Research group Guy R. Cornelis

Unraveling the sophisticated mechanisms underlying bacterial infectious diseases

Invasive pathogenic bacteria have evolved intriguing means and ways to sabotage our innate immune system. An understanding of their mechanisms can help finding new therapeutic measures to treat infectious diseases.

Plague, the Black Death of the Middle Ages.

The innate immunity is a complex system that constantly clears the human body from invading microorganisms like bacteria. Cells from this system detect bacteria by recognizing specific chemical signatures. They then engulf and destroy bacteria, a phenomenon called phagocytosis. The innate immune system also includes antimicrobial peptides and a specialized degradative enzymatic system called complement. Pathogenic bacteria have evolved many different ways to hide from the innate immunity or to neutralize it.

The injectisome - or how bacteria undermine innate immunity

Many bacteria, including Yersinia pestis, the one that causes the plague or Black Death, have evolved a system to inject effector proteins into the cytosol of animal cells. This process is called type-III secretion (T3S). The effector proteins disarm the cells from the innate immune system by sabotaging their signaling network. The T3S apparatus, called injectisome, is a complex nanosyringe made of more than 25 different proteins. It consists of a basal body and a ca. 60-nm long needle protruding from the surface. Presently, we focus on the atomic structure of the Yersinia injectisome and how it assembles in an ordered way and controls its needle length.

A bacillus that causes fulminant sepsis

Capnocytophaga canimorsus is commonly found in dog's mouths and is responsible for fatal septicemia or meningitis in humans that have been bitten or licked by a dog. These bacteria essentially hide from the human innate immune system and they feed by degrading the animal or human glycoproteins. Our goal is to understand the rare but very severe infections they cause and help with our research developing prevention.