Biochemical and immunological characterization of the extracellular nucleases of group B streptococci.

Open Access
Publisher Website
Google Scholar
Abstract
Nearly all group B streptococcal strains representing the 5 major serotypes produced extracellular nucleases as shown by an agar-well-diffusion technique in DNA-methyl green agar plates. Three different nucleases were isolated and partially purified by DEAE- and CM-cellulose chromatography. They possessed different mobilities on polyacrylamide gel electrophoresis and different MW. These nucleases, designated I, II and III are optimally activated by cations of Ca and Mn and exhibited RNase and DNase activity. Despite differences in their physical and biochemical properties, nucleases II and III appear antigenically similar, but distinct from nuclease I. These group B streptococcal nucleases are immunologically different from nucleases of group A streptococci. Neutralizing activity, probably antibody, to nucleases II and III was found in human sera and was most prevalent in sera of pregnant women colonized with group B streptococci and in their newborn infants.