Medical Research Council
University of Exeter

Our Research


Virulence Mechanisms

Of the millions of fungi that inhabit our planet, just a handful of species can cause diseases in humans. Such species are referred to as pathogenic, or as being virulent.

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A better understanding of how and why the harmful species are virulent will help us to design medicines that prevent disease (such as vaccines), or that detect or cure disease such as diagnostic tools and antifungal drugs.

Virulence mechanisms are strategies used by pathogenic fungi to cause disease in the human host and can be likened to battle tactics.

Virulence mechanisms enable pathogenic fungi to survive within the host, to cause damage to host tissues, to provoke immune responses which themselves escalate tissue damage. Most often, multiple virulence mechanisms are simultaneously deployed, and different mechanisms are activated at different stages of disease.


Image credit

Lucinda Wight


Micrograph of an immune cell, or so-called macrophage, stained in red. It is ingesting an invading fungus Candida albicans (in blue). Green and yellow areas and spots inside the macrophage show where activity and production of compounds to fight the invader are happening.


Image credit

Jude Bains


Micrograph showing cells of the fungus Candida albicans at the different stages of growth and development when transitioning from a yeast form to a filamentous hyphal cell. These are coloured code from white (yeast form, the non-infective) to yellow to green (hyphal form, very infective that causes disease to humans.

Virulence mechanisms enable pathogenic fungi to survive within the host, to cause damage to host tissues, to provoke immune responses which themselves escalate tissue damage. Most often, multiple virulence mechanisms are simultaneously deployed, and different mechanisms are activated at different stages of disease.

To shine a light upon the toolkit of virulence mechanisms used by pathogenic fungi there are a number of approaches we can use to identify them and study their roles during disease. We can study fungal genome sequences to look for differences between pathogenic and harmless fungi.

We can use genetic engineering approaches to ‘confiscate’ individual tools and study the way in which pathogenic behaviour is impacted when the fungus is disarmed.

When we find virulence mechanisms which are essential for the pathogen to infect the host and cause damage we can look for chemicals which disable them. Such chemicals are the starting point for development of new drugs.


Image credit

Tina Bedekovic


Micrograph of the fungus Candida albicans in its filamentous hyphal form taken with a confocal laser microscope. The use of diverse fluorescent dyes allows us to observe individual features inside the fungal cell, such as vacuoles (red) and mitochondria (green). Studying these features allows us to better understand the disease this fungus causes in humans.


Credits

Elaine Bignell (text)
Alexandra Brand (main image)