HIV replication.Illustration of the replication cycle of the human immunodeficiency virus (HIV). The glycoprotein spikes on the viral envelope attach to surface proteins on a T- lymphocyte white blood cell (upper left). The RNA (ribonucleic acid) genome (red) and reverse transcriptase enzyme (spheres) enter the cell. Reverse transcriptase transcribes the single-stranded RNA to double stranded DNA (deoxyribonucleic acid), which can then integrate into the host cell DNA (bottom left). The virus hijacks the cell's nuclear machinery, causing it to produce viral RNA molecules and proteins. The proteins assemble around the RNA forming the viral cores (green triangles), which then bud from the cell, taking part of the membrane as an envelope (lower right).