Molad T, Fleiderovitz L, Leibovich B, Wolkomirsky R, Erster O, Roth A, Mazuz M L, Markovics A, Shkap V
Division of Parasitology, Kimron Veterinary Institute, P.O. Box 12, Bet Dagan 50250, Israel.
Division of Parasitology, Kimron Veterinary Institute, P.O. Box 12, Bet Dagan 50250, Israel.
Vet Parasitol. 2014 Sep 15;205(1-2):20-7. doi: 10.1016/j.vetpar.2014.07.016. Epub 2014 Jul 24.
This study demonstrated the genetic diversity among MSA-2c, MSA-2a1 and MSA-2b proteins of Babesia bovis isolates obtained from bovine blood and Rhipicephalus annulatus tick samples. The least identities that were observed among the deduced amino acid sequences of MSA-2c, MSA-2a1 and MSA-2b were 55, 63, and 71%, respectively. During the study four B. bovis calves, aged about 1 month, were found to be infected with virulent field strains and developed babesiosis. Probably, the calves had received insufficient antibodies, or the antibodies raised against the vaccine strain did not cross-protect against virulent field isolates. The complete msa-2 locus from the Israeli B. bovis vaccine strain and two field isolates were characterized. Similarly to the Australian strains and isolates, the msa-2 loci of the examined Israeli strain and isolates had only two msa-2 genes - msa-2c and msa-2a/b - located between msa-2c and orfB. Several of the examined samples, contained different MSA-2 genotypes concurrently. No obvious geographical relationships among isolates from various regions of Israel were established. Moreover, in the phylogenetic analyses, the Israeli deduced MSA-2 amino acid sequences of the three examined genes were clustered together with sequences derived from other countries, proving that the msa-2 gene sequences of B. bovis shared the same genetic characters worldwide. The present study clearly showed that the MSA-2 proteins of B. bovis isolates from Israel were genetically distinct from the vaccine strains. Thus, further research will be needed in order to understand the genetic diversity mechanisms of B. bovis, and the immunological responses of the infected animals.
本研究展示了从牛血液和微小牛蜱样本中获得的牛巴贝斯虫分离株的MSA-2c、MSA-2a1和MSA-2b蛋白之间的遗传多样性。在MSA-2c、MSA-2a1和MSA-2b的推导氨基酸序列中观察到的最低同源性分别为55%、63%和71%。在研究过程中，发现4头约1月龄的牛巴贝斯虫感染牛犊感染了强毒野外菌株并患上了巴贝斯虫病。可能这些牛犊获得的抗体不足，或者针对疫苗株产生的抗体不能交叉保护抵御强毒野外分离株。对以色列牛巴贝斯虫疫苗株和两个野外分离株的完整msa-2基因座进行了表征。与澳大利亚菌株和分离株类似，所检测的以色列菌株和分离株的msa-2基因座只有两个msa-2基因——msa-2c和msa-2a/b——位于msa-2c和orfB之间。一些检测样本同时包含不同的MSA-2基因型。未在以色列不同地区的分离株之间建立明显的地理关系。此外，在系统发育分析中，所检测的三个基因的以色列推导MSA-2氨基酸序列与来自其他国家的序列聚集在一起，证明牛巴贝斯虫的msa-2基因序列在全球具有相同的遗传特征。本研究清楚地表明，来自以色列的牛巴贝斯虫分离株的MSA-2蛋白在遗传上与疫苗株不同。因此，需要进一步研究以了解牛巴贝斯虫的遗传多样性机制以及受感染动物的免疫反应。
