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. Author manuscript; available in PMC: 2019 Oct 1.
Published in final edited form as: J Immunol Methods. 2018 Aug 8;461:37–43. doi: 10.1016/j.jim.2018.08.002

Figure 1. WHO ELISA for measurement of pneumococcal IgG antibodies.

Figure 1.

The figure represents a typical plate well in WHO ELISA. The left side of the figure depicts the initial pre-absorption of sera with cell wall polysaccharide (C-PS) and 22F polysaccharide to neutralize non-protective antibodies (shown in brown).

The right side of the figure illustrates binding of serum pneumococcal IgG antibodies (shown in green) to serotype-specific pneumococcal capsular polysaccharide. Anti-human IgG antibodies (shown in blue) are bound to serum IgG antibodies. Using a chromogenic substrate, optical density is measured, and then converted to antibody concentration.