What is AIDS ?

HIV is a type of virus called a retrovirus. Like all viruses, it must invade the cells of other organisms to survive and reproduce. HIV multiplies in the human immune system's CD4+ T cells and kills vast numbers of the cells it infects. The result is disease symptoms.

AIDS is caused by infection with a virus called human immunodeficiency virus (HIV). This virus is passed from one person to another through blood-to-blood and sexual contact. In addition, infected pregnant women can pass HIV to their babies during pregnancy or delivery, as well as through breast feeding. People with HIV have what is called HIV infection. Some of these people will develop AIDS as a result of their HIV infection.

How HIV is transmitted

You can become infected with HIV in several ways, including:

Sexual transmission. You may become infected if you have vaginal, anal or oral sex with an infected partner whose blood, semen or vaginal secretions enter your body. You can also become infected from shared sexual devices if they're not washed or covered with a condom. The virus is present in the semen or vaginal secretions of someone who's infected and enters your body through small tears that can develop in the rectum or vagina during sexual activity. If you already have another sexually transmitted disease, you're at much greater risk of contracting HIV. Contrary to what researchers once believed, women who use the spermicide nonoxynol-9 also may be at increased risk. This spermicide irritates the lining of the vagina and may cause tears that allow the virus into the body.

HIV can be transmitted by blood contact. If you receive a blood transfusion from someone with HIV, you will probably get HIV. This is why it is important that people who have HIV do not give blood. You cannot get HIV by giving blood. People who do not have HIV can give blood with no risk of HIV for themselves or for the person who gets the blood. If you are in a profession where you might come into contact with other people's blood, you should be careful to learn and follow the guidelines for dealing with this situation. Your employer should make that information available to you. If this does not happen, I suggest you demand it.

What are the key principles in managing HIV infection?

First of all, there is no evidence that people infected with HIV can be cured by the currently available therapies. In fact, individuals who are treated for up to three years and are repeatedly found to have no virus in their blood experience a prompt rebound increase in the number of viral particles when therapy is discontinued. Consequently, the decision to start therapy must balance the risk of an individual advancing to the stage of symptomatic disease against the risks associated with therapy. The risks of therapy include the short and long-term side effects of the drugs, described in subsequent sections, as well as the possibility that the virus will become resistant to therapy. This resistance then limits the options for future treatment.

Translation

After HIV mRNA is processed in the cell's nucleus, it is transported to the cytoplasm. HIV proteins are critical to this process: for example, a protein encoded by the rev gene allows mRNA encoding HIV structural proteins to be transferred from the nucleus to the cytoplasm. Without the rev protein, structural proteins are not made.

In the cytoplasm, the virus co-opts the cell's protein-making machinery � including structures called ribosomes � to make long chains of viral proteins and enzymes, using HIV mRNA as a template. This process is called translation.