Retroviruses.
D000163:Acquired Immunodeficiency Syndrome / Q000209:etiology / Q000517:prevention & control; D000818:Animals; D002415:Cats; D002417:Cattle; D002642:Chick Embryo; D006801:Humans; D012190:Retroviridae; D012192:Retroviridae Infections / Q000517:prevention & control / Q000628:therapy / Q000635:transmission