Comparison of invasive and non-invasive isolates of Neisseria meningitidis by whole genome sequencing, Czech Republic, 2005-2021.

Aim: Whole genome sequencing (WGS) analysis of candidate virulence genes of epidemiologically and/or clinically related invasive and non-invasive isolates of Neisseria meningitidis from 2005-2021.

Material and methods: Seventy-nine isolates were selected for analysis from three different categories: cases of invasive meningococcal disease (IMD) and their healthy contacts, different clinical specimens from the same IMD case, and different clinical specimens from the same IMD case and their healthy contacts. WGS was used to analyse sequence variability in candidate N. meningitidis virulence factor genes, with more than 250 loci studied.

Results: The frequency of sequence changes in the candidate N. meningitidis virulence factor genes of invasive and non-invasive isolates varied widely. The highest level of variability was observed in the pilus genes, especially pilE and pglA. Our study detected variability in the opacity protein A (opaA) gene in more than half of the isolates analysed, with the frequency of opaA gene changes reaching almost 70% in MenC isolates. Higher frequency of changes were also observed in the genes for capsule production, especially in those of the D+D' capsular region.

Conclusions: The results obtained support the hypothesis that serogroup-specific genetic mechanisms are also involved in the pathogenicity of N. meningitidis. These data add to the body of knowledge necessary for the development of new effective IMD vaccines.