Final answer:
Retroviral replication occurs within the nucleus of a host cell, where the virus's RNA is reverse transcribed into DNA by the enzyme reverse transcriptase, ultimately leading to the production of new viruses. Retroviruses, like HIV, integrate into the host cell's genome, making them targets for antiviral drugs that inhibit key viral enzymes.
Step-by-step explanation:
Retrovirus replication primarily takes place within the nucleus of the host's cell. These viruses, such as HIV, contain an RNA genome that must undergo reverse transcription into DNA before integrating into the host genome. Retroviruses carry the enzyme reverse transcriptase, which is responsible for this conversion from RNA to DNA. Unlike other RNA viruses that may replicate in the cytoplasm, retroviruses need to transport their reverse transcribed DNA into the nucleus where it integrates into the host cell's DNA and is then used to synthesize new viral components.
The replication process begins when a retrovirus, enveloped with ENV gene-encoded protein, enters a host cell by fusing with the cell membrane. Once in the host cell, the envelope proteins are shed, and the viral RNA is reverse transcribed into complementary DNA (cDNA). This cDNA is converted into double-stranded DNA (dsDNA) and then integrates into the host's genome as a provirus, where it may remain latent for an extended period.
Since retroviruses produce unique enzymes, such as reverse transcriptase, that are not found in uninfected host cells, researchers have been able to develop antiviral drugs that specifically target these viral enzymes. These treatments, including reverse transcriptase inhibitors like AZT, help manage virus levels in infected individuals without negatively affecting the host cell's normal functions.