Genetic and antigenic characterization of invasive endemic serogroup B Neisseria meningitidis from Ontario, Canada, in 2001-2010.

This study examined the antigenic and genetic diversity of serogroup B Neisseria meningitidis (MenB) recovered from invasive meningococcal disease (IMD) cases in Ontario, Canada, over the period 2001-2010 during which no MenB outbreaks had occurred. MenB was found to be responsible for 39% of all IMD cases, with the remaining cases caused mainly by serogroups Y (28%), C (23.5%) and W135 (8%). One hundred and ninety-three individual MenB case isolates were collected and characterized. Of the 88 sequence types (STs) identified, 75 were grouped into 14 known clonal complexes (CCs), whilst 13 STs were not assigned to any known CC. Fifty-seven different PorA genotypes and 88 STs defined the diversity of invasive MenB in Ontario, which supported the endemic nature of MenB disease in Ontario. Despite the presence of the hypervirulent ST-41/44 and ST-32 CCs, no single ST was predominant and responsible for a large number of IMD cases. Although the Quebec outbreak clone of ST-269 was also found in Ontario, the 20 case isolates were genetically diverse: they grouped into seven STs and did not have a predominant PorA genotype. eBuRs-r analysis identified a new CC responsible for 14.5% of the MenB case isolates. The six most common PorA variable region 2 (VR2) genotypes (VR2-9, -4, -14, -16, -13-1 and -16-3) were found in 67% of invasive MenB isolates.