What type of human cells does the HIV virus target for replication?

The human immunodeficiency virus (HIV) specifically targets immune cells, particularly CD4 T-lymphocytes (also known as helper T cells). These cells are crucial for the functioning of the immune system, as they help coordinate the body's response to infections. When HIV infects these cells, it uses their machinery to replicate itself, leading to a gradual decline in the number of functional immune cells. This depletion of CD4 T cells can weaken the immune system over time, making the individual more susceptible to opportunistic infections and certain cancers, which is a hallmark of acquired immunodeficiency syndrome (AIDS).

In contrast, nerve cells, muscle cells, and red blood cells do not have the receptors or mechanisms that HIV utilizes for entry and replication. For instance, nerve cells are mostly involved in transmitting signals and are not part of the immune response, while muscle cells are involved in movement and do not play a role in immune defense. Red blood cells are responsible for carrying oxygen but do not participate in the immune system's functions in a way that HIV can exploit. Therefore, the targeting of immune cells is what makes HIV unique and explains its devastating impact on the human immune system.