As methods of disease prevention go – vaccination is without comparison. If successful heard immunity can be developed it is a knock-out blow for the pathogen. A biological uppercut from which there is little hope of recovery. It is also a wonderful testament to our medical capabilities that we are able to manipulate our own immune systems – cajoling them to give us protection.
However the battle twixt man and pathogen is never an easy one and the case of meningitis is a perfect example of this. Group B N meningitides – which is responsible for about 50% of cases of meningococcal disease worldwide – has no vaccine. The surface polysaccharides which so often provide rich pickings for vaccine development can’t be targeted as they have antigenic mimicry with polysaccharides in human neuronal tissues.
Continuing the perhaps slightly tired war metaphor – this is the equivalent of mutually assured destruction. If the immune system is primed to attack Group B N meningitides, then it can’t help but to also attack the neuronal system and both pathogen and host will be trapped in a downward spiral of health.
One way around this is to find another group of targets, which in turn has led to exciting developments in reverse vaccinology. Pioneered by Dr Rino Rappuoli this method lays bare the genetic code of pathogenic bacteria allowing potential protein targets to be examined and their antigenicity assessed. But can this really get us to a successful vaccine? Well – laboring the point once again – the history of warfare is littered with code-breakers swinging the balance – and there is no reason to think that our war with meningococcal disease will be any different.
On page 16 we have an in-depth update from the Meningitis Research Foundation as to the difficulties of developing a MenB vaccine and the various approaches that could get around them.