Final answer:
Essential cis-acting elements of HIV-1 based lentiviral vectors include the Gag gene for virus-like particle formation, RT gene for reverse transcription, Prt gene for protease, and Int gene for integrase, which are crucial for viral replication and integration into the host genome.
Step-by-step explanation:
The essential cis-acting elements of HIV-1 based lentiviral vectors include the following:
- Gag gene: Encodes group-specific antigen, a protein that forms a virus-like particle that will contain reverse-transcribed transposon DNA.
- RT gene: Encodes the reverse transcriptase that will make reverse-transcribed copies of retrotransposon transcript RNAs.
- Prt gene: Encodes a protease that will break down the virus-like particle as the retrotransposon enters the nucleus.
- Int gene: Encodes integrase required for integration of the retrotransposon into a genomic DNA insertion site.
These elements are critical for the replication and integration of the viral vector's genetic material into the host genome. Compared to retrotransposons, HIV and other retroviruses use an ENV-encoded protein envelope surrounding the retroviral DNA to facilitate infection, and upon attachment to a host cell, viral RNA is reverse transcribed. The integrase enzyme then assists in integrating the viral DNA into the host genome.