Kocan K M, de la Fuente J, Cabezas-Cruz A
Rev Sci Tech. 2015 Aug;34(2):577-86. doi: 10.20506/rst.34.2.2381.
Summary The genus Anaplasmais one of four distinct genera in the family Anaplasmataceae, which are obligate intracellular pathogens vectored by ticks and found exclusively within parasitophorous vacuoles in the host cell cytoplasm. The 2001 reclassification of the order Rickettsiales expanded the genus Anaplasma, which previously contained pathogens that were host specific for ruminants (A. marginale, A. centrale and A. bovis), by adding A. phagocytophilum, a unification of three organisms previously classified as Ehrlichia (E. equi, E. phagocytophila and the unnamed agent of human granulocytic ehrlichiosis). Also included in the genus Anaplasma were A. bovis (formerly E. bovis), A. platys (formerly E. platys) and Aegyptianella pullorum. Despite the genomic relatedness of the regrouped organisms, many aspects of their biology are diverse, including their host specificity, host cell preferences, major surface proteins (MSPs) and tick vectors. This review focuses on the two most important pathogens: A. marginale, which causes bovine anaplasmosis, and A. phagocytophilum, the aetiologic agent of tick-borne fever in sheep and human granulocytic anaplasmosis, an emerging tick-borne disease of humans. For both pathogens, strain diversity is much greater than previously recognised. While MSPs were found to be useful in phylogenetic studies and strain identification, highly conserved MSPs were found to affect the specificity of serologic tests. Comparison of these two important pathogens highlights the challenges and insight derived from reclassification and molecular analysis, both of which have implications for the development and evaluation of diagnosis and control strategies.
摘要 无形体属是无形体科四个不同属之一，该科是专性细胞内病原体，由蜱传播，仅存在于宿主细胞质的寄生泡内。2001年立克次氏体目的重新分类扩大了无形体属，该属以前包含反刍动物宿主特异性病原体（边缘无形体、中央无形体和牛无形体），现增加了嗜吞噬细胞无形体，它是以前分类为埃立克体的三种生物体（马埃立克体、嗜吞噬细胞埃立克体和人类粒细胞埃立克体病的未命名病原体）的统一体。无形体属还包括牛无形体（以前的牛埃立克体）、血小板无形体（以前的血小板埃立克体）和埃及拉氏菌。尽管重新分类后的生物体在基因组上具有相关性，但其生物学的许多方面存在差异，包括宿主特异性、宿主细胞偏好、主要表面蛋白（MSP）和蜱传播媒介。本综述重点关注两种最重要的病原体：引起牛无浆体病的边缘无形体，以及绵羊蜱传热和人类粒细胞无形体病（一种新出现的人类蜱传疾病）的病原体嗜吞噬细胞无形体。对于这两种病原体，菌株多样性比以前认识到的要大得多。虽然发现MSP在系统发育研究和菌株鉴定中有用，但发现高度保守的MSP会影响血清学检测的特异性。对这两种重要病原体的比较突出了重新分类和分子分析带来的挑战和见解，这两者都对诊断和控制策略的开发和评估具有影响。
