So this method not only allows us to actually determine the presence of the antibody, it also allows us to quantify to determine what the concentration is of that particular antibody in our mixture. So the entire point of this indirect Eliza method is to basically test for that presence of our antibody inside that sample, for example, inside that blood sample. Now, if the individual did not have HIV, they would not have these blue antibodies. And so if these blue antibodies were not present in our mixture, the green antibodies would not have anything to bind to. And so once we wash our well, those green antibodies would be removed. And so once we add the substrate, the substrate would have nothing to actually catalyze that reaction.