Genome-Based Characterization of Emergent Invasive Neisseria meningitidis Serogroup Y Isolates in Sweden from 1995 to 2012

Abstract

Invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup Y has increased in Europe, especially in Scandinavia. In Sweden, serogroup Y is now the dominating serogroup, and in 2012, the serogroup Y disease incidence was 0.46/100,000 population. We previously showed that a strain type belonging to sequence type 23 was responsible for the increased prevalence of this serogroup in Sweden. The objective of this study was to investigate the serogroup Y emergence by whole-genome sequencing and compare the meningococcal population structure of Swedish invasive serogroup Y strains to those of other countries with different IMD incidence. Whole-genome sequencing was performed on invasive serogroup Y isolates from 1995 to 2012 in Sweden (n = 186). These isolates were compared to a collection of serogroup Y isolates from England, Wales, and Northern Ireland from 2010 to 2012 (n = 143), which had relatively low serogroup Y incidence, and two isolates obtained in 1999 in the United States, where serogroup Y remains one of the major causes of IMD. The meningococcal population structures were similar in the investigated regions; however, different strain types were prevalent in each geographic region. A number of genes known or hypothesized to have an impact on meningococcal virulence were shown to be associated with different strain types and subtypes. The reasons for the IMD increase are multifactorial and are influenced by increased virulence, host adaptive immunity, and transmission. Future genome-wide association studies are needed to reveal additional genes associated with serogroup Y meningococcal disease, and this work would benefit from a complete serogroup Y meningococcal reference genome.

Serogroup and Clonal Characterization of Czech Invasive Neisseria meningitidis Strains Isolated from 1971 to 2015

“…meningitidis Y cc23 have been reported since 1995 and account for 51% of all isolates of this serogroup. Similar increasing trends were observed in other European countries such as Sweden [30] and the UK [6] or in the USA [31]. IMD cases caused by N .…”

Difference in virulence between Neisseria meningitidis serogroups W and Y in transgenic mice

“…meningitidis serogroups W (NmW) and Y (NmY) are currently the major serogroups causing IMD in Sweden, with incidences (and proportions) of 0.22 (44%) and 0.12 (22%) per 100,000 population respectively in 2018. The incidence of NmY has been high in Sweden since 2005, with the increase due to the YI strain of cc23 [8][9][10]. YI consists of two genetically distinct subtypes, one of which (subtype 1) has been determined as the cause of the increased incidence [9].…”

“…The incidence of NmY has been high in Sweden since 2005, with the increase due to the YI strain of cc23 [8][9][10]. YI consists of two genetically distinct subtypes, one of which (subtype 1) has been determined as the cause of the increased incidence [9]. An increase in NmY has also been reported from other European countries [11].…”

“…The genetic differences within YI cc23 and the South American/UK sub-lineage of cc11 are few, and cannot explain the observed difference in incidence of the subtypes or strains in these serogroups [9,12]. However, the impact of these differences on the bacterial virulence has not been explored experimentally.…”

Neisseria meningitidis carriage in Swedish teenagers associated with the serogroup W outbreak at the World Scout Jamboree, Japan 2015

“…In Sweden, a striking increase in NmW was seen in 2015, from rarely causing IMD, generally only a few cases per year, range 0–5 since 1990 onwards, to unexpectedly causing more than twice as many cases in 2015 (n = 10). This during a time period when the overall incidence of Nm has been rather stable in Sweden, except for an increase in the total number during 2009–2013, but this increase was mainly due to an increase in NmY disease . This increasing trend of NmW seen in the low endemic country Sweden, 2015, has also been observed in several other European countries such as England and Wales, France, Finland and the Netherlands as well as in Australia in the last couple of years and the trend seems to continue at least in Sweden (2016; n = 18) .…”