Larsson Pär, Svensson Kerstin, Karlsson Linda, Guala Dimitri, Granberg Malin, Forsman Mats, Johanssont Anders
Swedish Defence Research Agency, Umeå, Sweden.
Emerg Infect Dis. 2007 Nov;13(11):1725-32. doi: 10.3201/eid1311.070603.
To develop effective and accurate typing of strains of Francisella tularensis, a potent human pathogen and a putative bioterrorist agent, we combined analysis of insertion-deletion (indel) markers with multiple-locus variable-number tandem repeat analysis (MLVA). From 5 representative F. tularensis genome sequences, 38 indel markers with canonical properties, i.e., capable of sorting strains into major genetic groups, were selected. To avoid markers with a propensity for homoplasy, we used only those indels with 2 allelic variants and devoid of substantial sequence repeats. MLVA included sequences with much diversity in copy number of tandem repeats. The combined procedure allowed subspecies division, delineation of clades A.I and A.II of subspecies tularensis, differentiation of Japanese strains from other strains of subspecies holarctica, and high-resolution strain typing. The procedure uses limited amounts of killed bacterial preparations and, because only 1 single analytic method is needed, is time- and cost-effective.
为了开发有效且准确的土拉弗朗西斯菌菌株分型方法，土拉弗朗西斯菌是一种强大的人类病原体及潜在的生物恐怖主义制剂，我们将插入缺失（indel）标记分析与多位点可变数目串联重复序列分析（MLVA）相结合。从5个具有代表性的土拉弗朗西斯菌基因组序列中，选择了38个具有典型特征的indel标记，即能够将菌株分类到主要遗传组中。为了避免具有平行进化倾向的标记，我们仅使用那些具有2个等位基因变体且无大量序列重复的indel。MLVA包括串联重复序列拷贝数具有很大多样性的序列。这种联合方法能够进行亚种划分，区分土拉弗朗西斯菌亚种的A.I和A.II分支，区分日本菌株与全北区亚种的其他菌株，并实现高分辨率菌株分型。该方法使用少量的灭活细菌制剂，并且由于仅需要一种单一分析方法，因此具有时间和成本效益。
