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
All of the following methods are used for the diagnosis of HIV infection in a 2months old child , except 
Select and explain. 
A. DNA_PCR, B. Viral culture, C. HIV ELISA, D. P24 antigen assay
C: HIV ELISA
Answer: C: HIV ELISA 
Explanation: HIV ELISA is required for detection of antibiodies against the virus, the antibiodies may be present in the infant because of maternal infection also because IgG antibodies can cross the placental barrier .so the presence of Nti HIV antibodies is not reliable for of HIV in 2months old child