Arvand Mardjan, Schubert Hannah, Viezens Juliane
Institut für Medizinische Mikrobiologie, Virologie und Hygiene, Universität Rostock, Schillingallee 70, D-18057 Rostock, Germany.
Microbes Infect. 2006 Apr;8(5):1315-20. doi: 10.1016/j.micinf.2005.12.015. Epub 2006 Mar 15.
Bartonella henselae isolates from different hosts display a marked genetic heterogeneity, as determined by pulsed-field gel electrophoresis (PFGE). The aim of the present study was to determine whether different genetic variants may coexist within the population of distinct B. henselae isolates and could be detected by PFGE. Three primary B. henselae isolates and the B. henselae reference strains ATCC 49793 and 49882 were subjected as single colony derived cultures in quadruplicate to PFGE analysis upon restriction with SmaI or NotI. Up to 4 fragment differences were found among the cultures obtained from each primary isolate, indicating the coexistence of genetic variants in the population of primary B. henselae isolates. The clonal relatedness of the genetic variants was confirmed by arbitrarily primed PCR and multi-locus sequence typing. In contrast to the primary isolates, no variants were detected among the single colony derived cultures of the high-passage ATCC strains. We hypothesized that the coexistence of different genetic variants may represent a feature that is restricted to primary or low-passage B. henselae isolates. The primary isolates were serially passed in vitro and then subjected as single colony derived cultures to PFGE analysis, which now revealed identical patterns among the quadruplicate cultures of each high-passage isolate. These results suggest that the population of a primary B. henselae isolate is composed of distinct genetic variants, which may disappear upon repeated passages on artificial culture media. Generation of genetic variants by B. henselae may represent an escape mechanism to circumvent the host specific immune responses.
通过脉冲场凝胶电泳（PFGE）测定发现，来自不同宿主的汉赛巴尔通体分离株表现出明显的遗传异质性。本研究的目的是确定不同的遗传变异体是否可能共存于不同的汉赛巴尔通体分离株群体中，并能否通过PFGE检测到。将三株原发性汉赛巴尔通体分离株以及汉赛巴尔通体参考菌株ATCC 49793和49882作为单菌落衍生培养物一式四份，用SmaI或NotI酶切后进行PFGE分析。在从每个原发性分离株获得的培养物中发现了多达4个片段差异，表明原发性汉赛巴尔通体分离株群体中存在遗传变异体共存的情况。通过任意引物PCR和多位点序列分型证实了遗传变异体的克隆相关性。与原发性分离株不同，在高传代ATCC菌株的单菌落衍生培养物中未检测到变异体。我们推测不同遗传变异体的共存可能是原发性或低传代汉赛巴尔通体分离株所特有的特征。将原发性分离株在体外连续传代，然后作为单菌落衍生培养物进行PFGE分析，结果显示每个高传代分离株的一式四份培养物之间具有相同的图谱。这些结果表明，原发性汉赛巴尔通体分离株群体由不同的遗传变异体组成，这些变异体在人工培养基上反复传代后可能会消失。汉赛巴尔通体产生遗传变异体可能是一种逃避机制，以规避宿主特异性免疫反应。
