The Tat protein of equine infectious anemia virus (EIAV) activates cellular gene expression by read-through transcription.

The Tat protein of equine infectious anemia virus, EIAV, was shown to augment viral gene expression, presumably through interaction with the Tat responsive element, TAR. Recently, cell-free polyadenylation assays suggested that perturbation of the EIAV TAR secondary structure diminished polyadenylation efficiency. The present study indicates that the EIAV TAR regulates the efficiency of the 3'-end processing of viral RNA also in transfected cells. Moreover, our data suggest that the provision of the EIAV Tat protein in trans potentiates read-through transcription through the 3' viral long terminal repeat (3' LTR), thus suggesting activation of downstream-located cellular genes.