This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology (RNA Virus Pa-1,2 & Miscellaneous Viruses), Subject name: Microbiology
An HIV-positive patient asks you if you can tell him the chances of him progressing to symptomatic AIDS. Which one of the following tests would be most useful? 
Select and explain. 
A. CD4 lymphocyte count, B. HIV antibody test, C. HIV PCR, D. Neopterin
C: HIV PCR
Answer: C: HIV PCR 
Explanation: HIV PCR, a nucleic acid amplification test for HIV RNA, has recently been shown to be the most valuable test for: monitoring a patient's progress during triple drug therapy and determining the chances of progression to AIDS. A viral load of 750,000 copies per ml significantly increases the chance of progression to AIDS within 5 years. The other tests listed do not accurately predict progression to AIDS.