Genetic analysis of regulatory, promoter, and TAR regions of LTR sequences belonging to HIV type 1 Non-B subtypes.

Transcriptional activation of HIV-1 gene expression is controlled by the interaction of sequence-specific transcription factors with the long terminal repeat (LTR). Information about differences between LTR regions in distinct HIV-1 subtypes is scarce. LTR sequences, including regulatory, enhancer, promoter, and TAR regions, were genetically characterized and compared in 59 HIV-1-infected individuals known to be infected with non-B subtypes. Phylogenetic analyses ascribed the LTR regions to the following subtypes: 10A, 2B, 6C, 1D, 2E, 2F, 16G, 3J, 2H, and 2U. Up to 34% of the samples were LTR/PR recombinants. The LTR region revealed a high degree of genetic variability among distinct HIV-1 subtypes and showed several subtype-specific markers, which hypothetically could influence the interactions with cellular transcription factors, leading to different transcriptional levels among distinct HIV-1 clades. To our knowledge, this is the first characterization of LTR sequences belonging to subtypes J and H.