Papio hamadryas: A species of baboon in the family CERCOPITHECIDAE, which has a well-studied trilevel social structure consisting of troops, bands, and clans.Papio: A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of five named species: PAPIO URSINUS (chacma baboon), PAPIO CYNOCEPHALUS (yellow baboon), PAPIO PAPIO (western baboon), PAPIO ANUBIS (or olive baboon), and PAPIO HAMADRYAS (hamadryas baboon). Members of the Papio genus inhabit open woodland, savannahs, grassland, and rocky hill country. Some authors consider MANDRILLUS a subgenus of Papio.Papio ursinus: A species of baboon in the family CERCOPITHECIDAE found in southern Africa. They are dark colored and have a variable social structure.Theropithecus: A genus of Old World monkeys of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, that inhabits the mountainous regions of Ethiopia. The genus consists of only one species, Theropithecus gelada.Papio anubis: A species of baboon in the family CERCOPITHECIDAE with a somewhat different social structure than PAPIO HAMADRYAS. They inhabit several areas in Africa south of the Sahara.Deltaretrovirus Antibodies: Antibodies reactive with various types of human T-cell leukemia/lymphoma antigens or bovine leukemia virus antigens.Simian T-lymphotropic virus 1: A strain of PRIMATE T-LYMPHOTROPIC VIRUS 2, closely related to the human HTLV-1 virus. The clinical, hematological, and histopathological characteristics of the disease in STLV-infected monkeys are very similar to those of human adult T-cell leukemia. Subgroups include the African green monkey subtype (STLV-I-AGM), for which the nucleotide sequence is 95% homologous with that of HUMAN T-LYMPHOTROPIC VIRUS 1, and the Asian rhesus macaque subtype (STLV-I-MM), for which the nucleotide sequence is 90% homologous with that of HUMAN T-LYMPHOTROPIC VIRUS 1.Papio cynocephalus: A species of baboon in the family CERCOPITHECIDAE found in southern equatorial and east Africa. They are smaller than PAPIO ANUBIS and have a thinner mane.Papio papio: A species of baboon in the family CERCOPITHECIDAE, often used as an animal model for cognitive studies.Deltaretrovirus Infections: Infections caused by the HTLV or BLV deltaretroviruses. They include human T-cell leukemia-lymphoma (LEUKEMIA-LYMPHOMA, T-CELL, ACUTE, HTLV-I-ASSOCIATED).