Fig. 3.

BLV 3′LTR antisense promoter activity and regulatory sequences affecting transcription. a Ideogram showing the three constructs used in luciferase assays, 5′LTR orientation, 3′LTR orientation and 3′LTR orientation with the majority of the U3 deleted (3′∆). Transcription factor binding sites from [24]. b Luciferase levels for the 5′LTR, 3′LTR and 3′∆ constructs. Comparison between the three constructs showed a significant difference among all three (p value <0.0001). c 5′LTR construct alone and co-transfected with a wild type (wt) Tax and transactivation deficient Tax (mut), which carries a E-to-K amino acid change at position 303 [39]. Tax wt caused a significant increase in luciferase levels (p value <0.0001). d Same as c but using the 3′LTR construct. Tax produced a significant (p value <0.001) drop in luciferase levels. e 5′LTR construct, mutation of IRF resulted in a modest but non significant drop in expression. Mutating DAS resulted in a statistically significant (p value <0.01) decrease (in line with previous reports). For 3′LTR, mutation in IRF caused modest, but non significant drop in expression, mutating DAS resulted in a significant drop (p value <0.0001). In the 3′∆ construct, mutating IRF and DAS caused a significant (p value <0.0001) decrease in luciferase levels (Luciferase levels are scaled to the left most construct in b, c and d. In E they were scaled to the appropriate wild type construct. Statistical significance was determined via Tukey’s multiple comparisons test, **p value <0.01; ***p value <0.001; ****p value <0.0001)