Instituto de Ciencias Clínicas Veterinarias, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile.
Departamento de Patologia Veterinária, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista (FCAV/UNESP), Jaboticabal, SP, Brazil.
Ticks Tick Borne Dis. 2020 Jul;11(4):101441. doi: 10.1016/j.ttbdis.2020.101441. Epub 2020 Apr 16.
Anaplasma phagocytophilum is the causative agent of equine granulocytic anaplasmosis (EGA). This study aimed to perform serological and molecular surveys of A. phagocytophilum in thoroughbred horses from racecourses in Chile. Additionally, hematological findings related to A. phagocytophilum molecular positivity were addressed, and phylogenetic analysis of selected positive samples was performed. Complete blood count and msp2 gene real-time PCR were performed in 457 thoroughbred horses from three racecourses located in three different cities of Chile (Santiago, Viña del Mar and Concepción). Sera from horses in two racecourses (Santiago and Vina del Mar) were tested by Indirect fluorescent antibody test (IFAT) to detect IgG antibodies against A. phagocytophilum. The occurrence of A. phagocytophilum by real-time PCR was 13.6 % (62/457, 95 % CI: 10.8-16.3 %), with the highest occurrence observed in Santiago (26.5 %), followed by Concepción (9%), and the lowest in Viña del Mar (5%). The overall frequency of IgG antibodies to A. phagocytophilum was 7.9 % (23/290, 95 % CI: 4.8-12.7 %), with 9.9 % in Santiago and 6.5 % in Viña del Mar. Only three animals from Santiago Racecourse were positive in both real-time PCR and serology. PCR-positive horses from Santiago racecourse presented significantly lower hemoglobin, mean corpuscular value (MCV), and mean corpuscular hemoglobin concentration (CHCM), and higher eosinophil counts. Phylogenetic analysis based on the msp2 gene showed that A. phagocytophilum sequences found in the present study were closely related with A. phagocytophilum sequences from the USA and Europe. Anaplasma phagocytophilum DNA is detected for the first time in Chile.
嗜吞噬细胞无形体是马粒细胞无形体病（EGA）的病原体。本研究旨在对智利赛马场的纯种马进行嗜吞噬细胞无形体的血清学和分子调查。此外，还研究了与嗜吞噬细胞无形体分子阳性相关的血液学发现，并对选定的阳性样本进行了系统发育分析。对来自智利三个城市（圣地亚哥、比尼亚德尔马和康塞普西翁）三个赛马场的 457 匹纯种马进行了全血计数和 msp2 基因实时 PCR。对来自圣地亚哥和比尼亚德尔马两个赛马场的马血清进行了间接荧光抗体试验（IFAT），以检测针对嗜吞噬细胞无形体的 IgG 抗体。实时 PCR 检测到嗜吞噬细胞无形体的发生率为 13.6%（62/457，95%CI：10.8-16.3%），其中圣地亚哥最高（26.5%），其次是康塞普西翁（9%），比尼亚德尔马最低（5%）。针对嗜吞噬细胞无形体的 IgG 抗体总频率为 7.9%（23/290，95%CI：4.8-12.7%），圣地亚哥为 9.9%，比尼亚德尔马为 6.5%。只有来自圣地亚哥赛马场的三只动物在实时 PCR 和血清学上均为阳性。来自圣地亚哥赛马场的 PCR 阳性马的血红蛋白、平均红细胞体积（MCV）和平均红细胞血红蛋白浓度（CHCM）明显较低，嗜酸性粒细胞计数较高。基于 msp2 基因的系统发育分析表明，本研究中发现的嗜吞噬细胞无形体序列与来自美国和欧洲的嗜吞噬细胞无形体序列密切相关。嗜吞噬细胞无形体 DNA 首次在智利被检测到。
