Mtshali M S, de la Fuente J, Ruybal P, Kocan K M, Vicente J, Mbati P A, Shkap V, Blouin E F, Mohale N E, Moloi T P, Spickett A M, Latif A A
Parasitology Research Program, QwaQwa Campus, University of the Free State, Private Bag X13, Phuthaditjhaba 9866, South Africa.
Zoonoses Public Health. 2007;54(1):23-30. doi: 10.1111/j.1863-2378.2007.00998.x.
Bovine anaplasmosis, caused by the tick-borne rickettsia Anaplasma marginale, is endemic in South Africa and results in considerable economic loss to the cattle industry. This study was designed to characterize strains of A. marginale at the molecular level from cattle raised in communal and commercial farms in the north-eastern and south-western regions of the Free State Province, South Africa, that varied in rainfall and vegetation. Seroprevalence to A. marginale was determined in 755 cattle by an Anaplasma spp. competitive enzyme-linked immunosorbent assay and ranged from 44% to 98% and was similar in both regions. While Anaplasma centrale was not targeted in this study, A. marginale infections were identified by species-specific msp1alpha polymerase chain reaction in 129 of 215 of the samples studied. Similar genetic diversity of A. marginale strains was found in both the north-eastern and south-western regions. The sequences of 29 A. marginalemsp1alpha amplicons from South African strains revealed considerable genetic diversity providing 14 new repeat sequences. However, 42% of MSP1a repeat sequences were not unique to this region. These results indicated the presence of common genotypes between South African, American and European strains of A. marginale. Cattle movement between different parts of South Africa was suggested by the presence of identical A. marginale MSP1a genotypes in north-eastern and south-western regions of the Free State Province. Control strategies for anaplasmosis in South Africa should therefore be designed to be protective against genetically heterogeneous strains of A. marginale.
牛无形体病由蜱传播的立克次氏体边缘无形体引起，在南非呈地方性流行，给养牛业造成了相当大的经济损失。本研究旨在从南非自由邦省东北部和西南部不同降雨量和植被的社区农场和商业农场饲养的牛中，在分子水平上对边缘无形体菌株进行特征分析。通过无形体属竞争酶联免疫吸附试验在755头牛中测定了边缘无形体的血清阳性率，范围为44%至98%，两个地区相似。虽然本研究未针对中央无形体，但在所研究的215个样本中的129个样本中，通过种特异性msp1alpha聚合酶链反应鉴定出了边缘无形体感染。在东北部和西南部地区发现了相似的边缘无形体菌株遗传多样性。来自南非菌株的29个边缘无形体msp1alpha扩增子序列显示出相当大的遗传多样性，提供了14个新的重复序列。然而，42%的MSP1a重复序列并非该地区所特有。这些结果表明南非、美国和欧洲的边缘无形体菌株之间存在共同基因型。自由邦省东北部和西南部地区存在相同的边缘无形体MSP1a基因型，这表明南非不同地区之间存在牛的流动。因此，南非无形体病的控制策略应设计为针对遗传异质的边缘无形体菌株具有保护作用。
