Genomic epidemiology of Neisseria meningitidis serogroup W in Switzerland between 2010 and 2016

Genomic surveillance of Neisseria meningitidis serogroup W in Portugal from 2003 to 2019

In recent years, a change in the epidemiology of meningococcal disease caused by Neisseria meningitidis serogroup W (MenW) has been observed worldwide, with the emergence of new sublineages associated with a higher rate of fatal cases. The present study intends to describe the epidemiology of invasive meningococcal disease (IMD) due to MenW in Portugal between 2003 and 2019, and to genetically characterize population structure. Despite MenW has a low incidence in Portugal, having almost disappeared from 2008 to 2015, since 2016, the number of MenW cases has been steadily increasing at a rate of ~ twofold per year, with more than 80% of the characterized isolates belonging to clonal complex 11 (cc11). Core-genome phylogeny of 25 Portuguese (PT) MenW isolates showed a strain clustering mainly either with the Original UK or the UK 2013 sublineages. Our study also reported for the first time the presence of distinct prophages with a notable overrepresentation of an ~ 32-35-kb PS_1-like prophage found in MenW cc11 genomes. The presence of the PS_1-like prophage in almost all 4723 cc11 genomes selected from Neisseria PubMLST database regardless of the capsular group they belong to suggests an ancestral acquisition of this mobile element prior to capsular switching events. Overall, by mimicking the scenario observed worldwide, this study reinforces the importance of a close monitoring of MenW disease, especially from cc11, in order to promptly adapt the vaccination plan for IMD control in Portugal. Moreover, future studies are needed to understand the putative contribution of prophages to fitness and virulence of PT MenW strains.

Strain coverage of Bexsero vaccine assessed by whole-genome sequencing over a cohort of invasive meningococci of serogroups B and W isolated in Switzerland

Invasive meningococcal disease (IMD), caused by Neisseria meningitidis (Nm) strains, is a life-threatening but vaccine-preventable condition. Bexsero is a four-component vaccine that offers broad protection against Nm of serogroup B (NmB), particularly common in Europe. In Switzerland, Bexsero has not yet been licensed and no information is available concerning the predicted vaccine coverage on isolates of circulating Nm. We performed genotyping of Bexsero antigen loci by whole-genome sequencing (WGS) on 104 NmB collected in Switzerland in the 2010-2015 period. We searched for antigen variants previously defined as predictors of strain coverage and estimated that 50% of IMD NmB strains were potentially covered by the vaccine. Clonal complexes (cc) 32, 41/44 and 269, considered the best covered lineages, were further sub-typed according to Bexsero Antigen Sequence Type (BAST) scheme. We also genotyped by WGS 40 Nm of serogroup W (NmW) collected in the country between 2010 and 2016. NmW cc22 isolates appeared to be covered by the vaccine, which was not the case for cc11 isolates, whose incidence has recently increased in Switzerland and all over Europe. Our work underlines the benefit of using WGS for surveillance of vaccine antigen variant distribution in local Nm population and taking proper measures to prevent the spread of NmB.