Figure 1.

The different steps of HIV DNA integration into the host genome. (Step 1) 3’ -Processing: The integrase mediates the endonucleolytic cleavage of the two nucleotides GT to expose sticky CA-3’-OH at both 3’-ends of viral cDNA, which forms the pre-integration complex (PIC) with viral and host cofactors. (Step 2) Strand transfer: by transesterification reaction, the hydroxyl groups at the 3’-ends of the processed viral DNA are used to attack opposite strand phosphodiester bonds separated by 5 bases in the 5′ direction, which allows the integration of viral DNA (blue) into the host DNA (red). (Step 3) DNA repair mechanisms allow completion of the process yielding a duplication of host DNA flanking the provirus (light red).