TABLE 1.

Effect on HIV-1 programmed −1 frameshift of a stop codon located immediately 3′ of the slippery sequence

	Frameshift efficiency (%)
HIV constructs	Wild-type (GGG)	UAA	UAG	UGA
pRNAluc2-HIV35	0.8 ± 0.1	0.8 ± 0.1	0.8 ± 0.1	0.8 ± 0.1
pRNAluc2-HIV80	4.8 ± 0.4	5.4 ± 0.6	5.4 ± 0.6	5.2 ± 0.5

Plasmid pRNAluc2-HIV35 contains only the slippery sequence and pRNAluc2-HIV80 contains the slippery sequence plus the complete frameshift stimulatory signal. The wild-type GGG codon that immediately follows the slippery sequence was substituted with a stop codon (UAA, UAG, or UGA). The frameshift efficiencies were calculated from the luciferase activities in the bacterial lysates as described in the text. The values are the means ± standard error of three independent experiments.