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Most group A streptococcal strains are able to bind immunoglobulin (Ig) in a non-immune manner, and the majority of these strains bind both IgA and IgG. Using molecular cloning and immunochemical techniques, we have purified and characterized the Ig Fc-receptors expressed by four such strains. Two of the strains express a novel type of receptor, designated(More)
Some strains of group B streptococci express a cell surface protein which binds IgA. This report describes some properties of such an IgA receptor and compares it with a previously described IgA receptor from group A streptococci. The group B receptor was released in an almost pure form from bacteria incubated at elevated pH, and could be isolated by(More)
Streptococcus pyogenes, an important human pathogen, expresses several proteins that interact with the immune system of the host. Among the proteins isolated from different bacterial strains are antiphagocytic M proteins, Ig Fc-binding proteins and exotoxins that act as superantigens. Here we report a novel interaction between S. pyogenes and the human(More)
The group B Streptococcus, an important cause of invasive infections in the neonate, is classified into four major serotypes (Ia, Ib, II, and III) based on the structure of the polysaccharide capsule. Since the capsule is a known virulence factor, it has been extensively studied, in particular in type III strains, which cause the majority of invasive(More)
Many Streptococcus pyogenes immunoglobulin-binding proteins have structural similarities to the antiphagocytic M protein, including the well-known C repeats. One of these molecules is the immunoglobulin A-binding protein Arp, which is expressed by a serotype 4 strain for which no antiphagocytic M protein has yet been described. We expressed Arp4 in an S.(More)
Cell surface proteins that bind to the Fc part of immunoglobulin (Ig) A and/or IgG are expressed by many strains of the group A Streptococcus, an important human pathogen. Two extensively characterized proteins in this group of molecules are protein Arp that preferentially binds IgA and protein H that binds IgG. In addition, recent work has shown that many(More)
The M protein family of molecules in the group A streptococcus comprises a number of cell surface proteins that interact with the immune system of the host. One of the proteins in this family is the IgA receptor Arp4, which has C repeats similar to those that characterize the known M proteins. The streptococcal strain expressing Arp4 also expresses a second(More)
Certain strains of group A streptococci are known to bind IgA and/or IgG via a cell surface receptor, which may act as a virulence factor. The distribution of such receptors among routine clinical isolates was studied, using a total of 225 strains and an assay based on the binding of radiolabelled immunoglobulins. Among 194 throat strains isolated during(More)
The 293-amino acid mt A-1 ORF of the A mating-type idiomorph of Neurospora crassa is multifunctional. It confers A mating identity and is responsible for heterokaryon incompatibility. The goal of this study was to dissect the functional regions of mt A-1. New mutants of mt A-1 selected for loss of the incompatibility function were obtained. One new mutant,(More)
Most group A streptococcal strains bind immunoglobulins (Ig) and fibrinogen to their cell walls. It is shown in this paper that the Ig-binding of three different strains was much weaker at 37 degrees C than at room temperature (20 degrees C), whereas the fibrinogen binding was unaffected by temperature. The binding properties and molecular sizes of two(More)