HIV virus life cycle || HIV infection || HIV virus replication

HIV Life Cycle
HIV, the Human Immunodeficiency Virus, replicates through a complex series of steps that exploit the host cell's own machinery. Here's a closer look at the viral ballet from a molecular biology perspective:

1. Binding: This intricate waltz begins with viral envelope glycoproteins, gp120, specifically binding to CD4 receptors and a co-receptor (usually CCR5 or CXCR4) on the surface of a target CD4+ T lymphocyte.

2. Fusion: A conformational change in gp120 triggers fusion with the cell membrane by the transmembrane glycoprotein gp41. This orchestrated move allows the viral capsid containing the viral RNA genome and enzymes to enter the cytoplasm.

3. Reverse Transcription: Inside the cytoplasm, the enzyme reverse transcriptase performs a breathtaking feat – converting the single-stranded viral RNA into double-stranded viral DNA (provirus). This reverse flow of genetic information defies the central dogma of molecular biology.

4. Integration: The newly formed proviral DNA, escorted by the viral integrase enzyme, migrates to the host cell nucleus. There, integrase facilitates the provirus's permanent integration into the host cell's chromosomal DNA, turning the infected cell into a viral factory.

5. Replication: The integrated provirus now dictates the show. Host cell RNA polymerase recognizes the viral promoter, initiating the transcription of viral RNA in various forms – new viral genomic RNA and RNA encoding viral proteins.

6. Assembly: The translated viral proteins, including structural proteins and enzymes like viral protease, gather at the cell membrane. This orchestrated assembly creates new immature virions.

7. Budding: The immature virions hijack the host cell's endoplasmic reticulum and Golgi apparatus, acquiring their viral envelopes studded with gp120 and gp41. Finally, the virions bud out of the cell membrane, ready to infect new targets. The viral protease then matures these budding virions, rendering them infectious.