Reverse transcriptase creates double-stranded DNA from an RNA template.
In virus species with reverse transcriptase lacking DNA-dependent DNA polymerase activity, creation of double-stranded DNA can possibly be done by host-encoded DNA polymerase δ, mistaking the viral DNA-RNA for a primer and synthesizing a double-stranded DNA by a similar mechanism as in primer removal, where the newly synthesized DNA displaces the original RNA template.
The process of reverse transcription, also called retrotranscription or retrotras, is extremely error-prone, and it is during this step that mutations may occur. Such mutations may cause drug resistance.