An almost inexhaustible variety of influenza viruses circulates in waterfowl (ducks, geese), where they mainly grow in the intestines and are excreted in the feces. Occasionally – frequently via a detour through poultry or pigs – they infect people and set off the often fatal avian flu. The human influenza virus, which occurs every winter, multiplies in the lungs and is generally transmitted by breathing in air that is contaminated with the virus (droplet infection). Human and avian viruses are exposed to different environmental conditions, i.e., water or air, at different temperatures, while being passed between individuals.
In order to be transferable between people, an avian virus has to adapt itself to a different form of transmission. "We assume that this adaptation requires changes in the viral lipid envelope, in addition to a new form of receptor recognition," said PD Dr. Michael Veit from the Institute of Virology at Freie Universität.
To be fully transmissible, the viral envelope must meet different requirements: the membrane must be liquid at the body temperature of its host (42°C in birds and 33°C in the human respiratory tract), so that the virus can penetrate into the cells. The envelope needs to solidify quickly when leaving the body in order to protect the virus from damage. The state of the membrane (solid or liquid) depends on the ambient temperature, but the lipid composition determines the temperature at which the state change occurs, as with butter and margarine, which become liquid and spreadable at different temperatures due to the content of different fats.
PD Dr. Michael Veit explains, "Using biophysical approaches we will compare the complex lipid composition of the human influenza virus with the avian influenza virus and investigate the mechanical properties of the viral envelope under changing environmental conditions." In addition, the researchers will investigate which viral proteins select lipids for incorporation into the viral membrane and how the specific lipid interactions affect the morphology and growth of the virus.
The three-year project is entitled "Molecular Patterns of Influenza Virus Envelope Adaptation to Interspecies Transmission." Besides PD Dr. Michael Veit from Freie Universität Berlin, the principal investigators are Prof. Dr. Lukas Tamm from the University of Virginia Medical School, Prof. Dr. Markus Wenk from the National University of Singapore, and Prof. Dr. Kay Grünewald from the University of Oxford.
PD Dr. Michael Veit was born in 1960. He majored in biology at Justus Liebig Universität Gießen and earned his doctorate in 1990 from Phillips Universität Marburg. With the exception of a two-year research period in the laboratory of the Nobel laureate James E. Rothman in New York, he has worked as a researcher at Freie Universität Berlin's Department of Veterinary Medicine since 1991, where he completed the habilitation process in 2001 in virology and biochemistry. Veit's main area of research is the cell biology of influenza as well as arteriviruses, in particular, economically important pathogens that occur worldwide in swine herds.