Are even better vaccines on the hoRNAzon?

To vaccinate our bodies against lethal diseases, like smallpox, we need to have the pathogen injected into our bodies in order to teach our immune system how to recognise it and fight it. Obviously we cannot use a perfectly healthy microbe for this injection as this would give a result quite opposite to intention. Therefore, many vaccines are made of bacteria or viruses that were killed prior to injection. Killed pathogens can not do any harm to our bodies, but are good enough to teach our immune system what they look like, so that should their healthy counterparts infected us in the future, our white blood cells are fully equipped to fend them off almost immediately. But for some vaccines the immune response isn’t quite as strong as during an actual infection with the living version of the bug.
Leif Sander and colleagues went for a hunt for what it is about living bacteria that makes them more irritating to our immune system. To their (and mine) great surprise the part of bacteria that seems to be doing a big part of the job, was RNA, a kind of molecule present in all living cells. Firstly, they analysed killed bacteria for several kinds of life-building blocks (including DNA and RNA) and found that RNA was the only one that was rapidly destroyed when bacteria were being killed. Their subsequent experiments were quite straightforward – they treated immune cells with either living bacteria, dead bacteria, or dead bacteria mixed with intact bacterial RNA, and measured how aggressively immune cells would react to these treatments. They also used the three mixtures to inject living animals to see how they would response to such vaccinations. In both cases – immune cells cultured in vtiro, and in living animals – the immune response was strong for living bacteria, weaker for dead bacteria, and strong again (or sometimes even stronger) for dead bacteria mixed with bacterial RNA.
Obviously this is the first observation of such kind, but the potential implications of it might be really beneficial. Often vaccines don’t have a 100% success rate, i.e. not all vaccinated people are protected from the actual disease. If in future, we’d be able to develop vaccines which would contain a mix of dead bugs with their intact RNA, we might be able to provide much more successful protection of the population. Watch this field! I certainly will.

1. Detection of prokaryotic mRNA signifies microbial viability and promotes immunity