Retrovirus

Retroviruses are more than just pathogens; they are masters of genetic hijacking that have left an indelible mark on the Tree of Life. From the ongoing global challenge of HIV to the ancient "junk DNA" that shapes our biology, retroviruses continue to be a primary focus of medical research and evolutionary study.

: The enzyme reverse transcriptase "back-transcribes" the viral RNA into a double-stranded DNA copy. Retrovirus

: Another enzyme, integrase , carries this viral DNA into the cell's nucleus and "clips" it into the host's own DNA. At this stage, the integrated viral DNA is known as a provirus . Retroviruses are more than just pathogens; they are

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 : Another enzyme, integrase , carries this viral

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 virus attaches to specific receptors on a host cell (like CD4 receptors in the case of HIV) and fuses with the membrane, releasing its RNA and enzymes into the cytoplasm.