Figure 1

Cartoon representation of SIVtat1ex fitness in vivo. In the absence of CTL against Tat second exon epitopes (Tat 2 ex), SIV encoding two-exon Tat are more fit and replicate to higher levels. The single exon Tat genome is represented by a pink bar with a jagged edge; the two-exon Tat genome is depicted by a green rectangle. Viruses are illustrated as hexagons with inner ovals.