Why do we catch colds? How do viruses get into cells? In pursuing this central question, Ari Helenius, Professor of Biochemistry at ETH Zurich since 1997, and his team have pioneered research in this field. For his efforts, Professor Helenius has today been awarded the 'Swiss Nobel Prize' in Bern, Switzerland. "This award is not only for me but for the entire team as well a confirmation of our long years of work, and demonstration of the good working conditions that exist for researchers at ETH Zurich", Professor Helenius said.
Discoverer of Endosomes
Viruses are parasites that need to feed from living cells in order to replicate. The membrane covering each cell creates an effective barrier against infiltration by undesired substances. The supposition to date had been that viruses invade cells through fusion with the plasma membrane, in the same way that two soap bubbles collide with one another, then fuse. Helenius found instead that the vi-ruses are carried by a cellular mechanism to an internal location in the cyto-plasma where the lower pH value promotes penetration into the cytosol and eventually the nucleus. Working from this finding, Helenius discovered the so-called endosome, a structured, intracellular membrane bubble that provides the acidic environment that allows the fusion of virus and cell.
Increased insight into cellular quality control
Virologists are not the only ones to benefit from Helenius's reseach. Cell biolo-gists have also profited. Helenius's work with viruses has led to the identification of underlying mechanisms of cell biology. One of these mechanisms is a quality control system that newly synthesized proteins, such as hormones and en-zymes, have to pass before they are deployed by the cell to perform their func-tion. While studying the synthesis of viral proteins in the infected cell, Helenius and co-workers observed that defective, incorrectly folded viral proteins failed to be transported to the surface of the cell. The quality control system underlying this phenomenon could be shown to also apply to cellular proteins. By subject-ing proteins to a quality check, cells make certain that newly synthesized pro-teins are correctly assembled and folded and do not endanger the functionality of the cell.
By far the greatest importance of Helenius's research with viruses in the area of medicine is how influenza and other viruses infiltrate cells. Proof that there is a system of quality control has additionally led to recognition that defects in the mechanism are the causes of certain illnesses such as particular forms of diabe-tes and cystic fibrosis, an inherited illness that occurs with relative high fre-quency in Europeans. This makes Professor Helenius's work of direct interest in the health field.