HIV, or human immunodeficiency virus, is the virus responsible for HIV infection. This acronym can refer to either the virus itself or the infection it causes.

AIDS, which stands for acquired immunodeficiency syndrome, represents the most advanced stage of HIV infection. 

HIV specifically targets and destroys CD4 cells (CD4 T lymphocytes), which are crucial for a healthy immune system. The depletion of these cells hampers the body's ability to fend off infections, illnesses, and certain cancers.

Without treatment, HIV can progressively weaken the immune system, leading to a decline in health and potentially advancing to AIDS. This progression increases the risk of contracting other infections, such as hepatitis, tuberculosis, and some sexually transmitted infections.

However, with appropriate treatment, it is possible to prevent HIV from damaging CD4 cells, allowing the immune system to recover and maintain its defense against other infections. 

@Medical Class 901