TAT and Kaposi's sarcoma: In particular, mice carrying a transgene containing the BK virus (BKV) early-region and the HIV-1 tat gene, driven by its own promoter (the HIV-1 LTR) (BKV/Tat transgenic mice), develop dermal lesions like the early phases of KS, as well as tumors of different histotype also observed in HIV-positive persons [34,35].