Barbet A F, Blentlinger R, Yi J, Lundgren A M, Blouin E F, Kocan K M
Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville USA.
Infect Immun. 1999 Jan;67(1):102-7. doi: 10.1128/IAI.67.1.102-107.1999.
Anaplasma marginale, a tick-borne rickettsial pathogen of cattle, infects bovine erythrocytes, resulting in mild to severe hemolytic disease that causes economic losses in domestic livestock worldwide. Recently, the Virginia isolate of A. marginale was propagated in a continuous tick cell line, IDE8, derived from embryonic Ixodes scapularis. Development of A. marginale in cell culture was morphologically similar to that described previously in ticks. In order to evaluate the potential of the cell culture-derived organisms for use in future research or as an antigen for serologic tests and vaccines, the extent of structural conservation of the major surface proteins (MSPs) between the cell culture-derived A. marginale and the bovine erythrocytic stage, currently the source of A. marginale antigen, was determined. Structural conservation on the tick salivary-gland stage was also examined. Monoclonal and monospecific antisera against MSPs 1 through 5, initially characterized against erythrocyte stages, also reacted with A. marginale from cell culture and tick salivary glands. MSP1a among geographic A. marginale isolates is variable in size because of different numbers of a tandemly repeated 28- or 29-amino-acid peptide. The cell culture-derived A. marginale maintained the same-size MSP1a as that found on the Virginia isolate of A. marginale in bovine erythrocytes and tick salivary glands. Although differences were observed in the polymorphic MSP2 antigen between culture and salivary-gland stages, MSP2 did not appear to vary, by two-dimensional gel electrophoresis, during continuous passage in culture. These data show that MSPs of erythrocyte-stage A. marginale are present on culture stages and may be structurally conserved during continuous culture. The presence of all current candidate diagnostic and vaccine antigens suggests that in vitro cultures are a valuable source of rickettsiae for basic research and for the development of improved diagnostic reagents and vaccines against anaplasmosis.
边缘无形体是一种通过蜱传播的牛立克次氏体病原体，可感染牛红细胞，导致轻度至重度溶血性疾病，给全球家畜业造成经济损失。最近，边缘无形体弗吉尼亚分离株在源自肩突硬蜱胚胎的连续蜱细胞系IDE8中进行了繁殖。边缘无形体在细胞培养中的发育在形态上与先前在蜱中描述的相似。为了评估细胞培养来源的生物体在未来研究中的应用潜力，或作为血清学检测和疫苗的抗原，测定了细胞培养来源的边缘无形体与目前作为边缘无形体抗原来源的牛红细胞阶段之间主要表面蛋白（MSP）的结构保守程度。还检查了蜱唾液腺阶段的结构保守性。最初针对红细胞阶段进行表征的针对MSP1至5的单克隆和单特异性抗血清，也与细胞培养和蜱唾液腺中的边缘无形体发生反应。由于串联重复的28或29个氨基酸肽的数量不同，不同地理区域的边缘无形体分离株中的MSP1a大小可变。细胞培养来源的边缘无形体保持与在牛红细胞和蜱唾液腺中的边缘无形体弗吉尼亚分离株上发现的相同大小的MSP1a。尽管在培养阶段和唾液腺阶段的多态性MSP2抗原中观察到差异，但通过二维凝胶电泳，MSP2在连续传代培养过程中似乎没有变化。这些数据表明，红细胞阶段边缘无形体的MSP存在于培养阶段，并且在连续培养过程中可能在结构上保守。所有当前候选诊断和疫苗抗原的存在表明，体外培养物是立克次氏体的宝贵来源，可用于基础研究以及开发改进的抗无形体病诊断试剂和疫苗。
