Molad T, Fleidrovich L, Mazuz M, Fish L, Leibovitz B, Krigel Y, Shkap V
Division of Parasitology, Kimron Veterinary Institute, Bet Dagan 50250, Israel.
Vet Microbiol. 2009 Apr 14;136(1-2):54-60. doi: 10.1016/j.vetmic.2008.10.025. Epub 2008 Oct 31.
The present study was aimed to demonstrate genotypic diversity of Anaplama marginale in infected beef herds grazing within anaplasmosis endemic regions. The genotypic diversity was identified among different herds, within each herd, and also within single animals. The Israeli strains revealed unique characteristics of MSP1a repeats and, in addition to the published repeats, six new tandem repeats designated Is1-5, and Is9 were identified. The superinfections of individual Anaplama centrale vaccinated animals with two genotypically different A. marginale strains were detected. Six out of 43 vaccinated animals in the G herd were each infected with two A. marginale strains carrying two distinct genotypes; in this herd the follow-up during years 2003-2007 demonstrated that several animals carried different msp1a genotypes at different time points. Coinfection with two different genotypes of A. marginale in A. centrale vaccinated cattle was observed in another herd, as well. It appears that A. marginale is composed of a heterogeneous changing bacterial population that evolves in the host or, the genotypic diversity implies high transmission intensity by the vector, or both. Learning how this diversity is generated and identification of distinct A. marginale strains coupled with high sequence variation of MSP1a will aid in understanding Anaplasma transmission and disease development.
本研究旨在证明在无浆体病流行地区放牧的感染肉牛群中边缘无浆体的基因多样性。在不同牛群之间、每个牛群内部以及单个动物体内均鉴定出了基因多样性。以色列菌株显示出MSP1a重复序列的独特特征，除了已公布的重复序列外，还鉴定出了六个新的串联重复序列，命名为Is1 - 5和Is9。检测到个体接种中央无浆体疫苗的动物被两种基因不同的边缘无浆体菌株双重感染。G牛群中43头接种疫苗的动物中有6头分别感染了携带两种不同基因型的两种边缘无浆体菌株；在该牛群中，2003 - 2007年的随访表明，几只动物在不同时间点携带不同的msp1a基因型。在另一个牛群中也观察到接种中央无浆体疫苗的牛被两种不同基因型的边缘无浆体双重感染。边缘无浆体似乎由在宿主体内进化的异质变化细菌群体组成，或者基因多样性意味着媒介的高传播强度，或者两者兼而有之。了解这种多样性是如何产生的以及鉴定不同的边缘无浆体菌株并结合MSP1a的高序列变异将有助于理解无浆体的传播和疾病发展。
