Which viral infection is known to affect the immune system?

HIV infection is specifically known for targeting the immune system, particularly the CD4 T lymphocytes, which are crucial for the immune response. The virus progressively depletes these cells, leading to a weakened immune function and making the person more susceptible to opportunistic infections and certain malignancies.

This impact on the immune system is a defining characteristic of HIV, differentiating it from other viral infections. Influenza primarily affects the respiratory system and can lead to systemic symptoms, but it does not have the long-term immunosuppressive effects that HIV does. Hepatitis C mainly affects the liver and can have systemic effects, but it does not specifically undermine the immune system in the way HIV does. Herpes Simplex Virus can cause localized infections and occasional systemic effects but does not systematically compromise the immune system. Thus, the association of HIV with immune system involvement is unique and critical for understanding its pathophysiology and clinical management.