Zhu Bingqing, Yao Pingping, Zhang Leyi, Gao Yuan, Xu Li, Xie Na, Shao Zhujun
State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China.
Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, People's Republic of China.
Infect Immun. 2017 May 23;85(6). doi: 10.1128/IAI.01019-16. Print 2017 Jun.
causes meningococcal disease, often resulting in fulminant meningitis, sepsis, and death. Vaccination programs have been developed to prevent infection of this pathogen, but serogroup replacement is a problem. Capsular switching has been an important survival mechanism for , allowing the organism to evolve in the present vaccine era. However, related mechanisms have not been completely elucidated. Genetic analysis of capsular switching between diverse serogroups would help further our understanding of this pathogen. In this study, we analyzed the genetic characteristics of the sequence type 7 (ST-7) serogroup X strain that was predicted to arise from ST-7 serogroup A at the genomic level. By comparing the genomic structures and sequences, ST-7 serogroup X was closest to ST-7 serogroup A, whereas eight probable recombination regions, including the capsular gene locus, were identified. This indicated that serogroup X originated from serogroup A by recombination leading to capsular switching. The recombination involved approximately 8,540 bp from the end of the gene to the middle of the gene. There were more recombination regions and strain-specific single-nucleotide polymorphisms in serogroup X than in serogroup A genomes. However, no specific gene was found for each serogroup except those in the capsule gene locus.
可引发脑膜炎球菌病，常导致暴发性脑膜炎、败血症及死亡。已制定疫苗接种计划以预防该病原体感染，但血清群替换是个问题。荚膜转换一直是该菌重要的生存机制，使其能在当前疫苗时代进化。然而，相关机制尚未完全阐明。对不同血清群间荚膜转换进行基因分析将有助于我们进一步了解这种病原体。在本研究中，我们在基因组水平分析了预测由ST-7血清群A产生的序列型7（ST-7）血清群X菌株的遗传特征。通过比较基因组结构和序列，ST-7血清群X与ST-7血清群A最为接近，同时鉴定出包括荚膜基因座在内的8个可能的重组区域。这表明血清群X通过导致荚膜转换的重组起源于血清群A。重组涉及从基因末端到基因中部约8540 bp的区域。血清群X的重组区域和菌株特异性单核苷酸多态性比血清群A基因组更多。然而，除了荚膜基因座中的基因外，未发现每个血清群的特异性基因。
