Editing Reverse transcriptase (section)

===Template switching===

Two [[RNA]] [[genome]]s are packaged into each retrovirus particle, but, after an infection, each virus generates only one [[provirus]].<ref name = Rawson2018>{{cite journal | vauthors = Rawson JM, Nikolaitchik OA, Keele BF, Pathak VK, Hu WS | title = Recombination is required for efficient HIV-1 replication and the maintenance of viral genome integrity | journal = Nucleic Acids Research | volume = 46 | issue = 20 | pages = 10535–10545 | date = November 2018 | pmid = 30307534 | pmc = 6237782 | doi = 10.1093/nar/gky910 }}</ref>  After infection, reverse transcription is accompanied by template switching between the two genome copies (copy choice recombination).<ref name = Rawson2018/>  There are two models that suggest why RNA transcriptase switches templates. The first, the forced copy-choice model, proposes that reverse transcriptase changes the RNA template when it encounters a nick, implying that recombination is obligatory to maintaining virus genome integrity. The second, the dynamic choice model, suggests that reverse transcriptase changes templates when the RNAse function and the polymerase function are not in sync rate-wise, implying that recombination occurs at random and is not in response to genomic damage. A study by Rawson et al. supported both models of recombination.<ref name = Rawson2018 /> From 5 to 14 recombination events per genome occur at each replication cycle.<ref name="pmid26691546">{{cite journal | vauthors = Cromer D, Grimm AJ, Schlub TE, Mak J, Davenport MP | title = Estimating the in-vivo HIV template switching and recombination rate | journal = AIDS | volume = 30 | issue = 2 | pages = 185–92 | date = January 2016 | pmid = 26691546 | doi = 10.1097/QAD.0000000000000936 | s2cid = 20086739 | doi-access = free }}</ref>  Template switching (recombination) appears to be necessary for maintaining genome integrity and as a repair mechanism for salvaging damaged genomes.<ref name="pmid1700865">{{cite journal | vauthors = Hu WS, Temin HM | title = Retroviral recombination and reverse transcription | journal = Science | location = New York, N.Y. | volume = 250 | issue = 4985 | pages = 1227–33 | date = November 1990 | pmid = 1700865 | doi = 10.1126/science.1700865 | bibcode = 1990Sci...250.1227H }}</ref><ref name="Rawson2018" />