Department of Epidemiology, China and Key Laboratory of Public Health Safety (Fudan University), School of Public Health, Fudan University, Ministry of Education, Shanghai 200032, China.
Department of Public Health Sciences, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Int J Environ Res Public Health. 2018 Apr 17;15(4):782. doi: 10.3390/ijerph15040782.
This study aimed to validate the epidemiological significance and temporal stability of Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) typing in a genetically and geographically diverse set of clinical isolates from patients diagnosed with pulmonary tuberculosis in China. Between 2010 and 2013, a total of 982 isolates were collected from four population-based investigations in China. Apart from the currently applied 24-locus MIRU-VNTR, six additional hypervariable loci were analyzed in order to validate the MIRU-VNTR combinations in terms of their epidemiological links, clustering time span, and paired geographic distance. In vitro temporal stability was analyzed for both individual MIRU-VNTR loci, and for several combinations of loci. In the present study, four MIRU-VNTR combinations, including the hypervariable loci 3820, 3232, 2163a, and 4120, were evaluated. All of these combinations obtained a Hunter-Gaston discriminatory index (HGDI) value over 0.9900 with a reduced clustering proportion (from 32.0% to 25.6%). By comparing epidemiological links, clustering time span, and paired geographic distance, we found that the performances of the four MIRU-VNTR combinations were comparable to the insertion sequence 6110 restriction fragment length polymorphism (IS-RFLP), and significantly better than that of 24-locus MIRU-VNTR genotyping alone. The proportion of temporally stable loci ranged from 90.5% to 92.5% within the combined MIRU-VNTR genotyping, which is higher than IS-RFLP (85.4%). By adding four hypervariable loci to the standard 24-locus MIRU-VNTR genotyping, we obtained a high discriminatory power, stability and epidemiological significance. This algorithm could therefore be used to improve tuberculosis transmission surveillance and outbreak investigation in China.
本研究旨在验证分枝杆菌散布重复单位-可变数目串联重复（MIRU-VNTR）分型在我国确诊肺结核患者的基因和地理多样化临床分离株中的流行病学意义和时间稳定性。2010 年至 2013 年，从中国的四项基于人群的调查中总共收集了 982 株分离株。除了目前应用的 24 位 MIRU-VNTR 之外，还分析了六个额外的高变区位点，以验证 MIRU-VNTR 组合在其流行病学联系、聚类时间跨度和配对地理距离方面的稳定性。分析了单个 MIRU-VNTR 基因座以及多个基因座组合的体外时间稳定性。在本研究中，评估了四个 MIRU-VNTR 组合，包括高变区位点 3820、3232、2163a 和 4120。所有这些组合的 Hunter-Gaston 区分指数（HGDI）值均超过 0.9900，聚类比例降低（从 32.0%降至 25.6%）。通过比较流行病学联系、聚类时间跨度和配对地理距离，我们发现这四个 MIRU-VNTR 组合的性能与插入序列 6110 限制片段长度多态性（IS-RFLP）相当，明显优于单独的 24 位 MIRU-VNTR 基因分型。在联合 MIRU-VNTR 基因分型中，时间稳定基因座的比例范围为 90.5%至 92.5%，高于 IS-RFLP（85.4%）。通过向标准的 24 位 MIRU-VNTR 基因分型中添加四个高变区位点，我们获得了高的分辨力、稳定性和流行病学意义。因此，该算法可用于改善中国的结核病传播监测和暴发调查。
