Recombinant Endopeptidases IdeS and IdeZ and Their Potential Application.

Endopeptidases IdeS and IdeZ (streptococcal virulence factors that specifically cleave IgG heavy chains) are of particular interest because of their potential use in biotechnology, medicine, and veterinary. Genes encoding these enzymes were cloned and expressed in Escherichia coli heterologous expression system (ideS was cloned from a Streptococcus pyogenes collection strain; ideZ from Streptococcus zooepidemicus was synthesized). The 6His-tag was introduced into the amino acid sequence of each endopeptidase, and IdeS and IdeZ were purified by metal affinity chromatography to an apparent homogeneity (according to polyacrylamide gel electrophoresis). Purified enzymes were active against human and animal IgGs; their specificity toward human IgGs was confirmed by polyacrylamide gel electrophoresis. Recombinant IdeZ was used for immunological analysis of equine strangles infection (diagnostics and determination of the titer of specific antibodies in blood). Hence, IdeZ can be used in veterinary and sanitary microbiology to diagnose infections caused by Streptococcus equi and S. zooepidemicus in addition to its application in medicine and biotechnology.

Morphology and Ultrastructure of Group A Streptococcus Biofilms.

Light and electron microscopy enables researchers to study the ultrastructure of GAS biofilms formed on abiotic surfaces. Chains of streptococci surrounded by a bluish film are seen under a light microscope after alcian blue staining of preparations grown on coverslips. The extracellular matrix (indicator of biofilm maturity) becomes visible on ultrathin sections in transmission electron microscopy after additional staining with alcian blue; filamentous structures, characteristic of biofilm, are observed in intercellular spaces. The data obtained by scanning electron microscopy also demonstrate the presence of biofilm.