Answer: prion

AnswerCrossword Clue
PRIONDovelike petrel
PRIONSouthern seabird
PRIONPetrel bird with saw-toothed bills
PRIONSaw-billed petrel of southern seas
priontiny proteinaceous particle, likened to viruses and viroids, but having no genetic component, thought to be an infectious agent in bovine spongiform encephalopathy, Creutzfeldt-Jakob disease, and similar encephalopathies
priona type of petrel (a small seabird (any marine bird))
prionany of several petrels of the genus Pachyptila, located in the oceans of the Southern Hemisphere and having serrated edges on the bill