Virology — MCQs

Question 1441: The virus HIV is produced and propagated in:

• A. Circulating T4 lymphocytes (Correct Answer)
• B. Dendritic cells in the lymph nodes
• C. B-lymphocytes in the lymph nodes
• D. Epithelial cells of the reproductive system

Explanation: ***Circulating T4 lymphocytes*** - HIV primarily targets and replicates within **CD4+ T lymphocytes** (also known as T4 lymphocytes), which are crucial for the immune response. - The virus uses its **gp120 protein** to bind to the **CD4 receptor** and a coreceptor (CCR5 or CXCR4) on these cells, initiating entry and subsequent replication. *Dendritic cells in the lymph nodes* - Dendritic cells can be infected by HIV, but they primarily function as **reservoirs** and vehicles for transporting the virus to lymph nodes, rather than the main site of productive replication. - While they can transfer HIV to CD4+ T cells, the *primary propagation* occurs in the activated T cells themselves. *B-lymphocytes in the lymph nodes* - **B-lymphocytes** lack the primary **CD4 receptor** and co-receptors (CCR5/CXCR4) necessary for efficient HIV entry and replication. - Therefore, B-cells are generally **not productively infected** by HIV and do not serve as a site for significant viral propagation. *Epithelial cells of the reproductive system* - While HIV can be found in bodily fluids of the reproductive system, **epithelial cells** are generally not the target cells for HIV infection and replication. - The virus primarily targets immune cells, particularly **CD4+ T cells and macrophages**, not epithelial cells of mucosal surfaces for propagation.