What is the name of the enzyme that converts RNA to DNA in retroviruses?

The enzyme that converts RNA to DNA in retroviruses is reverse transcriptase.

Reverse transcriptase uses viral RNA as a template to synthesize complementary DNA, a process called reverse transcription. In retroviruses such as HIV, this DNA intermediate is then transported into the host-cell nucleus and inserted into the host genome by another viral enzyme, integrase. The integrated viral DNA is called a provirus.

Retroviral reverse transcriptase performs more than one task. It has RNA-dependent DNA polymerase activity for making DNA from RNA, RNase H activity for degrading the RNA template, and DNA-dependent DNA polymerase activity for completing the second DNA strand. These coordinated activities turn the virus’s RNA genome into double-stranded DNA.

Reverse transcriptase is often confused with RNA polymerase, which makes RNA from a DNA template, and integrase, which inserts viral DNA into the host genome. The enzyme is also medically important: many HIV medicines inhibit either its nucleotide-binding site or another part of its catalytic machinery. Because reverse transcription lacks efficient proofreading, it can introduce mutations that contribute to antiviral drug resistance.