Paddock C D, Sumner J W, Shore G M, Bartley D C, Elie R C, McQuade J G, Martin C R, Goldsmith C S, Childs J E
Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
J Clin Microbiol. 1997 Oct;35(10):2496-502. doi: 10.1128/jcm.35.10.2496-2502.1997.
Two new isolates of Ehrlichia chaffeensis (designated Jax and St. Vincent) were obtained from patients with fatal ehrlichial infections. Patients developed characteristic manifestations of severe disease due to E. chaffeensis, including marked thrombocytopenia, pulmonary insufficiency, and encephalopathy. Primary isolation was achieved in DH82 cells; the Jax and St. Vincent isolates were detected within 19 and 8 days postinoculation, respectively. The isolates were characterized by molecular evaluation of the 16S rRNA gene, the groESL heat shock operon, a 120-kDa immunodominant protein gene, and an incompletely characterized repetitive-motif sequence (variable-length PCR target [VLPT]). The sequences were compared with those of the corresponding molecular regions in the type isolate (Arkansas). St. Vincent contained one fewer repeat unit in both the 120-kDa protein gene and the VLPT compared with corresponding sequences of the Jax and Arkansas isolates. 16S rRNA gene sequences from the two new isolates had 100% identity to the corresponding sequences of the 91HE17 and Sapulpa isolates of E. chaffeensis, and to the corrected 16S rRNA gene sequence of the Arkansas isolate. The Jax isolate grew more slowly than the St. Vincent isolate in DH82 cells, and both of the new isolates grew more slowly than the extensively passaged Arkansas isolate. Although specific associations between ehrlichial pathogenicity and genotype were not identified from these comparisons, recovery of this organism from a spectrum of clinical presentations remains an integral step in understanding mechanisms of disease caused by E. chaffeensis.
从患有致命埃立克体感染的患者身上获得了两株新的恰菲埃立克体分离株（分别命名为Jax和圣文森特）。患者出现了由恰菲埃立克体引起的严重疾病的特征性表现，包括明显的血小板减少、肺功能不全和脑病。在DH82细胞中实现了初次分离；Jax和圣文森特分离株分别在接种后19天和8天被检测到。通过对16S rRNA基因、groESL热休克操纵子、一个120 kDa免疫显性蛋白基因以及一个特征不完全明确的重复基序序列（可变长度PCR靶标[VLPT]）进行分子评估来对分离株进行特征鉴定。将这些序列与模式株（阿肯色株）相应分子区域的序列进行比较。与Jax和阿肯色分离株的相应序列相比，圣文森特株在120 kDa蛋白基因和VLPT中均少一个重复单元。两株新分离株的16S rRNA基因序列与恰菲埃立克体的91HE17和萨普尔帕分离株的相应序列以及阿肯色分离株经校正的16S rRNA基因序列具有100%的同一性。Jax分离株在DH82细胞中的生长速度比圣文森特分离株慢，并且这两株新分离株的生长速度均比传代广泛的阿肯色分离株慢。尽管从这些比较中未发现埃立克体致病性与基因型之间的特定关联，但从一系列临床表现中分离出这种微生物仍然是理解恰菲埃立克体所致疾病机制的一个不可或缺的步骤。
