How does HIV replicates in the human body(Download video) HIV belongs to a special class of viruses called retroviruses. An HIV particle is around 100-150 billionths of a metre in diameter. Thats about the same as: • 0.1 microns • 4 millionths of an inch • one twentieth of the length of an E. coli bacterium • one seventieth of the diameter of a human CD4+ white blood cell. Entry to a human cell HIV can only replicate (make new copies of itself) inside human cells. The process typically begins when a virus bumps into a cell that carries on its surface a special protein called CD4. The spikes on the surface of the HIV particle stick to the CD4 and allow them to fuse. The contents of the HIV particle are then released into the cell. Reverse transcription and integration Once inside the cell, the HIV enzyme called reverse transcriptase converts the viral RNA into DNA. Transcription and translation HIV provirus may lie dormant within a cell for a long time. But when the cell becomes activated, it treats HIV genes in much the same way as human genes. First it converts them into messenger RNA (using human enzymes). Then the messenger RNA is transported outside the nucleus, and is used as a blueprint for producing new HIV proteins and enzymes. Assembly, budding and maturation Complete copies of HIV genetic material are contained among the strands of messenger RNA. These gather together with newly made HIV proteins and enzymes to form new viral particles, which are released from the cell, known as budding. The enzyme protease then chops up long strands of protein into smaller pieces, which are used to construct mature viral cores of new HIV particles. The newly matured HIV particles are ready to infect another cell and begin the replication process all over again. In this way the virus quickly spreads through the human body.
Posted on: Wed, 08 Oct 2014 23:02:29 +0000
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