Human immunodeficiency virus parasitizes which of the following...

Human Immunodeficiency Virus (HIV) specifically targets and parasitizes helper T cells in the human immune system.

Helper T cells are also known as $\text{T}_4$ lymphocytes or CD₄⁺ T cells because they possess CD4 receptors on their surface. The virus uses these receptors to attach to and enter the host cell.

By infecting and subsequently destroying these $\text{T}_4$ lymphocytes, HIV progressively weakens the immune system, which can eventually lead to Acquired Immunodeficiency Syndrome (AIDS).

Answer: $\text{T}_4$ lymphocytes