Obiective: The ability to bind fibrinogen (Fng) is a virulence determinant for a diverse group of bacterial pathogens. Group B streptococcus (GBS) is an important cause of sepsis and invasive infections. The objective of the present work was to obtain novel insights regarding the mechanism of Fng binding by GBS. Methods: We constructed two genomic libraries of GBS using, respectively, the COH-1 and 2603 R/V strains. These libraries were selected using Fng-coated beads as bait. For virulence studies neonatal (24-hour-old) BALB/c mice (Charles River) were inoculated s.c. with a LD90 (60 CFU/pup) of the wild type serotype III GBS strain or with a fbsA defective mutant. Results: After one round of selection of the COH-1 library approximately 10% of the clones strongly reacted against Fng by immunoblot of phage plaques. The percentage of Fng-binding clones rose to 100% after 3 rounds of selection. All reactive clones contained 2-5 repeats of fibrinogen binding protein A (FbsA), a previously described factor shown to mediate adherence and invasion of human epithelial cells. We further show here that FbsA is an important virulence factor, as evidenced by a decreased ability of the fbsA mutant to cause infection. Experiments are underway to characterize the protective activities of FbsA after active immunization with the protein fragments identified by phage display libraries. Moreover we have developed an anti-FbsA neutralizing monoclonal antibody that is being tested for its ability to passively protect neonatal mice from GBS infection. Conclusion:Our data confirm and extend previous studies indicating that FbsA is an important Fng binding factor. Moreover we show that FbsA is an essential virulence factor in vivo.

IDENTIFICATION OF FIBRINOGEN BINDING PROTEIN FRAGMENTS USING GENOMIC PHAGE DISPLAY LIBRARIES OF GROUP B STREPTOCOCCUS / Domina, Maria; Lanza Cariccio, Veronica; Papasergi, Salvatore; Mancuso, Giuseppe; Pietrocola, Giampiero; Rindi, Simonetta; Colombari, Bruna; Teti, Giuseppe; Peppoloni, Samuele; Speziale, Pietro; Felici, Franco; Beninati, Concetta. - (2011), pp. 175-175.

IDENTIFICATION OF FIBRINOGEN BINDING PROTEIN FRAGMENTS USING GENOMIC PHAGE DISPLAY LIBRARIES OF GROUP B STREPTOCOCCUS

PEPPOLONI, Samuele;
2011

Abstract

Obiective: The ability to bind fibrinogen (Fng) is a virulence determinant for a diverse group of bacterial pathogens. Group B streptococcus (GBS) is an important cause of sepsis and invasive infections. The objective of the present work was to obtain novel insights regarding the mechanism of Fng binding by GBS. Methods: We constructed two genomic libraries of GBS using, respectively, the COH-1 and 2603 R/V strains. These libraries were selected using Fng-coated beads as bait. For virulence studies neonatal (24-hour-old) BALB/c mice (Charles River) were inoculated s.c. with a LD90 (60 CFU/pup) of the wild type serotype III GBS strain or with a fbsA defective mutant. Results: After one round of selection of the COH-1 library approximately 10% of the clones strongly reacted against Fng by immunoblot of phage plaques. The percentage of Fng-binding clones rose to 100% after 3 rounds of selection. All reactive clones contained 2-5 repeats of fibrinogen binding protein A (FbsA), a previously described factor shown to mediate adherence and invasion of human epithelial cells. We further show here that FbsA is an important virulence factor, as evidenced by a decreased ability of the fbsA mutant to cause infection. Experiments are underway to characterize the protective activities of FbsA after active immunization with the protein fragments identified by phage display libraries. Moreover we have developed an anti-FbsA neutralizing monoclonal antibody that is being tested for its ability to passively protect neonatal mice from GBS infection. Conclusion:Our data confirm and extend previous studies indicating that FbsA is an important Fng binding factor. Moreover we show that FbsA is an essential virulence factor in vivo.
Palermo
4-8 settembre 2011
Domina, Maria; Lanza Cariccio, Veronica; Papasergi, Salvatore; Mancuso, Giuseppe; Pietrocola, Giampiero; Rindi, Simonetta; Colombari, Bruna; Teti, Giuseppe; Peppoloni, Samuele; Speziale, Pietro; Felici, Franco; Beninati, Concetta
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11380/1062804
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