Identification of lentivirus tat functional domains through generation of equine infectious anemia virus/human immunodeficiency virus type 1 tat gene chimeras.

The structural regions that comprise the functional domains of lentivirus Tat proteins were examined. Chimeric tat genes and chimeric viral promoters were constructed between the distantly related human immunodeficiency virus type 1 (HIV-1) and equine infectious anemia virus (EIAV). These exchange experiments revealed that the EIAV Tat-responsive element recognition domain is formed by two distinct structural regions. Activation domains of both HIV-1 and EIAV Tat contain a conserved core element, but at least HIV-1 Tat requires the presence of additional structural regions. The interchangeable nature of Tat activation domains suggests that these domains act through a common or ubiquitous cellular transcription factor.