FIG 1.

Schematic representation of NF-κB motif diversity in the HIV-1C LTR. The canonical HIV-1B LTR containing two identical NF-κB motifs is presented at the top. Distinct regulatory regions (U3, R, U5, the modulator, the enhancer, and the core promoter) and important transcription factor binding sites are depicted. Not only does the HIV-1C LTR contain more copies of the NF-κB motif (3 or 4 copies), but the additional motifs are also genetically variable (bottom). The three genetically distinct NF-κB motifs present in the C-LTR are denoted H (GGGACTTTCC), C (GGGGCGTTCC [differences are underlined]), and F (GGGACTTTCT). Note that the Sp1III site also contains subtype-specific variations as presented, with B and C representing the respective viral subtypes.