Immunoelectron Microscopic Study of the Location of Group-Specific and Protein Type-Specific Antigens of Group B Streptococci

Wagner, Barbara; Wagner, Manfred; Kubín, V.; M, Rýc

doi:10.1099/00221287-118-1-95

Cited by 20 publications

(15 citation statements)

References 11 publications

(15 reference statements)

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“…Wild-type (WT) and isogenic mutant bacteria were stained with: i) mouse mAb S9 followed by 5 nm gold-labeled IgG; ii) with rabbit pAb anti-PilB followed by 10 nm gold-labeled IgG, and iii) with rabbit pAb anti PilA followed by 20 nm gold-labeled IgG. The mAb S9 decorates the external layer of the capsule [36] and its thickness in strain NEM316 was estimated to be ≈50 nm on ultra-thin sections by transmission electron microscopy (Figure S1). In the absence of the PilB backbone pilin, the PilA adhesin is found at the cell surface without detectable pili (Figure 3A, bottom panel).…”

Section: Resultsmentioning

confidence: 99%

Dual Role for Pilus in Adherence to Epithelial Cells and Biofilm Formation in Streptococcus agalactiae

et al. 2009

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Streptococcus agalactiae is a common human commensal and a major life-threatening pathogen in neonates. Adherence to host epithelial cells is the first critical step of the infectious process. Pili have been observed on the surface of several gram-positive bacteria including S. agalactiae. We previously characterized the pilus-encoding operon gbs1479-1474 in strain NEM316. This pilus is composed of three structural subunit proteins: Gbs1478 (PilA), Gbs1477 (PilB), and Gbs1474 (PilC), and its assembly involves two class C sortases (SrtC3 and SrtC4). PilB, the bona fide pilin, is the major component; PilA, the pilus associated adhesin, and PilC, are both accessory proteins incorporated into the pilus backbone. We first addressed the role of the housekeeping sortase A in pilus biogenesis and showed that it is essential for the covalent anchoring of the pilus fiber to the peptidoglycan. We next aimed at understanding the role of the pilus fiber in bacterial adherence and at resolving the paradox of an adhesive but dispensable pilus. Combining immunoblotting and electron microscopy analyses, we showed that the PilB fiber is essential for efficient PilA display on the surface of the capsulated strain NEM316. We then demonstrated that pilus integrity becomes critical for adherence to respiratory epithelial cells under flow-conditions mimicking an in vivo situation and revealing the limitations of the commonly used static adherence model. Interestingly, PilA exhibits a von Willebrand adhesion domain (VWA) found in many extracellular eucaryotic proteins. We show here that the VWA domain of PilA is essential for its adhesive function, demonstrating for the first time the functionality of a prokaryotic VWA homolog. Furthermore, the auto aggregative phenotype of NEM316 observed in standing liquid culture was strongly reduced in all three individual pilus mutants. S. agalactiae strain NEM316 was able to form biofilm in microtiter plate and, strikingly, the PilA and PilB mutants were strongly impaired in biofilm formation. Surprisingly, the VWA domain involved in adherence to epithelial cells was not required for biofilm formation.

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Section: Resultsmentioning

confidence: 99%

Dual Role for Pilus in Adherence to Epithelial Cells and Biofilm Formation in Streptococcus agalactiae

et al. 2009

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“…Electron microscopy studies exposed the mosaictype appearance of the external bacterial surface (18). Type-specific capsular polysaccharides mask the group B binding sites, rendering the antigen inaccessible for binding unless the polysaccharide is removed or chemically altered (19).…”

Section: The Pathogenmentioning

confidence: 99%

Group B Streptococcus: Prevention of Early-Onset Neonatal Sepsis

Platt

O’Brien²

2003

Obstetrical & Gynecological Survey

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“…All labelling experiments were done using the direct immunoferritin tech- nique. Conjugation of the IgG-fractions of type-and group-specific antisera with ferritin, incubation of walls with the conjugates, and the preparation of the samples for electron microscopy were carried out as previously described (Wagner et a/.. 1980).…”

Section: Bacterial Strains and Growth Conditions The Following Straimentioning

confidence: 99%

“…Using the immunoferritin technique, we have previously shown that the group-specific polysaccharide of group B streptococci (Streptococcus agalactiae) strains 24/60 (type X) and 25/60 (type R) is located on both the outer and inner surfaces of isolated walls whereas the protein antigens R and X are found only on the outer side (Wagner et al, 1980). Recently, Kasper & Baker (1979) used the same technique to demonstrate the type Ia, I1 and I11 polysaccharide antigens of group B streptococci.…”

Section: Introductionmentioning

confidence: 99%

Immunoelectron Microscopic Study of the Location of Group-specific and Type-specific Polysaccharide Antigens on Isolated Walls of Group B Streptococci

Wagner

Kubín

1980

Microbiology

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The ultrastructural locations of the group-specific polysaccharide and the type-specific polysaccharides Ia, Ib, II and III of group B streptococci (Streptococcus agalactiae) were studied on isolated walls by the direct immunoferritin technique. The type polysaccharides were located exclusively on the outer side of the wall on which they formed a distinct capsule. Except for strain 58/59 (type Ia) the thickness of the capsule was characteristic of each strain investigated. In all strains the type-specific ferritin labelling was confined to the outer surface of the capsule. The group-specific polysaccharide could be demonstrated on the inner surface in all strains tested. It could also be demonstrated on the outer surface in strains 59/59 (type Ib) and 8/66 (group B variant) and on most of the walls of strain 58/59 (type Ia). The failure to detect this antigen on the outer side of the walls of strains 60/59 (type II) and 13/63 (type III) and on some walls of strain 58/59 was probably due to the thickness of the type polysaccharide capsule.

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Immunoelectron Microscopic Study of the Location of Group-Specific and Protein Type-Specific Antigens of Group B Streptococci

Cited by 20 publications

References 11 publications

Dual Role for Pilus in Adherence to Epithelial Cells and Biofilm Formation in Streptococcus agalactiae

Dual Role for Pilus in Adherence to Epithelial Cells and Biofilm Formation in Streptococcus agalactiae

Group B Streptococcus: Prevention of Early-Onset Neonatal Sepsis

Immunoelectron Microscopic Study of the Location of Group-specific and Type-specific Polysaccharide Antigens on Isolated Walls of Group B Streptococci

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