Xu W, Raoult D
Unité des Rickettsies, CNRS UPRES-A 6020, Faculté de Médecine, Université de la Mediterranée, Marseille, France.
J Clin Microbiol. 1997 Jul;35(7):1715-21. doi: 10.1128/jcm.35.7.1715-1721.1997.
Rickettsiae are gram-negative, obligate intracellular bacteria which have historically been divided into three groups: the typhus group, the scrub typhus group, and the spotted fever group (SFG). Recently, several new SFG rickettsiae have been characterized, and most of these species are associated with ticks and have, as yet, no known pathogenicity toward humans. Rickettsia massiliae, which is widely distributed in Europe and Africa, is one such rickettsia. In order to investigate the antigenic relationships between R. massiliae and other rickettsial species and to develop a more convenient methodology for identifying R. massiliae, we produced monoclonal antibodies against the type strain (Mtu1T) of R. massiliae by fusing immunized splenocytes with SP2/0-Ag14 myeloma cells. A panel of 16 representatives were selected from the 163 positive hybridomas identified on initial screening, and their secreted monoclonal antibodies were further characterized. The reactivities of these 16 monoclonal antibodies with a large panel of rickettsial species were assessed by the microimmunofluorescence assay. All species of the SFG rickettsiae reacted with the monoclonal antibodies directed against epitopes on lipopolysaccharide, which is the common antigen among the SFG rickettsiae. Some closely related species of the SFG, such as Bar29, "R. aeschlimanni," and R. rhipicephali, showed strong cross-reactivities with the monoclonal antibodies directed against epitopes on the two major high-molecular-mass heat-labile proteins (106 and 120 kDa). In addition, species-specific monoclonal antibodies demonstrated that R. massiliae is antigenically different from other rickettsial species. Moreover, these species-specific monoclonal antibodies were successfully used for identifying R. massiliae in the ticks collected from southern France, and are therefore potentially useful tools in the identification and investigation of R. massiliae in ticks in large-scale field work.
立克次氏体是革兰氏阴性、专性细胞内细菌，历史上被分为三组：斑疹伤寒组、恙虫病组和斑点热组（SFG）。最近，几种新的SFG立克次氏体已被鉴定，其中大多数物种与蜱有关，并且尚未发现对人类有致病性。广泛分布于欧洲和非洲的马赛立克次氏体就是这样一种立克次氏体。为了研究马赛立克次氏体与其他立克次氏体物种之间的抗原关系，并开发一种更便捷的方法来鉴定马赛立克次氏体，我们通过将免疫脾细胞与SP2/0-Ag14骨髓瘤细胞融合，制备了针对马赛立克次氏体模式菌株（Mtu1T）的单克隆抗体。从初次筛选鉴定出的163个阳性杂交瘤中挑选出16个代表，进一步鉴定它们分泌的单克隆抗体。通过微量免疫荧光试验评估这16种单克隆抗体与一大组立克次氏体物种的反应性。SFG立克次氏体的所有物种都与针对脂多糖表位的单克隆抗体发生反应，脂多糖是SFG立克次氏体中的共同抗原。SFG的一些密切相关物种，如Bar29、“阿氏立克次氏体”和头蜱立克次氏体，与针对两种主要高分子量热不稳定蛋白（106和120 kDa）表位的单克隆抗体表现出强烈的交叉反应。此外，种特异性单克隆抗体表明马赛立克次氏体在抗原性上与其他立克次氏体物种不同。此外，这些种特异性单克隆抗体已成功用于鉴定从法国南部采集的蜱中的马赛立克次氏体，因此在大规模野外工作中鉴定和研究蜱中的马赛立克次氏体方面可能是有用的工具。
