HIV is the virus that causes AIDS. HIV is classified as a RNA Retrovirus. A retrovirus uses RNA templates to produce DNA. For example, within the core of HIV is a double molecule of ribonucleic acid, RNA. When the virus invades a cell, this genetic material is replicated in the form of DNA. But, in order to do so, HIV must first be able to produce a particular Enzyme that can construct a DNA molecule using an RNA template. This enzyme, Called RNA-directed DNA polymerase, is also referred to as reverse Transcriptase because it reverses the normal cellular process of Transcription. The DNA molecules produced by reverse transcription are then Inserted into the genetic material of the host cell, where they are Co-replicated with the host's chromosomes; they are thereby distributed to All daughter cells during subsequent cell divisions. Then in one or more of these daughter cells, the virus produces RNA copies of its genetic material. These new HIV clones become covered with protein coats and leave the cell to find other host cells where they can repeat the life cycle.
The Body Fights Back As viruses begin to invade the body, a few are consumed by macrophages, which seize their antigens and display them on their own surfaces. Among millions of helper T cells circulating in the bloodstream, a select few are programmed to read that antigen. Binding the macrophage, the T cell becomes activated. Once activated, helper T cells begin to multiply. They then stimulate the multiplication of those few killer T cells and B cells that are sensitive to the invading viruses. As the number of B cells increases, helper T cells signal them to start producing antibodies. Meanwhile, some of the viruses have entered cells of the body - the only place they are able to replicate. Killer T cells will sacrifice these cells by chemically puncturing their membranes, letting the contents spill out, thus disrupting the... [continues]
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