Figure 2.

Prototype foamy virus (PFV) genome organization with particular reference to the length and structure of the long terminal repeat (LTR) with the canonical U3, R and U5 regions. The retroviral genes (gag, pro-pol, env) are abbreviated as usual. The FV accessory tas and orf-2 reading frames are shown, as well as the spliced reading frame, giving rise to the Bet protein. The start of transcription in the LTR is indicated by an arrow in the enlargement at the bottom. The numbers refer to lengths in kilobase pairs (kbp) or base pairs (bp).