Herpesviruses are a third group of common cancer-causing viruses. Two types of herpesviruses have been associated with cancer: the Epstein–Barr virus (EBV) and human herpesvirus 8 (HHV-8). EBV appears to cause all nonkeratinizing nasopharyngeal carcinomas, Epstein–Barr virus-positive diffuse large B-cell lymphomas, not otherwise specified, diffuse large B-cell lymphomas associated with chronic inflammation, Epstein–Barr virus-positive mucocutaneous ulcers,, Lymphomatoid granulomatoses and, in many cases, fibrin-associated diffuse large B-cell lymphoma and intravascular NK/T cell lymphomas. It also appears to cause some cases of lymphoma, including Burkitt's lymphoma (this causal association is especially strong in Africa) and Hodgkin's disease, EBV has been found in a variety of other types of cancer cells, although its role in causing these other cancers is not well established. KSHV/HHV-8 causes all cases of Kaposi's sarcoma, and has been found in some cases of a cancer-related condition called Castleman's disease. Studies involving other kinds of cancer, particularly prostate cancer, have been inconsistent. Both of these herpesviruses are commonly found in cancerous cells of primary effusion lymphoma. Herpesviruses also cause cancer in animals, especially leukemias and lymphomas. Human T cell lymphotropic virus (HTLV-1) was the first human retrovirus discovered by Robert Gallo and colleagues at NIH. The virus causes Adult T-cell leukemia, a disease first described by Takatsuki and colleagues in Japan  and other neurological diseases. Closely related to human T-cell leukemia virus, is another Deltaretrovirus, bovine leukemia virus (BLV), which recently has met the expected criteria to accept a possible infectious agent causation of breast cancer, using sensitive PCR methods to detect BLV, and having samples from women with breast cancer compared to a control sample of women with no history of breast cancer. journal = ref.1: PLoS ONE, doi:10.137/journal.pone.0134304), authors = Buehring GC, Shen HM, Jensen HM, Jin DL, Hudes M, Block G; ref.2: Scientific Reports 9, article number :2949 (2019). authors= Schwingel S, Andreolla AP, Erpen LMS, Frandoloso R, Kreutz LC.