Giant viruses found in Austrian sewage fuel debate over potential fourth domain of life

Tourists visiting the town of Klosterneuburg in eastern Austria often head for the 12th century monastery or the nearby memorial to author Franz Kafka. Virologists and evolutionary biologists, however, may one day pay homage to the town's sewage treatment plant, which has yielded a genome that appears to be from the most cell-like viruses yet. These oddities, challenge the controversial hypothesis that so-called giant viruses are descendants of a vanished group of cellular organisms—a fourth domain of life. Instead, the study argues, these outsized viruses have more pedestrian origins.