What system in the body is affected by HIV/AIDS?

HIV/AIDS primarily affects the immune system in the body. Here's a step-by-step explanation:

1. HIV, which stands for Human Immunodeficiency Virus, is a virus that targets the immune system, specifically a type of white blood cell called a CD4 cell (also known as T cells).

2. Once the HIV virus enters the body, it binds to the CD4 cells. The virus then fuses with the cell, releasing its genetic material into it.

3. The virus's genetic material forces the CD4 cell to produce new copies of the HIV virus.

4. These new copies of the virus then leave the CD4 cell, causing it to die. The new copies of the virus go on to infect other CD4 cells and repeat the process.

5. Over time, the number of CD4 cells in the body decreases, weakening the immune system and making it harder for the body to fight off infections and disease.

6. If the number of CD4 cells falls below a certain level, or if certain infections or cancers occur, a person is said to have Acquired Immunodeficiency Syndrome (AIDS), the most advanced stage of HIV infection.

7. Without treatment, the immune system will become severely damaged and life-threatening illnesses such as severe infections or cancers can easily take hold.