Enzyme immunoassay reactivities of sera with lysates of an in vitro -grown SS2 strain after each step in sequential adsorption. Optical density values (OD450) were corrected for background and for dilution during adsorption. Swine convalescent sera cocktail sets were sequentially adsorbed with SS2 whole cells, cell lysates, and E. coli whole cells and cell lysates. Following sufficient adsorption with all these antigens, sera were considered to have been completely adsorbed. (A) ELISA plates coated with whole SS2 cells. (B) ELISA plates coated with SS2 cell lysates. The results are expressed as means of absorbance values, and error bars represent the standard errors of the means.