FIG. 1.

Schematic representations of the RTBV genome and P3 polyprotein. (A) Genome organization. Viral DNA is represented by a thin double line with the sites of the two discontinuities (Δ1 and Δ2) indicated. The thick arrows outside the DNA represent the four viral genes (I, II, III, and IV). The pregenomic RNA is shown as a thin arrow inside the DNA. (B) P3 polyprotein. The locations of the domains corresponding to MP, CP, PR, RT, RH within P3 are shown. Domains with unknown functions are indicated by question marks. Positions of the cleavage sites characterized by Laco et al. (27) and Marmey et al. (30) are indicated by vertical lines and arrows. Other presumed cleavage sites are symbolized by zigzag lines and question marks. Positions of the amino and carboxy termini of CP (p37) and RT (p55 and p62) are indicated. The black circle indicates the position of the zinc finger motif in CP.