Effect of Phenol Extraction of Group A Streptococcus on Titer and Specificity of Fluorescent M-Typing Antisera

Abstract

Vaccines were prepared from three M-serotypes of group A Streptococcus both by conventional heating procedures and by extraction with phenol. The antisera elicited by these vaccines were conjugated with fluorescein and examined by immunofluorescence for titer and specificity. The sera elicited by phenol-extracted cells showed no cross-reactivity in the case of two strains and reduced cross-reactivity with the third. In all cases, phenol-extracted vaccines elicited higher titers than did heat-killed cells. It is suggested that this procedure for vaccine production may facilitate immunofluorescent screening for M-serotypes.