HIV, which is also known as the Human Immunodeficiency Virus, attacks and destroys immune cells within the body. As the disease progresses, it leads to Acquired Immunodeficiency Syndrome (AIDS), which is the result of a nearly depleted immune system. Patients with AIDS are very susceptible to infections that can ultimately be fatal.
HIV Life Cycle
There are six main parts to the life cycle of HIV, according to the National Institutes of Health. The first stage involves the virus binding to proteins located on the outside of special immune cells called CD4 positive T cells and entering the cell. In the second step the virus converts its genetic material into DNA, which then allows it to complete the third step, which is the integration of its DNA with that of the T cell. Step four is complete when the host cell has replicated and made proteins out of the virus' DNA. Next the virus will assemble these new proteins to form new copies of the virus, which allows it to complete the final step, escape from the cell.
Initial Infection
When HIV initially infects a person there are some initial symptoms that it can cause, the AIDS organization AVERT explains. These early symptoms are similar to the flu and include a mild fever, a headache, swollen lymph nodes and a sore throat. Avert explains that in only 20 percent of patients are these symptoms severe enough to warrant a trip to the doctor.
Immune System Destruction
After a person has gone through the initial symptoms of an HIV infection, AVERT explains that there is an extended period of time during which the patient shows no symptoms of an HIV infection. During this time the virus is primarily active in the patient's lymph nodes, where it infects and kills immune cells. As a result, while the virus is not causing any symptoms, it is having a deleterious effect on the immune system. This stage of the disease can last for 10 years or more, AVERT explains.
Opportunistic Infections
As the viral infection wears down the immune system, people with an HIV infection become susceptible to infections that normally are unable to affect a person with a healthy immune system. Consequently, these conditions are known as opportunistic infections, the Mayo Clinic explains. Opportunistic infections can cause severe pneumonia and brain infections, as well as chronic diarrhea or unusual spots in the mouth. The appearance of these opportunistic infections is one of the ways in which AIDS is diagnosed.
Other AIDS Symptoms
Some of the symptoms of AIDS are caused by HIV itself. As the virus begins to overrun the body's defenses, it can cause extreme sweating at night as well as a persistent fever that lasts for several weeks. HIV can also cause lymph nodes to be swollen for months at a time, chronic diarrhea and unexplained fatigue.
