Characterisation of the South African HIV-1 subtype C complete 5’ LTR, nef and regulatory genes

Abstract

Human immunodeficiency virus type 1 (HIV-1) subtype C has become the major etiological agent in the global and especially African epidemic. To gain better understanding of the genetic diversity and rapid transmission of HIV-1 subtype C, we have characterized the complete 59 long terminal repeat (LTR) region along with the regulatory genes tat and rev as well as the accessory gene nef of 14 South African HIV-1 subtype C isolates. Phylogenetic analysis revealed a subtype C 59 LTR cluster, as well as subclustering of our nef sequences with various subtype C strains separate from the India and China subclusters. At least 3 NF-kB sites were present in the 59 LTR of most isolates and 13 isolates had the subtype C-specific Rev truncation. Some length variation in exon 2 and the absence of a critical cysteine were found in Tat. Residue variation in the myristoylation signal and motifs involved in CD4 and MHC-I down-regulation was recorded in our nef gene sequences.