Britannica Sources used in this answer

Why can reverse transcriptase errors cause HIV to mutate rapidly?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Diagram illustrating the process of retrovirus infection and reverse transcription, showing a retrovirus entering a host cell, releasing viral RNA, reverse transcriptase converting RNA to DNA, integration into the host genome, transcription of new viral RNA, assembly of new virions, and budding from the cell. — Reverse transcriptase After a retrovirus infects a cell, an enzyme known as reverse transcriptase converts viral RNA into proviral DNA in the cytoplasm. Proviral DNA then enters the nucleus, where it is incorporated into the host cell's DNA.

Reverse transcriptase is the enzyme responsible for converting the HIV RNA genome into DNA once the virus has entered a host cell.12

The reason this process leads to rapid mutation is that reverse transcriptase lacks the "proofreading" function found in most other DNA-synthesizing enzymes. Because it cannot correct errors during the replication process, many mutations occur as the virus reproduces.2

This high error rate allows HIV to evolve approximately one million times faster than the human genome. These frequent mutations enable the virus to rapidly adapt, helping it escape detection by the immune system and develop resistance to antiretroviral drugs.23