Unusual features of integrated cDNAs generated by infection with genome-free retroviruses.

We previously demonstrated that when nonretroviral RNAs are encapsidated in retroviral particles they can be reverse transcribed into cDNAs, which are then integrated into the cellular genome. This transfer of genetic information via retroviral infection has been designated retrofection. Further analyses of three genes transferred in this manner (retrogenes) revealed that each was present in a single copy at a different site in the recipient quail cell genome and included a transcriptional promoter encoded by the encapsidated neo RNA. A unique feature of the retrogenes was a common 16-nucleotide sequence at or near a recombination border, which was not present in either recombination partner. The existence of this sequence suggests a common mechanism of retrogene formation and/or integration mediated by retrofection.