埃及牛和水牛中的边缘无浆体的流行病学和基因分型以及与梨形虫和其他无浆体科的共感染。
Epidemiology and genotyping of Anaplasma marginale and co-infection with piroplasms and other Anaplasmataceae in cattle and buffaloes from Egypt.
机构信息
Department of Animal Medicine (Infectious Diseases), Faculty of Veterinary Medicine, Assiut University, Assiut, 71526, Egypt.
Institute of Infectology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Sudufer 10, 17493, Greifswald-Insel Riems, Germany.
出版信息
Parasit Vectors. 2020 Sep 29;13(1):495. doi: 10.1186/s13071-020-04372-z.
BACKGROUND
Anaplasma marginale is an obligate intracellular bacterium and the main cause of bovine anaplasmosis in tropical and subtropical regions. In Egypt, data regarding the prevalence of A. marginale in ruminant hosts and of the circulating genotypes is lacking. This study therefore aimed to (i) investigate the presence, epidemiology and genotypes of A. marginale in cattle and buffaloes in Egypt, (ii) to evaluate suitable diagnostic tools and (iii) to identify co-infections of A. marginale with other selected tick-borne pathogens.
METHODS
Blood samples were collected from 394 animals (309 cattle and 85 buffaloes) from three different areas in Egypt. For the detection of A. marginale infection, several tests were compared for their sensitivity and specificity: blood smear analysis, enzyme-linked immunosorbent assay (ELISA), PCR, real-time PCR and reverse line blot (RLB) assay. Co-infections with A. marginale, piroplasms and other Anaplasmataceae were surveyed by RLB while A. marginale genotypes were identified by amplifying and sequencing the partial msp1α gene.
RESULTS
Anaplasma marginale DNA was amplified by qPCR in 68.3% of cattle and 29.4% of buffaloes. RLB showed infection with A. marginale in 50.2% of cattle and 42.5% of buffaloes. Blood smear analysis detected this agent in 16.2% of cattle and 2.4% of buffaloes. ELISA showed specific antibodies against A. marginale in 54.9% of cattle. Anaplasma marginale was associated, in cattle and buffaloes, with several tick-borne pathogens (Theileria annulata, Babesia bovis, Babesia bigemina, Babesia occultans and Anaplasma platys). A significant difference of A. marginale infection level was noticed in cattle, where animals between 3-5-years-old had a higher prevalence (79.2%) compared to those older than 5 years (36.4%) and younger than 3 years (59.7%) and one year (64.5%), respectively (P = 0.002281). Microsatellite analysis identified 15 different genotypes.
CONCLUSIONS
The epidemiological findings revealed high prevalence of A. marginale in cattle and buffaloes in all the investigated areas. The circulation of diverse genotypes was observed, most of these A. marginale genotypes being specific for Egypt. The qPCR assay was confirmed to be the most sensitive tool for detection of A. marginale in cattle and buffaloes even in the carrier state, highlighting the importance of using suitable diagnostic tests.
背景
边缘无浆体（Anaplasma marginale）是一种严格的细胞内细菌，是热带和亚热带地区牛无浆体病的主要病原体。在埃及，关于牛无浆体在反刍宿主中的流行情况以及循环基因型的数据尚不清楚。因此，本研究旨在：（i）调查埃及牛和水牛中边缘无浆体的存在、流行病学和基因型；（ii）评估合适的诊断工具；（iii）鉴定边缘无浆体与其他选定的蜱传病原体的合并感染。
方法
从埃及三个不同地区采集了 394 份动物（309 头牛和 85 头水牛）的血液样本。为了检测边缘无浆体感染，对几种检测方法的敏感性和特异性进行了比较：血涂片分析、酶联免疫吸附试验（ELISA）、PCR、实时 PCR 和反向线印迹（RLB）检测。通过 RLB 检测边缘无浆体与其他蜱传病原体的合并感染，而通过扩增和测序部分 msp1α 基因来鉴定边缘无浆体基因型。
结果
qPCR 扩增显示 68.3%的牛和 29.4%的水牛携带边缘无浆体 DNA。RLB 显示 50.2%的牛和 42.5%的水牛感染边缘无浆体。血涂片分析在 16.2%的牛和 2.4%的水牛中检测到该病原体。ELISA 显示 54.9%的牛对边缘无浆体有特异性抗体。在牛和水牛中，边缘无浆体与几种蜱传病原体（环形泰勒虫、牛巴贝斯虫、双芽巴贝斯虫、边缘无形体和无浆体属的牛无形体）有关。牛的边缘无浆体感染水平存在显著差异，3-5 岁的动物比大于 5 岁（36.4%）、小于 3 岁（59.7%）和 1 岁（64.5%）的动物有更高的患病率（P=0.002281）。微卫星分析鉴定出 15 种不同的基因型。
结论
流行病学研究结果表明，在所有调查地区，牛和水牛的边缘无浆体感染率都很高。观察到多种基因型的循环，其中大多数边缘无浆体基因型是埃及特有的。qPCR 检测被证实是检测牛和水牛中边缘无浆体的最敏感工具，即使在携带状态下也是如此，这凸显了使用合适的诊断工具的重要性。
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