Overview The human immunodeficiency virus (HIV) weakens the body's immune system to the point that it can no longer fight infection. When a person's immune system is impaired, he or she may experience weight loss, persistent low-grade fever, night sweats, and flu-like symptoms. This condition, known as acquired immunodeficiency syndrome (AIDS), can lead to overwhelming infections or cancer. The HIV virus targets certain cells of the immune system and destroys them. It also leads to systemic inflammation, which over time, can damage healthy tissue surrounding infected organs. In addition to destroying CD4+ T cells, which are essential for fighting off viruses, bacteria, and other illnesses, the virus also attacks macrophages, neutrophils, dendritic cells, and even stem cells. As these cells are destroyed, they are replaced at a slow rate, leaving the body more vulnerable to future infections. Infection with the HIV virus can be controlled by a strong immune response. To control HIV infection, your body must be able to recognize the virus itself as well as its components. Your white blood cells, specifically killer T cells, play an important role in controlling HIV by killing virus-infected cells. When a person is born with HIV, their bodies are already producing antibodies against the virus, indicating that their immune systems are functioning normally. It is only when this function is disrupted after birth that diseases such as AIDS can develop.