ARCVIR · Archaeal Virology: unravelling the mechanisms of interviral warfare

Archaea are ubiquitous microorganisms that are found in numerous surroundings ranging from extreme environments to the ocean and the human gut and skin. Marine archaea have a huge impact on biogeochemical cycles and the climate, while archaea in the gut influence the human microbiome and health. Archaea can be infected by unusual viruses that are structurally very diverse and have unique infection mechanisms. As viruses are the major predator of archaea, they shape archaeal communities. This project will visualize the mechanisms that viruses use to fight each other to gain access to host cells. This knowledge of viral mechanisms can, for example, be applied to control archaeal populations to increase human gut health or to reduce the production of the harmful greenhouse gas methane by gut archaea of ruminants. Viruses by far outnumber cells and there is an ongoing arms race for survival. Recently, it was observed that in nature half of the microbial cells are infected by viruses at any given time, and this number is even higher for archaea. Thus, viruses often encounter cells that are already infected. Yet, it is unknown what happens in cells when a second virus infects them and how certain viruses are able to inhibit infection by a subsequent virus. With the exception of some well-studied bacteriophages, the molecular mechanisms underlying this process are poorly understood. My project aims to explore the conditions under which exclusion between viruses is induced and which mechanisms underlie this exclusion. I will study this process using viruses from extreme environments (e.g. salt lakes and hot springs) and use novel molecular biology and imaging tools for these models, which allow for the exploration of archaeal viral biology at an unprecedented depth. The outcome will be of lasting impact in the field of microbial virology, and application of this knowledge will enable innovations that stimulate human health, fight global warming and fuel biotechnology.