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Inducing Meningococcal Meningitis Serogroup C in Mice via Intracisternal Delivery
Published on: November 5, 2019
Genetic basis of meningococcal capsular switching between serogroups A and B belonging to ST-7
Xueping Liu1, Hairui Wang1, Li Xu1
1National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention & Chinese Academy of Preventive Medicine, Beijing, China.
Objectives:
Capsular switching from serogroup A to serogroups C or X has been documented, whereas it is rarely observed from serogroup A to serogroup B. This study aims to report and characterize a rare capsular switching event from serogroup A to serogroup B belonging to ST-7.
Methods:
Comparative genomic analyses were performed on ST-7 isolates across serogroups A, B, C, and X. Recombination analysis of the cps locus was conducted to determine the recombination boundaries. The fitness costs of capsular switching were assessed by comparing bacterial growth assay, adhesion and invasive capacities of capsular switching strains.
Results:
Phylogenetic and average nucleotide identity (ANI > 99.9%) analysis suggested that the serogroup A strain probably represents their common progenitor. Recombination analysis of the cps locus indicated that the upstream recombination breakpoints were at ctrE, rfbB, and galE, while ctrC served as the downstream recombination boundary. Pathogenicity analysis showed that four serogroup isolates exhibited different growth rates during the exponential phase. The serogroup A isolate exhibited significantly greater capacities of adhesion and invasion.
Conclusion:
This study reveals the occurrence of capsular switching from serogroup A to serogroup B in N. meningitidis, which facilitates immune evasion yet incurs fitness cost.
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