Streptococcus pneumoniae is the most common bacterial cause of pneumonia, meningitis and otitis media in children and adults world-wide. Pneumococcal infections also cause exacerbations of chronic lung disease, particularly COPD and asthma.
The difference between pneumococcal disease and carriage
An important paradox in pneumococcal infection, is that in most people pneumococci are only found harmlessly inhabiting the naso-pharynx. This common harmless state, termed pneumococcal carriage, boosts immunity to pneumococcal disease and is therefore of some benefit to the individual. As pneumococcal carriage is the means by which infection is transmitted, however, it poses a community threat. Recently acquired bacteria can lead to infection. Control of pneumococcal carriage is considered to be the key to controlling disease as it is the means of transmission and the prerequisite of disease.
Why model pneumococcal carriage?
We have established a method of inducing pneumococcal carriage in healthy human volunteers. This model of natural carriage can be used to:
discover how healthy subjects make immune responses to carriage
discover how subjects with risk factors (age, chronic lung disease) make responses to carriage and how this is different from healthy people
test new vaccines for their effect in experimental carriage and
discover how the host alters the biology of the bacteria while it is being carried
The Experimental Human Pneumococcal Carriage (EHPC) consortium
The Experimental Human Pneumococcal Carriage (EHPC) Consortium, funded for 5 years by the Medical Research Council (MRC), will make use of studies in healthy volunteers and patients with increased risk of pneumococcal disease to understand why some people are protected against pneumococcal carriage and others are not. We have developed a method, unique in the world, for inoculating humans safely with live bacteria in order to establish carriage experimentally and have now tested it in over 400 subjects without adverse effects.
Testing new vaccines using EHPC can be done more quickly and at a fraction of the cost of clinical studies (100 subjects rather than many thousands) and so several vaccines can be tested during this Programme, in parallel with the discovery science. This Programme also offers an opportunity for partnership with commercial entities or charities sponsoring particular new vaccines and these funding options will be explored with MRC.
Our Work Packages
The work is organised in 5 Work Packages (WPs):
- WP1 EHPC model further development.
- WP2 host immune responses to carriage.
- WP3 host susceptibility to pneumococcus.
- WP4 vaccine development and the use of experimental carriage as vaccine efficiency end point
- WP5 pneumococcal biology to determine the microbiota effect on EHPC (and vice versa) and the effect of EHPC on the pathogen.
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