In the early phase of HIV lifecycle, an active virion binds and enters a target cell mainly by specific interactions of the viral envelope proteins with host cell surface receptors. The virion core is uncoated to expose a viral nucleoprotein complex containing RNA and viral proteins. HIV RNA genome is reverse transcribed by the viral Reverse Transcriptase to form a cDNA copy, that gets inserted into host cell DNA. The viral Integrase enzyme is vital to carry out the integration of the viral cDNA into the host genome. The host DNA repair enzymes probably repair the breaks in DNA at the sites of integration.