Grupo BCEI, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia.
Grupo BCEI, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia.
Ticks Tick Borne Dis. 2018 Jul;9(5):1286-1295. doi: 10.1016/j.ttbdis.2018.05.009. Epub 2018 May 21.
Anaplasma marginale is the most prevalent vector-borne pathogen in the livestock industry in Colombia, causing economic losses of approximately USD 4.2 million per year. The present study reports the seasonal transmission patterns, genetic diversity and phylogeographic traits of A. marginale strains in cattle and buffaloes from Colombian livestock areas. A three-point longitudinal survey was designed to evaluate the above characteristics of farms in the Caribbean and Orinoquía regions. The A. marginale prevalence was evaluated in 1432 cattle blood samples, 152 buffalo blood samples and the hemolymph of 439 ticks using semi-nested PCR (sn-PCR) targeting the msp5 gene. The molecular prevalence in cattle and buffaloes was 54.8% and 13.1%, respectively, with higher values during the wet and late wet seasons. Factors such as age and production system were significantly associated with the infection. Rhipicephalus microplus was the only carrier of A. marginale DNA, with an infection rate of 17.2%. On the other hand, the tandem repeat and microsatellite analyses of the msp1α gene showed high genetic diversity and new tandem repeats that suggested strain adaptation to different transmission modes. Phylogeographic analysis using the msp4 gene showed a relationship between Colombian isolates and Mexican, Brazilian, Venezuelan, European and Asian isolates, as well as two worldwide haplogroups that were associated with the geographical origin of each isolate. In conclusion, this study shows that A. marginale occurs under enzootic stability in both hosts, with a high prevalence of infection during wet months and in animals dedicated to beef production. The genetic variability analyses suggest that a high strain diversity is associated with multiple selective pressures in the study area, while phylogeographic traits suggest a high genetic similarity between Mexican and South American strains.
边缘无浆体（Anaplasma marginale）是哥伦比亚畜牧业中最普遍的媒介传播病原体，每年造成约 420 万美元的经济损失。本研究报告了哥伦比亚畜牧区牛和水牛中边缘无浆体菌株的季节性传播模式、遗传多样性和系统地理学特征。设计了一个三点纵向调查，以评估加勒比和奥里诺科地区农场的上述特征。使用针对 msp5 基因的半巢式 PCR（sn-PCR）评估了 1432 份牛血样、152 份水牛血样和 439 份蜱血样中的边缘无浆体流行情况。牛和水牛的分子流行率分别为 54.8%和 13.1%，湿季和晚湿季较高。年龄和生产系统等因素与感染显著相关。只有微小璃眼蜱（Rhipicephalus microplus）携带边缘无浆体 DNA，感染率为 17.2%。另一方面，msp1α 基因的串联重复和微卫星分析显示出较高的遗传多样性和新的串联重复，表明菌株适应不同的传播方式。使用 msp4 基因进行的系统地理学分析表明，哥伦比亚分离株与墨西哥、巴西、委内瑞拉、欧洲和亚洲分离株以及与每个分离株的地理起源相关的两个全球单倍型群之间存在关系。总之，本研究表明，边缘无浆体在这两种宿主中处于地方性稳定状态，在潮湿月份和专门用于牛肉生产的动物中感染率较高。遗传变异分析表明，高菌株多样性与研究区域内的多种选择压力有关，而系统地理学特征表明，墨西哥和南美洲菌株之间存在高度的遗传相似性。
