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

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:

: Linked to adult T-cell leukemia and certain neurological conditions. HTLV-2 : Associated with milder neurological disorders.