The bacterium (germ) Neisseria meningitidis causes meningitis and blood poisoning. N
meningitidis is classified into different serogroups (types), based on its outer
polysaccharide (carbohydrate) capsule. Serogroups A,B,C,W & Y are responsible for the vast
majority of meningococcal disease worldwide.
Older vaccines against types A,C,W & Y contain part of the polysaccharide capsule of the
germ. However, these polysaccharide vaccines do not provide long-term protection against
disease and are less effective in young children, the group most at risk of meningococcal
disease. Newer "conjugate" ACWY vaccines attach a polysaccharide to a protein carrier - these
provoke a good response in young children and can provide long-term protection.
White blood cells called B cells produce antibodies, which are the main components of
protection against meningococcal disease. Although many studies have investigated the immune
response to these vaccines in different age groups by measuring specific antibodies, there is
limited information about the B cells underlying such an immune response. Several different
subsets (populations) of B cells exist in the blood. Previous studies by the investigators
group suggest that different numbers of B cells are produced in response to each vaccine
type. However, little is understood about which subset of B cell is important for antibody
production in response to these polysaccharide or conjugate vaccines.
This study aims to provide detailed information on the immune response to meningococcal
vaccines by investigating the appearance of B cells and their subsets in the blood after
vaccination with the polysaccharide and conjugate vaccines. These observations will help us
understand how polysaccharide and conjugate vaccines stimulate the immune system in different
ways. This knowledge will help in the development of new vaccines that are effective across
all age groups.
The investigators aim to recruit 20 adults aged 30-70 from Oxfordshire. The study will be
funded by the Oxford Vaccine Group.