All of the following methods are used for the diagnosis of HIV infection in a 2 month old child,
Anti-HIV antibody detection by ELISA or any other method is done only after 18 months of birth when all maternal antibodies would have disappeared.
HIV diagnosis <18 months: (i) HIV DNA detection (best), (ii) p-24 antigen, (iii) HIV RNA detection, (iv) virus isolation
DNA-PCR.
Viral culture.
HIV ELISA
p24 antigen assay