Scientists in the UK have identified a switch that enables Salmonella bacteria to sabotage host cells.
Researchers from Imperial College London say that their finding could ultimately lead to drugs that interfere with the switch in order to combat Salmonella and possibly other bacterial infections.
In humans, Salmonella causes diseases ranging from gastroenteritis to typhoid fever. It also causes similar diseases in livestock.
Before the Salmonella cell can replicate inside a much larger human or animal cell and establish an infection, it must first sabotage the cell by injecting it with a cocktail of 'virulence' proteins. These proteins interfere with the cell's defences and help the bacteria to grow.
The new research reveals that a switch needs to be triggered before the bacterial cell can inject its virulence proteins into a host cell.
First, the bacterial cell assembles a needle-like structure on its surface, to deliver the virulence proteins. Then, another set of bacterial proteins pass through the needle and poke a hole in the membrane of the host cell, creating a bridge between the bacterial cell and the host.
During this time, the switch inside the bacterial cell acts like a safety catch, holding the virulence proteins back so they are not delivered prematurely.
Once the hole is created, the bacterial cell recognises the pH of the host cell and this switches off the safety catch. This then allows the virulence proteins to be delivered through the hole into the host cell.
The researchers stress that the research is currently at an early stage but they hope that ultimately, it might be possible to use their findings to design better drugs or vaccines to combat Salmonella-related diseases.
The study has been published today in the journal Science.