Figure 3. ELISA method designed to evaluate the relative concentration of specific antibodies (Y) anti-influenza A/H1N1/2009 virus in human serum and plasma.

(A) Adsorption of anti-hystidine antibodies to the assay surface on 96-wells micro-assay plates and blockage of the remaining available surface with a commercial blocking solution. (B) Addition of the recombinant protein HA_50–274-H1N1 (semi-circles). (C) Addition of serum samples potentially containing specific antibodies (Y) against the Influenza A H1N1/2009 virus. The left hand panel illustrates a scenario with a higher concentration of specific influenza antibodies. (D) Addition of a peroxidated anti-IgG human antibody (Y) to specifically bind the retained serum antibodies. (E) The addition of peroxidase substrate (S) enables the enzymatic reaction (S→P) with a proportional development of color.