FIG. 2.

(A) The clinical isolate preferentially produces SMEZ in vitro. The isolated emm118 strain was grown in vitro, and culture supernatant was used to stimulate human PBL proliferation. Rabbit antisera raised against individual SAgs were used to specifically neutralize SAg activity. Anti-SMEZ antiserum (raised against a 1:1 mixture of recombinant SMEZ-1 and recombinant SMEZ-2) neutralized the majority (92.9%) of the supernatant activity, while antisera against other toxins had no or only minor effects. (B) Patient sera increase in neutralization capacity over time. Patient sera were used to neutralize SAg activity in culture supernatant of the emm118 strain. Significant increase in the neutralizing antibody titer was observed during convalescence. All experiments were carried out in duplicate. The error bars indicate standard deviations.