Natural immunity against serogroup X Neisseria meningitidis
Dr Gunnstein Norheim, Dr Judith Mueller, Dr Ray Borrow, Prof Andrew Pollard
- Start Date:
19 June 2009
Oxford University, Oxford, UK
Previously an infrequent cause of meningococcal disease, serogroup X N. meningitidis has recently emerged as a cause of increased incidence or large outbreaks of disease, particularly in Niger, Togo and Kenya. There is no vaccine against serogroup X meningococci. It is not known whether the serogroup X polysaccharide is immunogenic in humans and whether antibodies directed against it might be the basis for protective immunity with a vaccine.
The aim of this project is to undertake the first sero-epidemiological study of immunity against serogroup X meningococci in humans. Sera from 200 healthy individuals (100 aged 3-5 years and 100 aged 13 -19 years) from a community affected by serogroup X outbreak in Togo in 2007 will be recruited for blood sampling. They will be compared with sera from 200 healthy individuals with a similar age distribution from Burkina Faso included in a separate study in 2006 and 2008, and further 200 individuals included in the U.K. HPA sero-epidemiology programme. A serum bactericidal activity (SBA) assay tailored to the serogroup X bacterium will be used to analyze all sera.
The relation between resulting SBA titer distribution and regional age-related incidence data on serogroup X meningococcal disease will be explored. The antibody concentrations against serogroup X polysaccharide and outer membrane proteins will also be analyzed, in order to evaluate their relative contribution to the SBA. The serological data provided by this study will inform the role of bactericidal antibodies in population protection against serogroup X disease. Finally, capacity-building activities will be implemented to improve surveillance of meningitis in Togo.