This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
Which of the following is not a structural gene of HIV - 
Select and explain. 
A. Gag, B. Polio, C. ENV, D. Tat
D: Tat
Answer: D: Tat 
Explanation: tat is a nonstructural and regulatory gene of HIV REF:ANANTHANARAYANAN TEXT BOOK OF MICROBIOLOGY 9EDITION PGNO.572