Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2016

Transcontinental changes in the population structure of Neisseria meningitidis and coverage of the BEXSERO® vaccine in Western Australia and Victoria (#47)

Shakeel Mowlaboccus 1 , Timothy T Perkins 1 , Helen Smith 2 , Theo Sloots 3 , Sarah Tozer 3 , Lydia-Jessica Prempeh 1 , Chin Yen Tay 1 , Fanny Peters 1 , David Speers 4 , Anthony D Keil 4 , Peter Richmond 5 , Benjamin Howden 6 , Charlene M Kahler 1 5
  1. Marshall Centre for Infectious Diseases Research and Training, The University of Western Australia, Perth, Western Australia, Australia
  2. Public Health Microbiology, Health Support Queensland Department of Health, Brisbane, Queensland, Australia
  3. Sir Albert Sakzewski Virus Research Centre, Queensland Paediatric Infectious Diseases Laboratory, Brisbane, Queensland, Australia
  4. Department of Microbiology, PathWest Laboratory Medicine WA, Perth, Western Australia, Australia
  5. Telethon Kids Institute, Perth, Western Australia, Australia
  6. Department of Microbiology and Immunlogy, University of Melbourne, Melbourne, Victoria, Australia

Neisseria meningitidis is the causative agent of invasive meningococcal disease which has a mortality rate of 6%. The aim of this study was to analyse differences in the population structure of invasive meningococcal isolates in Western Australia (WA) and Victoria (VIC). Whole-genome sequencing (WGS) has been explored to predict the coverage of the BEXSERO® vaccine by analyzing the sequence variability of the four antigens incorporated in the vaccine: factor H binding protein (fHbp), Neisserial Heparin Binding Antigen (NHBA), Neisseria adhesin A (NadA) and porin A (PorA).

 

The genomic DNA of 409 invasive meningococcal strains isolated in WA (n=278) and VIC (n=131) were sequenced using Illumina paired ends. The SRST2 pipeline was used to determine the allele at each MLST and antigen locus. The combination of the four antigenic variants was used to assign a BEXSERO® antigen sequence type (BAST) to each isolate. The sequence type (ST) and clonal complex (cc) was assigned using the PubMLST database.

 

Twenty and twelve cc were identified in WA and VIC, respectively. The majority of disease in both states was caused by cc41/44 isolates but the predominant ST for this cc was ST-6058 (25%) in VIC and ST-146 (36%) in WA. Of the four antigens, NHBA had the highest associative property with clonal complexes (Cramer’s V coefficient = 0.746). Furthermore, each BAST was restricted to only one clonal complex. Of the 218 BASTs identified, only 17 BASTs were shared by the two regions. The predicted coverage of the BEXSERO® vaccine was 61% (33-78%) for WA and 66% (53-87%) for VIC. The variation in the annual coverage was mainly due to the fHbp antigen. For both regions, a two-year temporal shift was observed in the fHbp variant covered by the vaccine.

 

In conclusion, the predicted coverage of the BEXSERO® vaccine varied over time for Western Australia and Victoria. Also, this study is the first to observe temporal shifts of fHbp variants across transcontinental Australia.