Which of the following are primary targets of HIV?

• A. B cells
• B. Helper T cells
• C. Macrophages
• D. Red blood cells

Answer: (B)

HIV mainly targets cells that display the CD4 receptor, using CD4 to gain entry and a co-receptor such as CCR5 or CXCR4 to fuse with the cell. Helper T cells (CD4+ T cells) are the primary targets because they express CD4 and are central to coordinating immune responses; their infection and gradual loss drive the immunodeficiency seen in AIDS. Other cells can be infected (like macrophages) but they are not the main targets, and red blood cells lack the necessary receptors to be infected. B cells are not primarily infected because they don’t rely on the CD4 entry pathway in the same way.