THE infamous bacterium Helicobacter pylori, which has been linked
with stomach ulcers, inflammation and even cancer, may soon be flushed out of
its hiding place in the stomach lining by a new vaccine.
Speaking at the conference, Cesare Montecucco of the University of Padua in
Italy described his research into how the bacterium hijacks cells in the stomach
to get food. He told New Scientist that the work has enabled Chiron
Vaccines of Siena to produce the world鈥檚 first vaccine against H.
pylori. Clinical trials of the vaccine are due to begin later this year.
鈥淚t鈥檚 already been fully substantiated in animals,鈥� Montecucco says.
He examined how H. pylori feeds itself once it has arrived in the
stomach and burrowed through the thick layer of mucus lining the gut into the
single layer of cells beneath called the epithelial monolayer. He discovered
that the bacterium injects a toxin called VacA into the doomed cell to which it
has anchored itself. This causes internal structures called late endosomes to
swell up, and spills enzymes called hydrolases out of the infected cell.
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鈥淭hese help to degrade the mucus, so the bacteria can drain substances from
the stomach lumen,鈥� says Montecucco. The VacA toxin also makes the epithelial
cell layer leaky, letting in nutrients from the layer beneath.
VacA may, however, provide a weak point to attack the bacterium. The immune
system can recognise the toxin, which is why it was chosen as one of the targets
in the new vaccine, alongside other proteins from the bacterium.