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HIV infects specifically a certain types of white blood cells crucial to the function of our immune system. You can imagine that once infected, the immune system is gradually impaired, until a point when the immune system is so weak that the infected person cannot defend him/herself against any other opportunistic infections. And it is true that at the moment there is no effective cure for HIV infection. To make matters worse, most infected individuals are unaware of the infection initially and they can easily spread the disease to others by blood/sexual contact.

Therefore, to summarise, HIV is essentially no more dangerous than other infectious agents (Indeed, parasitic and bacterial infections do kill a very large number of people each year worldwide!!). HIV mainly kills by impairing the host's immune system and making them susceptible to other nasty infections e.g. pneumonia.

2007-06-05 09:17:09 · answer #1 · answered by Anonymous · 1 0

The virus attacks white blood cells:

macrophages - engulf and destroy foreign cells, attract other types of white blood cells to the area and trigger inflammation in response to tissue invasion

dendritic cells - alert the immune system that there is an invader

helper T cells - stimulate natural killer cells (which kill tumor cells and cells infected by viruses), launch attacks by other cells of the immune system, bind to another type of cell to trigger repeated rounds of division that produce huge armies of T (& B) cells and are involved in the production of antibodies

This cripples the immune system and leaves it dangerously susceptible to infections and otherwise rare forms of cancer.

There are quite a few types of cells involved in immune response and a lot of them work together to fight off infection by viruses, bacteria, etc...if one step in the process is unavailable, it interferes with the entire systems ability to function correctly.

2007-06-05 09:25:31 · answer #2 · answered by Jess 5 · 1 0

HIV mainly targets CD4 + T cells (helper T cells) but also infects macrophages and dendritic cells. All these cells as described above play different important roles in protecting the body from infection. The reason that HIV infects these cells is because these cells exhibit a couple of receptors that are bound by HIV gp 120 i.e. CD4, CXCR4 and CCR5. See, those who work in HIV research know that if you want to study HIV by using other cells then you have get them to express these receptors or pseudotype the HIV virus.
The body is unable to protect itself once helper T cells, and macrophages are damaged resulting to what is known as secondary immunodeficiency. Immunocompromised patients are prone to opportunistic infections such as TB and other mycobacterial infections, oral thrush, kaposi sarcoma, pneumocystis carinii pneumonia etc. the condition we know as AIDS disease.

2007-06-05 11:48:41 · answer #3 · answered by Anonymous · 0 0

to guard from distant places bodies e.g. bacteria, pathogens, tumours. each and every from time to time it backfires and can attack your individual physique's cells inflicting some situations including Chron's ailment. those are reported as autoimmune ailments

2016-11-05 00:49:35 · answer #4 · answered by ? 4 · 0 0

AIDS targets the "killer T" class of a group of blood cells known as lymphocytes. There are many kinds of lymphocytes in the immune system. One group is known as macrophages. These ameoba like cells engulf foriegn cells and destroy them with powerful enzymes. Body cells are not attacked because the macrophage will only engulf cells with very special markers. The cells which attach these markers are the killer T lymphocytes.

Killer T lymphocytes only mark cells whose surface protiens they are programmed to identify. There are hundreds of different strains of killer T cells, each with a specific target. This is usually either a bacteria or virus whose surface protiens the killer cell is programmed to identify. Killer cells can mark bacteria directly. When viruses multiply inside body cells, some of the foriegn protien emerges on the cell's surface. Cells cluttered with virus protien are then marked by the killer T cell for disposal by a macrophage. If the macrophage can engulf the infected cell before it sheds its virus, the virus is destroyed as well.

Killer cells are unique because the stem cells which produce them mutate when the killer cells are spawned. It is pure chance that a particular killer cell will match a pathogen the body has never encountered, but as time passes, the odds of a successful mutation are increased. When this mutation ocurrs, the killer cell begins to reproduce in responce to the number of pathogens it encounters. Large populations of this one mutation then develop to mark infected cells. Macrophages then move in and destroy the marked cells. If the organism survives the infection, the mutant population decreases, but there will always be a small population of killer cells which specifically target this infection. This is how immunity to viruses is aquired.

Human influenza virus can re-infect its host many times because the virus mutates just a little faster than the killer T cells do. Killer cells appear to show a bit of flexability however, and will often mark infected cells if the differences are small. This keeps the infection in check until a totally effective strain of killer cells manages to evolve through mutation. Deadly strains of influenza develop when the flu undergoes a major mutation. This renders it totally unrecognizable to the immune system and can cause a world wide pandemic. Bird influenza is a potential threat because it is just such a mutation. Fortunately, it hasn't evolved to be able to be spread easily between people. If it does however, the result could kill millions of people.

The AIDS virus has evolved a unique and deadly way of out manuvering the immune system. Instead of trying to hide from killer cells, the virus actually coats itself in protiens which are highly attractive to all strains of killer T cells. The lymphocyte links to the virus, but the virus then invades the cell. The AIDS virus targets the very cells designed to destroy it. Once inside the killer cell, it is immune from attack by macrophages. The AIDS virus then has another clever survival stragety. It can either reproduce like an ordinary virus and eventually kill its host or it can use a special enzyme to transcribe its RNA into DNA and then actually insert its genes into the genes of the killer cell.

This means every time the killer cell divides, it makes another copy of the AIDS virus. If an AIDS victim is then infected with influenza virus, the killer cells divide rapidly to mark the flu infected cells. However, if this strain of killer cell has the AIDS paracite, then AIDS is reproducing as well. Once the population of these infected killer T cells reaches a certain level, it can trigger the AIDS paracite to emerge from its host's DNA and behave like an ordinary virus.

Every killer cell of this infected strain then dies, releasing billions of virus particles. The person then essentially looses their immunity to whatever infectious agent the particular strain of killer T cell was designed to fight. AIDS has yet another stragety to survive. Killer cells themselves can learn to recognize other infected killer cells. AIDS tries to out manuver this by mutating itself. This prevents an infected killer cell from being marked and then destroyed before the virus can multiply and destroy the cell.

Since there are hundreds of strains of killer T cells, a person infected by AIDS does not loose much of their immunity to infection all at once. However, every subsequent infection will release another wave of aids particles and the population of infected killer T cells increases. The number of strains of killer cells then begins to diminish, and this is what causes the massive loss of immunity characteristic of advanced AIDS infections. AIDS does not kill its victim directly but relies on another infectious agent. Because it kills so gradually, it also has a good chance of being passed onto another victim.

FYI: there are a very small group of people whose killer cells are not attracted to the sugary surface protiens of AIDS virus particles and these individuals are highly resistant to AIDS.

2007-06-05 09:43:59 · answer #5 · answered by Roger S 7 · 0 0

T-Cells and white blood cells

2007-06-05 08:49:07 · answer #6 · answered by futurecripthug 2 · 1 0

All of 'em. And the significance of it is this--

Don't have unprotected sex with ANYBODY. In fact, don't have sex with anybody, it's too dangerous! ;-)

2007-06-05 08:48:51 · answer #7 · answered by nora22000 7 · 0 1

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