Groupings of highly similar major surface protein (p44)-encoding paralogues:: a potential index of genetic diversity amongst isolates of Anaplasma phagocytophilum
Groupings of highly similar major surface protein (p44)-encoding paralogues:: a potential index of genetic diversity amongst isolates of Anaplasma phagocytophilum
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DOI：
10.1099/mic.0.26648-0
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发表时间：
2004-03-01
期刊：
影响因子：
2.8
通讯作者：
Ogden, NH
中科院分区：
文献类型：
--
作者：
Casey, ANJ;Birtles, RJ;Ogden, NH
嗜吞噬细胞无形体是一种蜱传播的细菌，在美国和南欧是人畜共患病，但尽管该细菌在英国是地方性的，但在该国尚未发现临床人类疾病病例。英国和美国分离株之间的潜在基因组差异进行了研究，通过比较部分16 S rRNA基因和p44基因片段序列PCR扩增10英国反刍动物或蜱分离株，与美国分离株公布的序列。通过16 S rRNA基因序列比对的系统发育分析，分离株之间没有显著的聚类。从英国分离株获得的81个克隆扩增的p44旁系同源物编码的预测蛋白质的结构与先前描述的来自美国分离株的旁系同源物的结构相似。旁系同源序列没有明显的国家，宿主物种或分离物的聚类，但大多数旁系同源物是30-70%的相似性，使有意义的比对困难。来自不同分离株的一些p44旁系同源物形成了彼此相似度超过90%的序列簇（“相似性组”）。每个簇中的旁系同源物在最可能编码配体的基因区域特别相似。在所研究的样本中，95%的相似性组仅包括来自美国或英国分离株的旁系同源物，并且在来自美国而不是英国分离株的旁系同源物中发生的频率更高。这些发现提出了一个假设，即相似组中的旁系同源物序列可能提供了不同A“株”适应的指标。嗜吞噬细胞菌对不同地理位置的特定储存宿主的感染性，以及与包括人类在内的不同物种的感染性的任何关联。
Anaplasma phagocytophilum is a tick-borne bacterium that is zoonotic in the USA and southern Europe, but although the bacterium is endemic in the UK, no cases of clinical human disease have yet been detected in that country. Potential genomic differences amongst UK and USA isolates were investigated by comparing partial 16S rRNA gene and p44 paralogue sequences amplified by PCR from 10 UK ruminant or tick isolates, with published sequences from USA isolates. No significant clustering among the isolates was resolved by phylogenetic analysis of alignments containing 16S rRNA gene sequences. The structure of predicted proteins encoded by p44 paralogues, amplified from 81 clones obtained from the UK isolates, was similar to that described previously for paralogues from USA isolates. Paralogue sequences did not obviously cluster by country, host species or isolate, but most paralogues were 30-70% similar, making meaningful alignments difficult. Some p44 paralogues from different isolates formed clusters of sequences that were more than 90% similar to one another ('similarity groups'). The paralogues in each cluster were particularly similar in gene regions most likely to code for ligands. In the sample studied, 95% of the similarity groups comprised paralogues from either USA or UK isolates only and occurred with greater frequency amongst paralogues from USA rather than UK isolates. These findings raise the hypothesis that sequences of paralogues in similarity groups may provide an index of adaptation of different 'strains' of A. phagocytophilum to specific reservoir hosts in different geographical locations, and any associations with infectivity for different species including humans.