In the past, naturally occurring cross subtype neutralizing Abs have already been used as templates for immunogen design but in most of these cases patients were selected using either the classical short PBMC assay (1/2/7 format) or PV assays and our results clearly show that a different group of patients is selected by the extended incubation PBMC assay (24/1/14 format). Testing the patient plasma against primary strains is also more stringent since the molecularly cloned PV seem to be more easily neutralized. Hence, we believe that our selection procedure against the primary ITM panel provided us with patients that had more potent responses.