How does the human immunodeficiency virus (HIV) affect the body?

The human immunodeficiency virus (HIV) specifically targets the immune system, particularly by infecting and destroying CD4 T cells, which are crucial for coordinating the immune response. This weakening of the immune system impairs the body's ability to fight off infections and diseases. As the CD4 cell count decreases, individuals become more susceptible to opportunistic infections that a healthy immune system would typically be able to manage. This process can lead to the progression of HIV to acquired immunodeficiency syndrome (AIDS), where the immune system is severely compromised.

The other options do not accurately reflect the impact of HIV on the body. HIV does not strengthen the immune system, nor is it ineffective regarding immune response. Additionally, while HIV can have systemic effects, its primary impact is not limited to just the respiratory system; it affects the immune system as a whole. Understanding this crucial function of HIV helps in grasping the importance of prevention, treatment, and management strategies for individuals living with the virus.