: The enzyme reverse transcriptase "back-transcribes" the viral RNA into a double-stranded DNA copy.
: The host cell's machinery mistakenly treats the provirus as one of its own genes, producing viral mRNA and proteins. These components assemble into new, immature viral particles that bud off from the cell. Retrovirus
Because these viruses integrate into the host DNA, they are incredibly difficult to cure. Modern medicine manages these infections with , which targets specific enzymes like reverse transcriptase or protease to stop the virus from replicating. The "Fossil" Record in Our DNA Because these viruses integrate into the host DNA,
Retroviruses are responsible for several significant human diseases. The most well-known is , which attacks the immune system's T-cells and can lead to AIDS . Other notable human retroviruses include: The most well-known is , which attacks the
The hallmark of a retrovirus is its ability to integrate its own genetic material permanently into the host's genome. This process occurs in several distinct stages:
Perhaps most surprisingly, retroviruses have played a massive role in human evolution. When a retrovirus infects a sperm or egg cell, its genetic material can be passed down to future generations. Over millions of years, these "fossil" viruses have accumulated in the human genome and are known as . Scientists estimate that 8% to 9% of the human genome is composed of these ancient viral remnants. While most are now inactive mutations, some have been repurposed by our bodies to help regulate the immune system or even aid in the development of the placenta during pregnancy. Conclusion
: Linked to adult T-cell leukemia and certain neurological conditions. HTLV-2 : Associated with milder neurological disorders.