Munderloh Ulrike G, Yabsley Michael J, Murphy Staci M, Luttrell M Page, Howerth Elizabeth W
Department of Entomology, University of Minnesota, St Paul, MN 55108, USA.
Vector Borne Zoonotic Dis. 2007 Fall;7(3):418-25. doi: 10.1089/vbz.2007.0640.
Feral animals are reservoirs of emerging human pathogens, as well as carriers of closely related wildlife diseases. The latter may interfere with epidemiologic studies by inducing cross-reactive antibodies, or by providing false positive signals in PCR based tests. We cultured a novel intracellular bacterium from the blood of two raccoons (Procyon lotor): RAC413 and RAC414. RAC413 had been experimentally inoculated with blood from a wild-caught raccoon, and provided the material for a blood passage into RAC414. The microbes grew in Ixodes scapularis (black-legged tick) cells, line ISE6, inoculated either with the leukocyte or erythrocyte fraction of anticoagulated blood. Giemsa-stained cells sampled two and three months after initial inoculation of the cultures revealed inclusions similar to those of Ehrlichia sp., except that individual bacteria commonly were elongated and clustered within endosomes. Electronmicroscopy confirmed the presence of irregularly shaped bacteria with evenly granular bacterioplasm bounded by a unit membrane. 16S rDNA sequencing identified the microbes as the raccoon Ehrlichia-like agent previously detected in feral raccoons from Georgia, United States. In conclusion, the availability of a culture isolate of this agent will facilitate future studies to determine its biology, epidemiologic significance, vector association, and host range. The Ehrlichia-like agent infecting raccoons joins a growing list of tick-borne agents cultivable in tick cells.
野生动物是新出现的人类病原体的宿主，也是密切相关的野生动物疾病的携带者。后者可能会通过诱导交叉反应抗体，或在基于聚合酶链反应（PCR）的检测中提供假阳性信号，干扰流行病学研究。我们从两只浣熊（北美浣熊）的血液中培养出一种新型细胞内细菌：RAC413和RAC414。RAC413曾被用一只野生捕获的浣熊的血液进行过实验接种，并为将血液传给RAC414提供了材料。这些微生物在肩胛硬蜱（黑脚蜱）细胞系ISE6中生长，该细胞系接种了抗凝血液的白细胞或红细胞部分。在最初接种培养物后两到三个月采集的吉姆萨染色细胞显示出与埃立克体属细菌相似的包涵体，只是单个细菌通常呈细长形并聚集在内体中。电子显微镜证实存在形状不规则的细菌，其细菌质均匀呈颗粒状，由单位膜包被。16S核糖体DNA测序将这些微生物鉴定为先前在美国佐治亚州的野生浣熊中检测到的浣熊埃立克体样病原体。总之，这种病原体培养分离株的可得性将有助于未来的研究，以确定其生物学特性、流行病学意义、与媒介的关联以及宿主范围。感染浣熊的埃立克体样病原体加入了越来越多可在蜱细胞中培养的蜱传病原体的行列。
