Real world article
(written from a production point of view)
Referenced in the first draft script of the Star Trek: Deep Space Nine seventh season episode "When It Rains...", barion radiation was a type of radiation that was used in the development of the morphogenic virus. Exposure to barion radiation could cause a Changeling's morphogenic enzymes to spike and could also mutate a cell into a virus.
Julian Bashir and Miles O'Brien discovered, during the course of the script, that, at Starfleet Medical, Section 31 had used barion radiation to mutate a cell from Odo into the morphogenic virus that was now infecting him and the rest of the Founders.