FIG. 1.

(A) Organization of the RV genome. The RV genes (marked by filled boxes) are flanked by noncoding sequences, which contain the terminal promoters for replication and transcription. The 3′-terminal sequence of the positive-sense RNA comprises the AGP, which is inactive in transcription but functional in replication as a strong promoter. The 3′ end of the negative-sense genome RNA comprises the transcriptionally active GP, which is a weak promoter in the replication mode. (B) Organization of the bicistronic model RNA SDI-CL(NP). The reporter genes are separated by the N/P gene border sequence of wt RV, which comprises cis-acting signals for transcription stop/polyadenylation and restart. As in wt RV, the terminal RNA sequences consist of the GP and AGP (positions 1 to 68 and 11763 to 11928 of RV SAD B19). (C) Organization of recombinant ambisense RVs. In SAD Ambi-CAT, the AGP sequence is exchanged for a copy of the GP sequence and the CAT gene sequence is coded on the positive-sense RNA strand in orientation opposite that of the RV genes (15). SAD Ambi lacks the CAT reporter gene.