How does HIV attack your immune system?

HIV mainly attacks a type of white blood cell known as a CD4+ T cell, also known as a helper T cell, which plays a central role in the body's immune defense against infections. Here's an overview of how HIV attacks the immune system:

1. Infection of CD4+ T Cells:

- HIV enters the body through contact with infected bodily fluids, such as blood, semen, vaginal fluids, or breast milk.

- The virus primarily attacks CD4+ T cells because they have a receptor on their surface called CD4, which HIV uses to attach and enter the cells.

2. Replication of the Virus:

- Once inside a CD4+ T cell, HIV uses the cell's machinery to make copies of itself. Specifically, the virus's genetic material (RNA) is reverse-transcribed into DNA by an enzyme called reverse transcriptase, and the viral DNA then integrates into the host cell's own DNA.

- During the replication process, new copies of HIV are produced and then released from the infected cell into the bloodstream.

3. Spread of Infection:

- The newly produced HIV virions can infect other CD4+ T cells, as well as other types of immune cells like macrophages and dendritic cells.

- Each infected cell can release thousands of new virus particles, leading to a rapid spread of the virus throughout the body.

4. Depletion of CD4+ T Cells:

- As HIV continues to infect and destroy CD4+ T cells, the body's ability to fight off infections weakens. A healthy person typically has a CD4+ T cell count of several hundred to a thousand cells per cubic millimeter of blood. As the HIV infection progresses, the CD4+ T cell count declines.

- When the CD4+ T cell count drops below a certain level (usually less than 200 cells/mm³), the immune system becomes severely compromised, and the person is considered to have AIDS (acquired immunodeficiency syndrome).

In summary, HIV targets and destroys CD4+ T cells, the critical immune cells responsible for coordinating and supporting immune responses against infections. As the number of CD4+ T cells decreases, the body becomes more susceptible to a wide range of opportunistic infections, cancers, and other complications associated with AIDS.