Final answer:
Protease inhibitors are the class of drugs in HAART regimens that reduce HIV viral load in the blood and boost white blood cell counts by preventing viral replication and maturation.
Step-by-step explanation:
The class of drugs used to treat HIV that reduces the amount of HIV in the blood and increases white blood count is known as protease inhibitors. These are a critical part of highly active antiretroviral therapy (HAART), which aims to decrease the patient's total burden of HIV, maintain function of the immune system, and prevent opportunistic infections. Protease inhibitors work by inhibiting the HIV protease enzyme, preventing the virus from maturing and replicating effectively, thus reducing the viral load to undetectable levels in many patients and leading to an increase in CD4 helper T cell counts.