Figure 1.

Overview of the foamy virus (FV) genome organisation. The proviral DNA genome is shown. The gag, pol, and env genes are depicted as boxes. The flanking long terminal repeats (LTRs) comprise the U3, R, and U5 regions, as indicated underneath the 5′ LTR. Transcription starts at the promoter upstream of the R region in the 5′ LTR and at the internal promoter (P and IP, respectively), which are depicted as rectangular arrows. The transactivator protein Tas activates both promoters, as indicated by the arrows. bel2 encodes the Bet protein. The locations of the Cas sequences, PARM, the purine rich elements A–D, as well as the cPPT and 3′ PPT are illustrated. Only the gene products Gag and Pol, which are processed by the viral PR, are shown.