Using fluorescent tags to visualise fungal activity during infection

Using fluorescent tags to visualise fungal activity during infection

Alex Brand

The fungus, Candida albicans, lives as a harmless yeast in the human gut, where its growth is kept in check by the immune system. If immunity becomes suppressed, for example in transplant patients, C. albicans changes shape to produce long filaments called hyphae, which burrow down into internal tissues and cause fatal infections.

To find their way through tissue, hyphae grow and steer by sensing and responding to the conditions around them. It is important for us to understand this sensing and responding process because, if we can find a way to disrupt it, the fungus can no longer invade and is less able to escape from the immune system or treatment with antifungal drugs.

So far we have studied how hyphae grow and respond but the study of how they sense their environment is more challenging. We have developed new proteins that fluoresce inside the fungus when they sense environmental change but they have not been used before in C. albicans.

The aim of this project is to check that the proteins work properly in this fungus before we start using them in experiments involving host tissue. To do this, we will use special microscopy to see which of the proteins starts to fluoresce inside the fungus when we change the conditions on the outside.

This new technology will tell us how the fungus ‘reads’ its environment during three key stages of infection. Firstly, how it decides which way to steer as it penetrates host cell layers, secondly, how it responds to chemical attack by the body’s immune cells and thirdly, how quickly the commonly-used antifungal drugs can reach the fungus once it has invaded.

This information will help to identify points of vulnerability in the fungus that could be exploited in the design of therapeutic treatments.