Serum antibodies against vaccine VLPs
IgA
Plant-produced VLPs of GI.4 Chiba 407 (1987) and GII.4 Aomori 2 (2006) (Icon Genetics GmbH) were coated onto separate 96-polystyrene plates (Nunc MaxiSorp) by adding 100 µl per well of a coating solution (GI.4: 4 µg/ml for IgA and 2 µg/ml for total Ig; GII.4: 4 µg/ml for both). After washing, the plates were blocked for 2 h using skim milk, followed by sample incubation for 2 h. After this, plates were incubated for 1 h with horseradish peroxidase-conjugated antibodies against either IgA or total Ig (HRP Goat anti-human IgA, BioLegend; Goat anti-human Ig : HRP, BIO-RAD), followed by 15 min (total Ig) or 30 min (IgA) incubation with the chromogen substrate (3,3′,5,5′-Tetramethylbenzidine, TMB). The coloring reaction was stopped by adding 1N H