CONTRIBUTION OF NF-KAPPA-B AND SP1 BINDING MOTIFS TO THE REPLICATIVE CAPACITY OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 - DISTINCT PATTERNS OF VIRAL GROWTH ARE DETERMINED BY T-CELL TYPES

Starting with a replication-incompetent molecular clone of human immunodeficiency virus type 1, lacking all the NF-kB and Sp1 binding sites present in the native long terminal repeat (LTR), proviruses containing reconstructed LTRs with individual or combinations of NF-kB and Sp1 elements were generated and evaluated for their capacity to produce virus progeny following transfection-cocultivation. Virus stocks obtained from these experiments exhibited a continuum of replicative capacities in different human T-cell types depending on which element(s) was present in the LTR. For example, in experiments involving proviral clones with LTRs containing one or two NF-kappa-B elements (and no Sp1 binding sites), a hierarchy of cellular permissivity to virus replication (peripheral blood lymphocytes = MT4 > H9 > CEM > Jurkat) was observed. Of note was the associated emergence of second-site LTR revertants which involved an alteration of the TATA box. These results suggest that the human immunodeficiency virus type 1 LTR possesses functional redundancy which ensures virus replication in different T-cell types and is capable of changing depending on the particular combination of transcriptional factors present.