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What are the gag, pol, and env genes in a retrovirus genome?

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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.

The genome of a retrovirus typically consists of three primary genes that facilitate the virus's life cycle and structure. These genes are:1

  • gag (group-specific antigen gene): This gene encodes proteins that form the structural components of the virus, specifically the protein shell that houses the viral genome.1
  • pol (polymerase gene): This gene is responsible for encoding three essential enzymes—protease, reverse transcriptase, and integrase—which catalyze the critical steps of retroviral infection, including the conversion of viral RNA into DNA and its subsequent integration into the host cell's genome.1
  • env (envelope gene): This gene encodes the proteins required for the viral lipoprotein envelope, which surrounds the protein shell and assists the virus in recognizing and entering host cells.21