BBSRC-funded researchers at Cambridge University have shed new light on a common food poisoning bug. Using real-time video microscopy, coupled with mathematical modelling, they have changed our assumptions about Salmonella and how it infects human cells. The research was published in Interface.
Salmonella is an important bacterium to study as it causes a range of diseases in humans and animals. It is capable of growing and reproducing inside macrophages - a type of white blood cell that ingests foreign material - ultimately destroying them. These macrophage cells are key players in the immune response to invaders and so the control of Salmonella within these cells is critical to surviving an infection. However, fundamentally important factors in infection events - such as the rate at which Salmonella infects cells, how frequently this occurs and the probability of infection - had not previously been calculated because it was thought impossible to do so.
Dr Bryant, from the University of Cambridge, said: "Understanding how these bacteria invade, survive, proliferate and kill vital macrophage cells provides a wealth of knowledge to help improve our health. For the first time, we have been able to calculate the rate at which Salmonella can infect macrophages and we have also seen evidence of dual infection and reinfection of a single cell."
Instead of relying on figures from large populations of infected cells, such as changes in total bacterial number over time, finer measurements of the individual steps of infection were considered. The researchers used two independent approaches for their calculations: mathematical modelling of Salmonella infection experiments, and analysis of real-time video microscopy of individual infection events.