HIV replication. Computer artwork of the replication cycle of the human immunodeficiency virus (HIV), showing virions (green) surrounding a white blood cell (blue). To access the cell, the glycoprotein spikes on the virions attach to surface proteins (purple forks) on the white blood cell. RNA (ribonucleic acid, pink) is then injected into it, along with reverse transcriptase enzymes, to transcribe the RNA into double stranded DNA (deoxyribonucleic acid). This can be seen occurring to the right of the cell nucleus (white). The DNA then integrates into the host cell's chromosomes (blue) and hijacks the cell's nuclear machinery, causing it to produce viral RNA molecules and proteins. These assemble to form the viral cores, which then bud from the cell, taking part of the membrane as an envelope (bottom).