Aktas Munir, Özübek Sezayi
Department of Parasitology, College of Veterinary Medicine, Firat University, 23119 Elazig, Turkey.
Department of Parasitology, College of Veterinary Medicine, Firat University, 23119 Elazig, Turkey.
Comp Immunol Microbiol Infect Dis. 2017 Oct;54:20-26. doi: 10.1016/j.cimid.2017.07.008. Epub 2017 Aug 4.
During early lactation, dairy cows may present a transient immunosuppressive state and develop anaplasmosis caused by Anaplasma marginale. In this study, clinical anaplasmosis in dairy cattle in the Thrace region of Turkey was investigated with respect to within-herd prevalence, vertical transmission, and genetic diversity. In March and September 2015, thirty lactating cows showed primary clinical signs of anaplasmosis, including fever, anaemia, decreased milk yield, anorexia, and laboured breathing. Symptoms disappeared in most cows after administration of long-acting oxytetracycline, but nine of them (30%) died. Following diagnosis based on clinical signs, microscopy and molecular findings, blood samples were collected from apparently healthy lactating cows (n=184), pregnant heifers (n=39) and newborn calves (n=24). DNA was extracted from each sample and analyzed for the presence of major surface proteins (MSPs) of A. marginale, followed by sequencing to assess diversity of isolates. Microscopic examination of erythrocytes revealed A. marginale inclusion bodies in symptomatic cows. Examination of thin blood smears showed 3.8% of the lactating, clinically asymptomatic, cows to be infected with A. marginale, while nPCR detected 31.0% positive. A. marginale infection was not detected in pregnant heifers by either method. Congenital infection was found in one calf by nPCR. This is the first report of transplacental transmission of A. marginale in Turkey. The MSP4 sequence analyses showed high genetic diversity among the isolates, presenting 97.6-99.6% homology at the amino acid level. The sequences of MSP1a amplicons revealed genetic diversity providing three new tandem repeats.
在泌乳早期,奶牛可能会出现短暂的免疫抑制状态,并感染由边缘无浆体引起的无浆体病。在本研究中,针对土耳其色雷斯地区奶牛群内无浆体病的流行情况、垂直传播及遗传多样性,对临床无浆体病展开了调查。2015年3月和9月,30头泌乳奶牛出现了无浆体病的主要临床症状,包括发热、贫血、产奶量下降、厌食和呼吸困难。大多数奶牛在注射长效土霉素后症状消失,但其中9头(30%)死亡。根据临床症状、显微镜检查和分子检测结果做出诊断后,从表面健康的泌乳奶牛(n = 184)、怀孕的小母牛(n = 39)和新生犊牛(n = 24)采集了血样。从每个样本中提取DNA,分析边缘无浆体主要表面蛋白(MSP)的存在情况,随后进行测序以评估分离株的多样性。对红细胞的显微镜检查在有症状的奶牛中发现了边缘无浆体包涵体。对薄血涂片的检查显示,3.8%的泌乳且无临床症状的奶牛感染了边缘无浆体,而巢式PCR检测到31.0%呈阳性。两种方法均未在怀孕小母牛中检测到边缘无浆体感染。通过巢式PCR在1头犊牛中发现了先天性感染。这是土耳其关于边缘无浆体经胎盘传播的首次报道。MSP4序列分析显示分离株之间存在高度遗传多样性,在氨基酸水平上具有97.6 - 99.6%的同源性。MSP1a扩增子的序列显示出遗传多样性,提供了3个新的串联重复序列。