de la Fuente José, Blouin Edmour F, Kocan Katherine M
Department of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
Clin Diagn Lab Immunol. 2003 Jan;10(1):182-4. doi: 10.1128/cdli.10.1.182-184.2003.
Anaplasma marginale is a tick-borne, rickettsial cattle pathogen that is endemic in several areas of the United States. Recent studies (J. de la Fuente, J. C. Garcia-Garcia, E. F. Blouin, J. T. Saliki, and K. M. Kocan, Clin. Diagn. Lab. Immunol. 9:658-668, 2002) demonstrated that infection of cultured tick cells and bovine erythrocytes with one genotype of A. marginale excluded infection with other genotypes, a phenomenon referred to as infection exclusion. The present study was undertaken to confirm the phenomenon of infection exclusion of A. marginale genotypes in a tick vector, Dermacentor variabilis. Only one genotype of A. marginale (Virginia isolate) was detected by PCR in ticks that fed first on a calf infected with a Virginia isolate and second on a calf infected with an Oklahoma isolate. These studies demonstrate that infection exclusion of A. marginale genotypes also occurs in naturally infected ticks, as well as in cattle and cultured tick cells, and results in establishment of only one genotype per tick.
边缘无形体是一种通过蜱传播的立克次氏体牛病原体,在美国的几个地区流行。最近的研究(J. de la Fuente、J. C. Garcia-Garcia、E. F. Blouin、J. T. Saliki和K. M. Kocan,《临床诊断实验室免疫学》9:658 - 668,2002年)表明,用一种基因型的边缘无形体感染培养的蜱细胞和牛红细胞会排除其他基因型的感染,这种现象被称为感染排除。本研究旨在证实边缘无形体基因型在蜱传播媒介变异革蜱中的感染排除现象。在首先以感染弗吉尼亚分离株的小牛为食、其次以感染俄克拉荷马分离株的小牛为食的蜱中,通过PCR仅检测到一种基因型的边缘无形体(弗吉尼亚分离株)。这些研究表明,边缘无形体基因型的感染排除在自然感染的蜱以及牛和培养的蜱细胞中也会发生,并且导致每只蜱仅建立一种基因型。