Nine ART naïve HIV-1 subtype C chronically infected pediatric cross-neutralizers (AIIMS_329, AIIMS_330, AIIMS_341, AIIMS_346, AIIMS_355, AIIMS_357, AIIMS_505, AIIMS_509 and AIIMS_510) were recruited for this study from the Pediatric OPD, Department of Pediatrics, AIIMS, New Delhi. 5 ml of blood was drawn by venipuncture under aseptic conditions from all the study subjects. Blood was used for PBMC isolation after separating the plasma by centrifugation at 600 × g. The plasma was heat inactivated at 56°C for 1 h and stored at −80°C for further experiments.