When HIV enters a cell it carries with it three viral enzymes essential to it's replication.
There are currently three FDA approved Intergrase inhibitors, raltegravir, elvitegravir and dolutegravir. Raltegravir, elvitegravir and dolutegravir are integrase strand transfer inhibitors (InSTIs). InSTIs act by chelating the metallic cationic cofactors, either Mn2+-or Mg2+, on integrase molecule. Without the active metallic cationic cofactors, integrase cannot attach to and bind to the host DNA thereby blocking transfer of the strand of viral DNA into the host DNA.
InSTIs are not approved to be used as a monotherapy. Raltegravir, elvitegravir and dolutegravir are approved to be used as part of combination antiretroviral therapy. There is no human equlvalent of integrase and blocking integrase activity has resulted in few significant side effects.