The mechanism by which the integration reaction is completed has not been fully clarified. Unfolding of the integration intermediate resulting from the IN-catalyzed transesterification produces a branched DNA molecule. Denaturation of the host DNA between the points of joining produces DNA gaps at each host-virus DNA junction. How these gaps are repaired is unclear. Well studied host cell gap repair enzymes can carry out this repair step on model virus-host DNA junctions in vitro, providing candidate enzymes. However, efforts to show importance in vivo are complicated by the fact that the functions are either redundant or lethal when mutated.
Because the strand transfer complex formed at the completion of integration is quite stable, there may be a requirement for a disassembly step to remove integrase and potentially other proteins to allow access of the gap repair machinery.
In order to complete the last stages of integration, the viral proteins must be removed, and the gaps at the host virus DNA junctions repaired. The sequence in which the dissembly of PIC occus is not yet understood.