This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
HIV affects CD4 cells by which protein 
Select and explain. 
A. Gp 120, B. GP 41, C. CCR5, D. CXCR4
A: Gp 120
Answer: A: Gp 120 
Explanation: Ref Robbins 8/e p246-247 HIV 1 uses CD 4 to gain entry into T cells and achieve this through it's viral envelope protein known as gp120