Streit Elisabeth, Millet Julie, Rastogi Nalin
WHO Supranational TB Reference Laboratory, TB & Mycobacteria Unit, Institut Pasteur de la Guadeloupe, F97183 Abymes, Guadeloupe.
WHO Supranational TB Reference Laboratory, TB & Mycobacteria Unit, Institut Pasteur de la Guadeloupe, F97183 Abymes, Guadeloupe.
Int J Mycobacteriol. 2015 Sep;4(3):222-7. doi: 10.1016/j.ijmyco.2015.05.005. Epub 2015 Jun 3.
The advent of molecular typing using MIRU-VNTR mini-satellites has largely facilitated tuberculosis (TB) molecular epidemiological studies. Apart from detecting the chains of transmission and risk factors, these markers have also allowed to study the phenomena of mixed strain infections versus microevolutionary events.
An initial set of Mycobacterium tuberculosis strains (n=161) genotyped using spoligotyping and MIRU-VNTRs in Guyana and Suriname was evaluated for indications mixed strain infections (characterized by the detection of double alleles in 2 or more MIRU loci) versus "in-patient" microevolutionary events (characterized by the detection of double alleles in a single locus).
The present study hereby reports evidence of microevolution in 3.7% (n=6/161) of the studied population, vs. 0.6% (n=1/161) for mixed infection. The strains belonged to three different spoligotyping-based lineages, namely the T (SITs 44, 53, and 1081), Haarlem (SIT47), and EAI (SITs 72 and 349) lineages, while 1 isolate (SIT237) could not be assigned to any lineage.
By comparing these results on microevolutionary cases (n=6) to 112,000 strains present in the SITVIT2 database, evidence is presented that in 2/6 cases (each case corresponding to 2 patterns due to MIRU double bands), one of the patterns corresponded to a shared type found exclusively in Suriname or Guyana. Phylogenetic analysis showed that no spoligotyping lineage in particular was more prone to microevolutionary events in this study's sample. Overall, the observations fortify the awareness regarding the existence of microevolution and polyclonal TB infections which has important implications for patient care.
使用MIRU-VNTR微型卫星进行分子分型的出现极大地促进了结核病（TB）分子流行病学研究。除了检测传播链和风险因素外，这些标记还使得研究混合菌株感染现象与微观进化事件成为可能。
对在圭亚那和苏里南使用间隔寡核苷酸分型（spoligotyping）和MIRU-VNTR对一组初始结核分枝杆菌菌株（n = 161）进行基因分型，以评估混合菌株感染（以在2个或更多MIRU位点检测到双等位基因为特征）与“住院患者”微观进化事件（以在单个位点检测到双等位基因为特征）的迹象。
本研究特此报告在所研究人群中有3.7%（n = 6/161）存在微观进化的证据，而混合感染为0.6%（n = 1/161）。这些菌株属于三个不同的基于间隔寡核苷酸分型的谱系，即T（国际标准型44、53和1081）、哈勒姆（国际标准型47）和EAI（国际标准型72和349）谱系，而1株分离株（国际标准型237）无法归入任何谱系。
通过将这些微观进化病例（n = 6）的结果与SITVIT2数据库中存在的112,000株菌株进行比较，有证据表明在2/6的病例中（由于MIRU双条带，每个病例对应2种模式），其中一种模式对应于仅在苏里南或圭亚那发现的共享类型。系统发育分析表明，在本研究样本中，没有特定的间隔寡核苷酸分型谱系更容易发生微观进化事件。总体而言，这些观察结果强化了对微观进化和多克隆结核病感染存在的认识，这对患者护理具有重要意义。
