The human immunodeficiency virus (HIV) attacks the immune system by specifically targeting and infecting CD4+ T cells, which are a type of white blood cell that plays a critical role in coordinating the immune response against infections.
Once inside a CD4+ T cell, HIV uses its own genetic material to replicate and produce more virus particles. The infected cell eventually dies, releasing new virus particles into the bloodstream and further infecting other CD4+ T cells.
Over time, as the number of CD4+ T cells declines, the immune system becomes progressively weaker and less able to fight off infections and other diseases. This leaves the infected person vulnerable to opportunistic infections, which are infections that take advantage of the weakened immune system and can be life-threatening.
In addition to directly targeting CD4+ T cells, HIV can also trigger chronic inflammation and immune activation, which further contributes to the immune system dysfunction seen in HIV/AIDS. This chronic immune activation can also contribute to the development of a number of non-infectious complications, such as cardiovascular disease and cancer.
While antiretroviral therapy (ART) can effectively suppress HIV replication and reduce viral load, it cannot completely cure the infection or restore the immune system to its pre-infection state. Therefore, people living with HIV/AIDS may still be at increased risk for a range of health complications, even when taking ART.