Retrovirus -

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

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: Retrovirus

: 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. Scientists estimate that 8% to 9% of the

: 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. The most well-known is , which attacks the