title: Genetic and antigenic analysis of invasive serogroup C Neisseria meningitidis in Canada: A decrease in the electrophoretic type (ET)-15 clonal type and an increase in the proportion of isolates belonging to the ET-37 (but not ET-15) clonal type during the period from 2002 to 2009.
abstract: BACKGROUND
  Serogroup C meningococcal disease has been endemic in Canada since the early 1990s, with periods of hyperendemic disease documented in the past two decades. The present study characterized invasive serogroup C meningococci in Canada during the period from 2002 to 2009.
  
  
  METHODS
  Serogroup C meningococci were serotyped using monoclonal antibodies. Their clonal types were identified by either multilocus enzyme electrophoresis or multilocus sequence typing.
  
  
  RESULTS
  The number of invasive serogroup C Neisseria meningitidis isolates received at the National Microbiology Laboratory (Winnipeg, Manitoba) for characterization has dropped from a high of 173 isolates in 2001 to just 17 in 2009, possibly related to the introduction of the serogroup C meningococcal conjugate vaccine. Before 2006, 80% to 95% of all invasive serogroup C meningococci belonged to the electrophoreic type (ET)-15 clonal type, and the ET-37 (but not ET-15) type only accounted for up to 5% of all isolates. However, beginning in 2006, the percentage of the ET-15 clonal type decreased while the ET-37 (but not ET-15) type increased from 27% in 2006 to 52% in 2009. The percentage of invasive serogroup C isolates not belonging to either ET-15 or ET-37 also increased. Most ET-15 isolates expressed the antigenic formula of C:2a:P1.7,1 or C:2a:P1.5. In contrast, the ET-37 (but not ET-15) isolates mostly expressed the antigens of C:2a:P1.5,2 or C:2a:P1.2.
  
  
  CONCLUSIONS
  A shift in the antigenic and clonal type of invasive serogroup C meningococi was noted. This finding suggests vigilance in the surveillance of meningoccocal disease is warranted.
authors.affiliation: Public Health Agency of Canada, Winnipeg, Manitoba;
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zhou
authors.forename: Frances
authors.initials: F
authors.lastname: Jamieson
authors.forename: Sharon
authors.initials: S
authors.lastname: Dolman
authors.forename: Linda Mn
authors.initials: LM
authors.lastname: Hoang
authors.forename: Prasad
authors.initials: P
authors.lastname: Rawte
authors.forename: Raymond Sw
authors.initials: RS
authors.lastname: Tsang
keywords: ET-15; ET-37; Meningococci; Serogroup C