Figure 1

The various forms of unintegrated HIV cDNA. Linear cDNA, the product of reverse transcription, is susceptible to a number of fates other than integration into host chromatin as proviral DNA. Autointegration may lead to the formation of truncated or internally rearranged circular forms. Although recombination may yield 1-LTR circles, host factors may also contribute their presence. Host factors, such as those involved in the non-homologous end joining pathway, participate in the formation of 2-LTR circles. Various DNA repair factors and restriction factors may also result in direct degradation of linear cDNA. Collectively, these processes help to explain patterns of unintegrated viral DNA present in infected cells.