Tat is also a term, found particularly in England, referring to anything which appears shabby, cheap, and tasteless.
Tat is an 86-101 residue trans-acting regulatory protein (9-11 kDa) produced early in HIV-1 infection whose primary role is in regulating productive and processive transcription from the HIV-1 long terminal repeat (LTR).
TAT also stands for Tourist Authority of Thailand, the well respected, government run, tourist authority in Thailand which promotes tourism in that country and aims to protect travellers from being conned my more unscrupulous agents.