“…Others have previously demonstrated successful collection and retention of serum antibodies from whole-blood samples spotted on absorbent filter paper. In these studies, serum was evaluated by enzymelinked immunosorbent assay (ELISA) for antibodies to HIV (2,4,23), measles virus (6, 11-13, 24, 29), the malaria parasite, hepatitis C virus (3,5,15), and other pathogens (7,22,28). These studies demonstrated a good correlation between fresh plasma and driedblood samples using standard ELISA techniques, leading to the expectation that antibodies stored in dried-blood spots should be amenable to immunosignaturing.…”