The retroviral life cycle.

Binding of the virus to the cell is mediated by specific interactions with the viral envelope and cellular receptors. The diploid RNA genome is released into the cytoplasm, where a double-stranded complementary DNA is formed through the action of viral reverse transcriptase. A circular double-stranded DNA intermediate is incorporated as part of the preintegration complex, which gains access to the nuclear contents either during mitosis or by direct nuclear transmigration in the case of lentiviruses. The proviral genome is subsequently integrated into the chromosomal DNA, a reaction mediated by the viral integrase protein. After integration, the provirus is stably passed to daughter cells following cell division.