HIV Disease and AIDS
Keys to Understanding and Coping
The Attack: How HIV Invades the Immune System
Viruses depend on the cells they infect in order to copy themselves and spread. The AIDS virus, HIV, is no exception. What makes HIV different, however, is its main point of attack.
Unlike other viruses, HIV directly strikes and cripples the immune system -- normally the body's primary defense against infections like HIV.
The invasion: Step by Step...
To reproduce and multiply, HIV first infects a human cell. The CD4 cell is the favorite target.
Once inside the cell, the virus begins to copy itself -- a process known as replication. In effect, HIV turns the cell into a virus-producing factory.
HIV carries with it several substances that allow replication to occur. These are called enzymes and each has a role to play.
Early in the infection, the virus establishes itself in the cell by creating long strips composed of protein and enzymes. To effectively spread the infection, however, these strips must be sliced into smaller elements.
Protease is the enzyme that enables HIV to spread. Think of protease as a sharp chemical blade. Working somewhat like a cutting device on an assembly line, it automatically slices the HIV strips into smaller sections.
The smaller sections or viral particles are assembled in a capsule. The virus is then ready to break away from the CD4 cell and go on to attack other CD4 cells, repeating the above process.
With an increasing number of CD4 cells infected and destroyed, the immune system has fewer quarterbacks to alert and stir the other disease-fighting cells to action -- and the virus expands its attack.
Without treatment, the body will eventually lack sufficient CD4 cells to fight HIV or any other infection.
Questions & Answers
"What is the lymphatic system and...?
The lymphatic system is one of our body's most important defenses against infection. Lymphatic vessels are much like tiny blood vessels and extend throughout the body.
The lymphatic system is vital to health:
- it provides a route for absorption of nutrients;
- it gathers fats, excess fluid, body wastes and other materials, removing them from the cell spaces, and carries them to the blood for eventual elimination.
Lymph nodes are also part of the system. Resembling bunches of lymphatic vessels, they are found in the neck, armpits, around organs and major blood vessels and at other points in the body. Lymph nodes contain large cells that absorb dead tissue and harmful substances.
...what is its link to the spread of HIV?"
The lymph nodes are the HIV recruiting grounds. After the body is infected with HIV, the virus attaches to cells of the lymph nodes.
Meanwhile, CD4 cells are constantly circulating through your blood and lymph systems. As they pass through the lymph nodes, they are infected by the virus lying in wait. CD4 cell counts then decrease as infected cells are destroyed by the virus.
At this stage a person may not show any signs of infection. However, the virus, concentrated in the lymph nodes, continues to multiply and weaken the immune system. Eventually, the virus will destroy the lymph nodes themselves, entering the bloodstream in great numbers.
