A retrovirus is called "retro" because it utilizes reverse transcriptase to perform a backward (retro) step in the central dogma of molecular biology: converting RNA into DNA.
Traditionally, genetic information flows from DNA to RNA to protein. However, retroviruses circumvent this process by using their RNA genome as a template to create DNA, which is then integrated into the host cell's genome. This "reverse transcription" is the defining characteristic of retroviruses and the reason for the "retro" prefix, indicating a reversal of the usual direction of transcription.
Here's a breakdown:
- Central Dogma: DNA -> RNA -> Protein
- Retrovirus Process: RNA -> DNA (using reverse transcriptase) -> Integration into host DNA
This unusual mechanism was revolutionary when discovered, as it challenged the established understanding of how genetic information is transferred. The term "retro" acknowledges this unconventional and reverse process.
