A surface receptor specific for human IgA on group B streptococci possessing the Ibc protein antigen.

Russell-Jones, G.J.; Gotschlich, Emil C.; Blake, M. S.

doi:10.1084/jem.160.5.1467

Cited by 122 publications

(76 citation statements)

References 19 publications

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“…However, many strains of group B Streptococcus also express an IgA-binding protein, designated ␤ or Bac, that is unrelated to M proteins (22,24,64,65). Interestingly, these unrelated streptococcal IgA-binding proteins bind to the same region in IgA-Fc (36), but for unknown reasons ␤ binds poorly to S-IgA, which limits its value as a possible IgA-binding reagent (24).…”

Section: Discussionmentioning

confidence: 99%

Isolation and Detection of Human IgA Using a Streptococcal IgA-Binding Peptide

Sandin

Linse

Areschoug

et al. 2002

The Journal of Immunology

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Bacterial proteins that bind to the Fc part of IgG have found widespread use in immunology. A similar protein suitable for the isolation and detection of human IgA has not been described. Here, we show that a 50-residue synthetic peptide, designated streptococcal IgA-binding peptide (Sap) and derived from a streptococcal M protein, can be used for single-step affinity purification of human IgA. High affinity binding of IgA required the presence in Sap of a C-terminal cysteine residue, not present in the intact M protein. Passage of human serum through a Sap column caused depletion of >99% of the IgA, and elution of the column allowed quantitative recovery of highly purified IgA, for which the proportions of the IgA1 and IgA2 subclasses were the same as in whole serum. Moreover, immobilized Sap could be used for single-step purification of secretory IgA of both subclasses from human saliva, with a recovery of ∼45%. The Sap peptide could also be used to specifically detect IgA bound to Ag. Together, these data indicate that Sap is a versatile Fc-binding reagent that may open new possibilities for the characterization of human IgA.

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Section: Discussionmentioning

confidence: 99%

Isolation and Detection of Human IgA Using a Streptococcal IgA-Binding Peptide

Sandin

Linse

Areschoug

et al. 2002

The Journal of Immunology

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“…The ␤-negative mutant was derived from the ␤-expressing strain A909, a strain of capsular type Ia that expresses both ␤ and the unrelated ␣ protein (10,21,29). The construction of this mutant is described under "Experimental Procedures" and in Fig.…”

Section: Bacteria Expressing ␤ Selectively Bind Fh and Iga In Wholementioning

confidence: 99%

Streptococcal β Protein Has Separate Binding Sites for Human Factor H and IgA-Fc

Areschoug

Stålhammar‐Carlemalm

Karlsson

et al. 2002

Journal of Biological Chemistry

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The group B streptococcus (GBS) is the most important cause of life-threatening bacterial infections in newborn infants. Protective immunity to GBS infection is elicited by several surface proteins, one of which, the ␤ protein, is known to bind human IgA-Fc. Here, we show that the ␤ protein also binds human factor H (FH), a negative regulator of complement activation. Absorption experiments with whole human plasma demonstrated binding of FH to a GBS strain expressing ␤ protein but not to an isogenic ␤-negative mutant. This binding was due to a direct interaction between ␤ and FH, as shown by experiments with purified proteins. Inhibition tests and studies with ␤ fragments demonstrated that FH and IgA-Fc bind to separate and nonoverlapping regions in ␤. Heparin, a known ligand for FH, specifically inhibited the binding between ␤ and FH, suggesting that FH has overlapping binding sites for ␤ and heparin. Bacteria-bound FH retained its complement regulatory activity, implying that ␤-expressing GBS may use bound FH to evade complement attack. The finding that ␤ protein binds FH adds to a growing list of interactions between human pathogens and complement regulatory proteins, supporting the notion that these interactions are of general importance in bacterial pathogenesis.

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“…Surface proteins encoding IgA-binding receptors have been reported in S. pneumoniae, and streptococcal strains of groups A and B, but these proteins specifically bind only H-IgA (Bessen, 1994 ;Cleat & Timmis, 1987 ;Fagan et al, 2001 ;Hammerschmidt et al, 1997 ;Hede! n et al, 1991 ;Johnsson et al, 1994 ;Russell-Jones et al, 1984 ;Serhir et al, 1995 ;Stenberg et al, 1994). Since IgA-binding receptors might play a role in bacterial pathogenesis, we were interested in examining the existence of B-IgAbinding receptors in S. dysgalactiae, an environmental pathogen that can infect and cause subsequent inflammation of the bovine mammary gland.…”

Section: Discussionmentioning

confidence: 99%

“…IgA-binding receptors were also found in Streptococcus agalactiae, including Bac (Hede! n et al, 1991) and β-antigen proteins (Cleat & Timmis, 1987 ;Russell-Jones et al, 1984). Although all of them show specific binding activities to H-IgA, the group A streptococcal receptors bind both serum and secretory IgA (sIgA), whereas the group B streptococcal receptor binds mainly serum IgA .…”

Section: Introductionmentioning

confidence: 99%