amoebae or with mouse-passaged amoebae. Examination by light and electron microscopy revealed no morphological differences. However, mouse-passaged amoebae were more virulent in mice as indicated by exhibiting a two log10 titre decrease in median infective dose 50 (ID50). Scatter plot analysis of amoebic lysates revealed a subset of proteins, the expression of which was associated with highly virulent amoebae. MS-MS indicated that this subset contained proteins that shared homology with those linked to cytoskeletal rearrangement and the invasion process. Invasion assays were performed in the presence of a select inhibitor to expand on the findings. The collective results suggest that N. fowleri gene products linked to cytoskeletal rearrangement and invasion may be candidate targets in the management of primary amoebic meningoencephalitis.
福氏耐格里阿米巴（N. fowleri）可引发原发性阿米巴脑膜脑炎，这是一种中枢神经系统的快速致死性疾病。福氏耐格里阿米巴可根据环境条件以包囊、鞭毛体或阿米巴形态存在。阿米巴形态可在进入鼻腔后侵入大脑。将培养的福氏耐格里阿米巴经鼻应用于小鼠模型时，其毒力较低。然而，在小鼠脑内连续传代后，阿米巴会获得高毒力状态。在本研究中，采用蛋白质组学方法来鉴定福氏耐格里阿米巴的蛋白质，其表达与小鼠体内的高毒力状态相关。给小鼠经鼻接种无菌培养的阿米巴或经小鼠传代的阿米巴。光镜和电镜检查未发现形态学差异。然而，经小鼠传代的阿米巴在小鼠体内毒力更强，表现为半数感染剂量50（ID50）的滴度降低了两个对数10。对阿米巴裂解物的散点图分析揭示了一组蛋白质，其表达与高毒力阿米巴相关。串联质谱（MS-MS）表明，该组蛋白质与那些与细胞骨架重排和侵袭过程相关的蛋白质具有同源性。在存在一种选择性抑制剂的情况下进行侵袭试验以拓展这些发现。总体结果表明，与细胞骨架重排和侵袭相关的福氏耐格里阿米巴基因产物可能是原发性阿米巴脑膜脑炎治疗中的候选靶点。
