Electron microscopy of the replicative events of A25 bacteriophages in group A streptococci

1972 ◽  
Vol 18 (1) ◽  
pp. 93-96 ◽  
Author(s):  
S. E. Read ◽  
R. W. Reed
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Electron Microscope ◽  
Nucleic Acid ◽  
Group A Streptococcus ◽  
Group A Streptococci ◽  
Virulent Phage ◽  
Acid Pool ◽  
Group A ◽  
A Cell

The replicative events of a virulent phage (A25) infection of a group A Streptococcus (T253) were studied using the electron microscope. The first intracellular evidence of phage replication in a cell occurred 30 min after infection with arrest of cell division and increase in the nucleic acid pool. Phage heads were evident in the nucleic acid pool of the cells 45 min after infection. Release of phages occurred by splitting of the cell wall along discrete lines. This appeared to be at sites of active wall synthesis, i.e., near the region of septum formation. Many phage components were released but relatively few complete phages indicating a relatively inefficient replicative system.

scholarly journals STUDIES OF L FORMS AND PROTOPLASTS OF GROUP A STREPTOCOCCI

1963 ◽  
Vol 117 (3) ◽  
pp. 377-399 ◽  
Author(s):  
Earl H. Freimer
Keyword(s):  
Cell Wall ◽  
Membrane Fraction ◽  
Group A Streptococci ◽  
Differential Centrifugation ◽  
Bacterial Membranes ◽  
Group A ◽  
Antigenic Material ◽  
A Cell ◽  
Membrane Antigens ◽  
Gram Positive Cocci

Intact bacterial membranes have been isolated from protoplasts prepared from Group A streptococci by a cell wall-dissolving enzyme. A membrane fraction with identical chemical and serological properties has been obtained by differential centrifugation of mechanically disrupted streptococci. The membrane is chemically distinct from the cell wall and is composed of 72 per cent protein, 26 per cent lipid, and 2 per cent carbohydrate. Capillary precipitin tests and analysis by microdiffusion have demonstrated that the membrane contains antigens distinct from those of the cell wall and from those of the cytoplasm which it envelops. Evidence is presented which demonstrates that this antigenic material is common to the membranes of Group A streptococci, and that it can be distinguished by immunodiffusion from related antigenic substances present in membranes of several other serological groups of hemolytic streptococci. This antigenic material does not cross-react with the membrane antigens of other Gram-positive cocci.

scholarly journals Molecular basis for recognition of the Group A Carbohydrate backbone by the PlyC streptococcal bacteriophage endolysin

2021 ◽  
Author(s):  
Harley King ◽  
Sowmya Ajay Castro ◽  
Amol Arunrao Pohane ◽  
Cynthia M. Scholte ◽  
Vincent A. Fischetti ◽  
...  
Keyword(s):  
Cell Wall ◽  
Active Sites ◽  
Group A Streptococcus ◽  
Attractive Alternative ◽  
Cell Wall Polysaccharides ◽  
Cell Wall Binding ◽  
Progeny Phage ◽  
Group A ◽  
A Cell ◽  
Species Specific

Endolysins are peptidoglycan (PG) hydrolases that function as part of the bacteriophage (phage) lytic system to release progeny phage at the end of a replication cycle. Notably, endolysins alone can produce lysis without phage infection, which offers an attractive alternative to traditional antibiotics. Endolysins from phage that infect Gram-positive bacterial hosts contain at least one enzymatically active domain (EAD) responsible for hydrolysis of PG bonds and a cell wall binding domain (CBD) that binds a cell wall epitope, such as a surface carbohydrate, providing some degree of specificity for the endolysin. Whilst the EADs typically cluster into conserved mechanistic classes with well-defined active sites, relatively little is known about the nature of the CBDs and only a few binding epitopes for CBDs have been elucidated. The major cell wall components of many streptococci are the polysaccharides that contain the polyrhamnose (pRha) backbone modified with species-specific and serotype-specific glycosyl side chains. In this report, using molecular genetics, microscopy, flow cytometry and lytic activity assays, we demonstrate the interaction of PlyCB, the CBD subunit of the streptococcal PlyC endolysin, with the pRha backbone of the cell wall polysaccharides, Group A Carbohydrate (GAC) and serotype c-specific carbohydrate (SCC) expressed by the Group A Streptococcus and Streptococcus mutans, respectively.

scholarly journals Molecular basis for recognition of the Group A Carbohydrate backbone by the PlyC streptococcal bacteriophage endolysin

2021 ◽  
Author(s):  
Harley King ◽  
Sowmya Ajay Castro ◽  
Juan Bueren-Calabuig ◽  
Amol Arunrao Pohane ◽  
Cynthia M Scholte ◽  
...  
Keyword(s):  
Cell Wall ◽  
Active Sites ◽  
Group A Streptococcus ◽  
Binding Pocket ◽  
Attractive Alternative ◽  
Side Chains ◽  
Cell Wall Polysaccharides ◽  
Progeny Phage ◽  
Group A ◽  
A Cell

Endolysins are peptidoglycan (PG) hydrolases that function as part of the bacteriophage (phage) lytic system to release progeny phage at the end of a replication cycle. Notably, endolysins alone can produce lysis without phage infection, which offers an attractive alternative to traditional antibiotics. Endolysins from phage that infect Gram-positive bacterial hosts contain at least one enzymatically active domain (EAD) responsible for hydrolysis of PG bonds and a cell wall binding domain (CBD) that binds a cell wall epitope, such as a surface carbohydrate, providing some degree of specificity for the endolysin. Whilst the EADs typically cluster into conserved mechanistic classes with well-defined active sites, relatively little is known about the nature of the CBDs and only a few binding epitopes for CBDs have been elucidated. The major cell wall components of many streptococci are the polysaccharides that contain the polyrhamnose (pRha) backbone modified with species-specific and serotype-specific glycosyl side chains. In this report, using molecular genetics, microscopy, flow cytometry and lytic activity assays, we demonstrate the interaction of PlyCB, the CBD subunit of the streptococcal PlyC endolysin, with the pRha backbone of the cell wall polysaccharides, Group A Carbohydrate (GAC) and serotype c-specific carbohydrate (SCC) expressed by the Group A Streptococcus and Streptococcus mutans, respectively. Molecular dynamics simulations reveal a previously unidentified binding pocket that is regulated by a gatekeeper residue and uncover that a previously reported inactive PlyC mutant is locked into a 'closed' conformation. Docking studies with the short GAC backbone oligosaccharides expose potential protein-carbohydrate interactions and are consistent with PlyCB binding to the unmodified pRha or pRha decorated with the GAC side chains.

scholarly journals VARIATION IN THE GROUP-SPECIFIC CARBOHYDRATE OF GROUP A STREPTOCOCCI

1955 ◽  
Vol 102 (1) ◽  
pp. 11-28 ◽  
Author(s):  
Maclyn McCarty ◽  
Rebecca C. Lancefield
Keyword(s):  
Cell Wall ◽  
Chemical Structure ◽  
Group A Streptococci ◽  
Qualitative And Quantitative ◽  
Apparent Loss ◽  
Group A ◽  
A Cell ◽  
Serological Specificity

The phenomenon of apparent loss of group-specific carbohydrate in the course of mouse passage of group A streptococci has been subjected to further study, and several additional variants showing this property have been described. The loss of group reactivity is shown to be due to an alteration in the chemical structure and serological specificity of the cell wall carbohydrate. This alteration appears to be essentially the same in each of the variants available for study. The carbohydrate of the variant strains (V) contains the same two monosaccharide components as the group A carbohydrate (A), but they are present in different proportions. Precipitating sera reactive with V carbohydrate have been prepared, and the A and V carbohydrates have been compared by qualitative and quantitative precipitin analysis. A second type of variation has been encountered during mouse passage. This variation is characterized by the occurrence of a cell wall carbohydrate (I) intermediate in chemical and serological properties between the A and V carbohydrates. The I carbohydrate reacts with both A and V antisera and does not appear to be a simple mixture of A and V carbohydrate. Similarly, antisera against the intermediate strain contain antibodies reactive with both A and V carbohydrates, and evidence is presented indicating that in part this represents antibody with double specificity.

scholarly journals THE LYSIS OF GROUP A HEMOLYTIC STREPTOCOCCI BY EXTRACELLULAR ENZYMES OF STREPTOMYCES ALBUS

1952 ◽  
Vol 96 (6) ◽  
pp. 569-580 ◽  
Author(s):  
Maclyn McCarty
Keyword(s):  
Cell Wall ◽  
Extracellular Enzymes ◽  
Group A Streptococci ◽  
Carbohydrate Component ◽  
Streptococcal Cell Wall ◽  
Intact Cells ◽  
Enzymatic Lysis ◽  
Streptomyces Albus ◽  
Group A ◽  
Isolated Cell

Cell wall preparations of uniform chemical constitution have been obtained from several strains of group A streptococci. The isolated cell walls are dissolved by the same fractions of the Streptomyces albus enzymes that are effective in the lysis of intact cells, and it is likely that enzymatic lysis of group A streptococci is effected by an attack on the cell wall. The streptococcal cell wall, as prepared in this study, consists of approximately two-thirds carbohydrate and one-third protein. Small amounts of other components may be present. The carbohydrate component, which is composed primarily of N-acetyl-glucosamine and rhamnose, is the group-specific C carbohydrate. The evidence indicates that one of the streptomyces enzymes is directed toward the carbohydrate component of the cell wall.

scholarly journals Value of rapid test for identification of beta hemolytic Streptococcus antigens in children with Streptococcal pharyngitis

2004 ◽  
Vol 132 (suppl. 1) ◽  
pp. 39-41 ◽  
Author(s):  
Branimir Nestorovic ◽  
Suzana Laban-Nestorovic ◽  
Veselinka Paripovic ◽  
Katarina Milosevic
Keyword(s):  
Group A Streptococcus ◽  
Rapid Test ◽  
Streptococcal Pharyngitis ◽  
Early Spring ◽  
Group A Streptococci ◽  
Upper Respiratory Tract ◽  
Isolation And Identification ◽  
Cervical Lymph Nodes ◽  
Group A ◽  
Tract Infections

Beta-hemolytic group A streptococcus (Streptococcus pyogenes) is the most common bacterial agent associated with the upper respiratory tract infections in humans. The most frequently group A streptococcus-associated disease is pharyngitis. Males and females are equally affected by group A streptococcus. There is seasonal increase in the prevalence of group A streptococcus-associated pharyngitis. Streptococcal pharyngitis is most prevalent in winter and early spring with higher incidence of disease observed in crowded population such as school children. Early diagnosis and treatment of group A streptococcal pharyngitis has been shown to reduce the severity of symptoms and further complications such as rheumatic fever and glomerulonephritis. The conventional methods used for identification of group A streptococci depend on isolation and identification of the organism on blood agar plates. These methods usually require 18-24 hours of incubation at 37?C. Such delay in identifying the group A streptococcus has often made physicians to administer therapy without first disclosing the etiological agent. Development of immunologic tests, capable of detecting the group A streptococcal antigen directly from the throat swabs, produced rapid test results employed for better treatment of patients. STREP A test is a rapid immunochromatographic test for the detection of group A streptococci from throat swabs or culture. The accuracy of the test does not depend on the organism viability. Instead, group A strep antigen is extracted directly from the swab and identified using antibodies specific for the group A carbohydrates. We compared rapid test with conventional throat swab in 40 children, who met Centor criteria for streptococcal pharyngitis (absence of cough, high fever, purulent pharyngitis, enlarged and painful cervical lymph nodes). Overall congruence of rapid test and culture was 94%. Test is easy to perform and it is recommended as the first diagnostic test for management of children with streptococcal pharyngitis. In children with negative test, but with characteristics highly suggestive of streptococcal infection, throat culture should be performed.

scholarly journals Electron Microscopy of Group A Streptococci After Phagocytosis by Human Monocytes

1971 ◽  
Vol 4 (6) ◽  
pp. 772-779 ◽  
Author(s):  
Alan D. Glick ◽  
Richard A. Getnick ◽  
Roger M. Cole
Keyword(s):  
Electron Microscopy ◽  
Group A Streptococci ◽  
Human Monocytes ◽  
Group A

scholarly journals Doubly Branched Hexasaccharide Epitope on the Cell Wall Polysaccharide of Group A Streptococci Recognized by Human and Rabbit Antisera

2005 ◽  
Vol 73 (10) ◽  
pp. 6383-6389 ◽  
Author(s):  
Francis Michon ◽  
Samuel L. Moore ◽  
John Kim ◽  
Milan S. Blake ◽  
France-Isabelle Auzanneau ◽  
...  
Keyword(s):  
Cell Wall ◽  
Rabbit Antiserum ◽  
Cell Wall Polysaccharide ◽  
Group A Streptococci ◽  
Group B Streptococci ◽  
Group A ◽  
Streptococcal Polysaccharide ◽  
Synthetic Oligosaccharides ◽  
Group B ◽  
Dominant Epitope

ABSTRACT A number of epitope specificities associated with the cell wall polysaccharide antigen of group A streptococci were identified in a polyclonal rabbit antiserum induced in rabbits by whole group A streptococci and in polyclonal convalescent human antisera from children that had recovered from streptococcal A infections. The identification was achieved by using a series of synthetic oligosaccharides, glycoconjugates, and bacterial polysaccharide inhibitors to inhibit the binding of the group A helical polysaccharide to the polyclonal antisera. The exclusively dominant epitope expressed in the convalescent human antisera was the doubly branched extended helical hexasaccharide with the structure α-l-Rhap(1→2)[β-d-GlcpNAc(1→3)]α-l-Rhap(1→3)α-l-Rhap(1→2)[β-d-GlcpNAc(1→3)]α-l-Rhap. The hexasaccharide epitope also bound with the highest immunoreactivity to the rabbit antiserum. In contrast, the human antisera did not show significant binding to the singly branched pentasaccharide with the structure α-l-Rhap(1→2)α-l-Rhap(1→3)α-l-Rhap(1→2)[β-d-GlcpNAc(1→3)]α-l-Rhap or the branched trisaccharide α-l-Rhap(1→2)[β-d-GlcpNAc(1→3)]α-l-Rhap, although both these haptens bound significantly to the same rabbit antiserum, albeit with less immunoreactivity than the hexasaccharide. Inhibition studies using streptococcal group A and B rabbit antisera and the inhibitors indicated above also suggested that the group A carbohydrate, unlike the group B streptococcal polysaccharide, does not contain the disaccharide α-l-Rhap(1→2)α-l-Rhap motif at its nonreducing chain terminus, stressing the importance of mapping the determinant specificities of these two important streptococcal subcapsular group polysaccharides to fully understand the serological relationships between group A and group B streptococci.

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