Centre for Clinical Microbiology, Division of Infection and Immunity, University College London, London, UK.
Institute of Infection and Immunity, St George's, University of London, London, UK.
Microb Genom. 2023 Aug;9(8). doi: 10.1099/mgen.0.001077.
The bacillus Calmette-Guérin (BCG) vaccine has been in use for prevention of tuberculosis for over a century. It remains the only widely available tuberculosis vaccine and its protective efficacy has varied across geographical regions. Since it was developed, the BCG vaccine strain has been shared across different laboratories around the world, where use of differing culture methods has resulted in genetically distinct strains over time. Whilst differing BCG vaccine efficacy around the world is well documented, and the reasons for this may be multifactorial, it has been hypothesized that genetic differences in BCG vaccine strains contribute to this variation. Isolates from an historic archive of lyophilized BCG strains were regrown, DNA was extracted and then whole-genome sequenced using Oxford Nanopore Technologies. The resulting whole-genome data were plotted on a phylogenetic tree and analysed to identify the presence or absence of regions of difference (RDs) and single-nucleotide polymorphisms (SNPs) relating to virulence, growth and cell wall structure. Of 50 strains available, 36 were revived in culture and 39 were sequenced. Morphology differed between the strains distributed before and after 1934. There was phylogenetic association amongst certain geographically classified strains, most notably BCG-Russia, BCG-Japan and BCG-Danish. RD2, RD171 and RD713 deletions were associated with late strains (seeded after 1927). When mapped to BCG-Pasteur 1172, the SNPs in , , and were associated with early strains. Whilst BCG-Russia, BCG-Japan and BCG-Danish showed strong geographical isolate clustering, the late strains, including BCG-Pasteur, showed more variation. A wide range of SNPs were seen within geographically classified strains, and as much intra-strain variation as between-strain variation was seen. The date of distribution from the original Pasteur laboratory (early pre-1927 or late post-1927) gave the strongest association with genetic differences in regions of difference and virulence-related SNPs, which agrees with the previous literature.
卡介苗（BCG）疫苗已被用于预防结核病超过一个世纪。它仍然是唯一广泛可用的结核病疫苗，其保护效果在不同地区有所不同。自开发以来，BCG 疫苗株已在世界各地的不同实验室共享，随着时间的推移，使用不同的培养方法导致了遗传上不同的菌株。虽然世界各地的 BCG 疫苗效果不同已有充分记录，并且原因可能是多方面的，但有人假设 BCG 疫苗株的遗传差异导致了这种差异。从冻干 BCG 菌株的历史档案中分离出的菌株被重新生长，提取 DNA，然后使用牛津纳米孔技术进行全基因组测序。将得到的全基因组数据绘制在系统发育树上，并进行分析以确定与毒力、生长和细胞壁结构相关的差异区（RD）和单核苷酸多态性（SNP）的存在或缺失。在可用的 50 株菌株中，有 36 株在培养中复活，有 39 株进行了测序。菌株之间的形态学差异分布在 1934 年之前和之后。某些按地理位置分类的菌株之间存在系统发育关联，最显著的是 BCG-俄罗斯、BCG-日本和 BCG-丹麦。RD2、RD171 和 RD713 缺失与后期菌株（1927 年后播种）相关。当映射到 BCG-Pasteur 1172 时， 、 、 和 中的 SNPs 与早期菌株相关。虽然 BCG-俄罗斯、BCG-日本和 BCG-丹麦显示出强烈的地理分离聚类，但包括 BCG-Pasteur 在内的后期菌株显示出更多的变异。在按地理位置分类的菌株中观察到广泛的 SNPs，并且在菌株内变异与菌株间变异一样多。从原始巴斯德实验室分发的日期（1927 年之前的早期或 1927 年之后的晚期）与 RD 和与毒力相关的 SNPs 的差异区域中的遗传差异最强相关，这与之前的文献一致。
