A 35-year-old man presents to his physician with a 18Kg weight loss over the preceeding 4 months. The man has not been dieting, but has been having abdominal pain, nausea, and diarrhea. He also had a chronic cough. Sputum studies demonstrate Pneumocystis carinii, and esophagogastroduodenoscopy with biopsy demonstrates Candida and Herpes in the esophagus.The pathogen which causes this patient's underlying disease is a member of which of the following groups of viruses?

This man with multiple infections probably has AIDS, in which "wasting" due to infection and weight loss is common. All three of this patient's secondary infections (Pneumocystis pneumonia, Candida esophagitis, and Herpes esophagitis) are considered to be "AIDS-defining illnesses," that indicate that the patient's HIV infection has progressed to the point of producing profound immunosuppression. HIV is a member of the Lentivirus subgroup of retroviruses. This viral family is characterized by prolonged infections, often with a latent period. These viruses are usually inadequately opposed by the host immune response, and often can infect the nervous system. The Retroviridae also include the oncovirus group that includes the human T-cell Leukemia/Lymphotropic virus. The family Retroviridae includes seven subfamilies members, of which two of the families infect humans with pathologic consequences: the delta retroviruses, of which human T cell lymphotropic virus (HTLV) type I is the most impoant in humans; and lentiviruses, of which HIV is the most impoant in humans. Also Know: The Caliciviridae includes the Norwalk virus and the virus that causes Hepatitis E. Coronaviruses cause upper respiratory illnesses. Flaviviruses include the Hepatitis C virus, yellow fever virus, dengue virus, and several encephalitis viruses. Ref: Longo D.L., Fauci A.S. (2012). Chapter 188. The Human Retroviruses. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds),Harrison's Principles of Internal Medicine, 18e.