Research into a Vaccine Against Burkholderia cepacia complex
By Dr Siobhn McClean, Institute of Technology Tallaght, Centre of Microbial Host Interactions
What is Burkholderia cepacia complex? It is a group of very multidrug resistant bacteria found in about 5% of people with CF. It is a problem because once a person with CF is colonised with Cepacia, it is very hard to clear because it is so antibiotic resistant. Dr Siobhn McClean and other researchers in the Institute of Technology Tallaght (ITT) Dublin have been looking at other ways to fight this infection.
One of the areas our group study is how Cepacia attaches to lung cells because attachment of these bacteria to lung cells is critical to the infection process. The idea was that if we knew how the bacteria attached to the lung, it might be possible to stop it attaching and as a result, stop Cepacia causing infections.
We discovered that the Cepacia produces a number of molecules at its surface to help it attach to lung cells. We are now focusing on using these molecules to develop a vaccine to prevent Cepacia infections. The idea of developing a vaccine came from previous work done by others researchers in the 80's on whooping cough. Whooping cough is caused by other bacterium (B. pertussis) that attaches to the cells that line the throat. The vaccine now routinely used in children to prevent whooping cough contains five molecules that Pertussis uses to attach to the throat. By immunising children with these five molecules, called 'antigens', it enables the person to produce protective antibodies so that if they come across these molecules again (usually on the surface of the bacteria the next time), their immune system recognises and attacks these molecules and with them, the bacteria.
Once we found out what these antigens were in Cepacia, we produced them in a purified form and tested them in animal models. We discovered that if animals were vaccinated with these antigens, and were then later infected with Cepacia, the infection could be cleared from their lungs within a few days. Control groups that didn't get the vaccine could not clear the infection and large numbers of Cepacia cells were found in the lungs after the infection. This is very promising as it indicates that the vaccine is having a protective effect.
These are very early stage experiments and it may be two years before trials can be permitted in humans. It is important that the vaccine is safe before testing it in humans. Ultimately, we hope to develop a vaccine that will prevent Cepacia infections in people with CF. We also hope that it can be used therapeutically to help clear existing Cepacia infections.
Centre of Microbial Host Interactions