Binding of collagen to Staphylococcus aureus Cowan 1

Collagen Binding Proteins of Gram-Positive Pathogens

Collagens are the primary structural components of mammalian extracellular matrices. In addition, collagens regulate tissue development, regeneration and host defense through interaction with specific cellular receptors. Their unique triple helix structure, which requires a glycine residue every third amino acid, is the defining structural feature of collagens. There are 28 genetically distinct collagens in humans. In addition, several other unrelated human proteins contain a collagen domain. Gram-positive bacteria of the genera Staphylococcus, Streptococcus, Enterococcus, and Bacillus express cell surface proteins that bind to collagen. These proteins of Gram-positive pathogens are modular proteins that can be classified into different structural families. This review will focus on the different structural families of collagen binding proteins of Gram-positive pathogen. We will describe how these proteins interact with the triple helix in collagens and other host proteins containing a collagenous domain and discuss how these interactions can contribute to the pathogenic processes.

In vitro characterization of representative clinical South African Staphylococcus aureus isolates from various clonal lineages

Data concerning the virulence and pathogenesis of South African strains of Staphylococcus aureus are limited. We investigated host–pathogen interactions of randomly selected clinical S. aureus isolates representing various clones. We characterized the ability of isolates to adhere to fibronectin, fibrinogen, collagens IV and VI, to invade host cells and to induce cell death in vitro. We analysed the possible association of these results with characteristics such as methicillin resistance, Panton–Valentine leucocidin (PVL) positivity and clonality. The S. aureus isolates displayed diversity in their abilities to adhere to various human ligands. All isolates were highly invasive except for ST121. PVL-negative isolates were significantly more invasive than the PVL-positive isolates (p 0.004). Isolates of CC5, CC30 and CC121 were non-cytotoxic, whereas isolates of CC22, CC8, CC15, CC45 and CC88 were very cytotoxic. No statistical association was identified between cell death and methicillin resistance, bacterial PVL status, clonality or patient HIV status. The vast majority of isolates were invasive and induced significant cell death. PVL-negative isolates were more invasive than PVL-positive isolates, while methicillin-resistant isolates were not found to be more invasive or cytotoxic than methicillin-susceptible isolates.

Hybrid nanostructured coating for increased resistance of prosthetic devices to staphylococcal colonization

Prosthetic medical device-associated infections are responsible for significant morbidity and mortality rates. Novel improved materials and surfaces exhibiting inappropriate conditions for microbial development are urgently required in the medical environment. This study reveals the benefit of using natural Mentha piperita essential oil, combined with a 5 nm core/shell nanosystem-improved surface exhibiting anti-adherence and antibiofilm properties. This strategy reveals a dual role of the nano-oil system; on one hand, inhibiting bacterial adherence and, on the other hand, exhibiting bactericidal effect, the core/shell nanosystem is acting as a controlled releasing machine for the essential oil. Our results demonstrate that this dual nanobiosystem is very efficient also for inhibiting biofilm formation, being a good candidate for the design of novel material surfaces used for prosthetic devices.

Human pathogens utilize host extracellular matrix proteins laminin and collagen for adhesion and invasion of the host

Laminin (Ln) and collagen are multifunctional glycoproteins that play an important role in cellular morphogenesis, cell signalling, tissue repair and cell migration. These proteins are ubiquitously present in tissues as a part of the basement membrane (BM), constitute a protective layer around blood capillaries and are included in the extracellular matrix (ECM). As a component of BMs, both Lns and collagen(s), thus function as major mechanical containment molecules that protect tissues from pathogens. Invasive pathogens breach the basal lamina and degrade ECM proteins of interstitial spaces and connective tissues using various ECM-degrading proteases or surface-bound plasminogen and matrix metalloproteinases recruited from the host. Most pathogens associated with the respiratory, gastrointestinal, or urogenital tracts, as well as with the central nervous system or the skin, have the capacity to bind and degrade Lns and collagen(s) in order to adhere to and invade host tissues. In this review, we focus on the adaptability of various pathogens to utilize these ECM proteins as enhancers for adhesion to host tissues or as a targets for degradation in order to breach the cellular barriers. The major pathogens discussed are Streptococcus, Staphylococcus, Pseudomonas, Salmonella, Yersinia, Treponema, Mycobacterium, Clostridium, Listeria, Porphyromonas and Haemophilus; Candida, Aspergillus, Pneumocystis, Cryptococcus and Coccidioides; Acanthamoeba, Trypanosoma and Trichomonas; retrovirus and papilloma virus.

Bacterial inactivation of wound infection in a human skin model by liquid-phase discharge plasma

BACKGROUND

We investigate disinfection of a reconstructed human skin model contaminated with biofilm-formative Staphylococcus aureus employing plasma discharge in liquid.

PRINCIPAL FINDINGS

We observed statistically significant 3.83-log10 (p<0.001) and 1.59-log10 (p<0.05) decreases in colony forming units of adherent S. aureus bacteria and 24 h S. aureus biofilm culture with plasma treatment. Plasma treatment was associated with minimal changes in histological morphology and tissue viability determined by means of MTT assay. Spectral analysis of the plasma discharge indicated the presence of highly reactive atomic oxygen radicals (777 nm and 844 nm) and OH bands in the UV region. The contribution of these and other plasma-generated agents and physical conditions to the reduction in bacterial load are discussed.

CONCLUSIONS

These findings demonstrate the potential of liquid plasma treatment as a potential adjunct therapy for chronic wounds.

Application of suppressive subtractive hybridization to the identification of genetic differences between two Lactococcus garvieae strains showing distinct differences in virulence for rainbow trout and mouse

Lactococcus garvieae is the causative microbial agent of lactococcosis, an important and damaging fish disease in aquaculture. This bacterium has also been isolated from vegetables, milk, cheese, meat and sausages, from cow and buffalo as a mastitis agent, and even from humans, as an opportunistic infectious agent. In this work pathogenicity experiments were performed in rainbow trout and mouse models with strains isolated from human (L. garvieae HF) and rainbow trout (L. garvieae UNIUDO74; henceforth referred to as 074). The mean LD(50) value in rainbow trout obtained for strain 074 was 2.1 × 10(2) ± 84 per fish. High doses of the bacteria caused specific signs of disease as well as histological alterations in mice. In contrast, strain HF did not prove to be pathogenic either for rainbow trout or for mice. Based on these virulence differences, two suppressive subtractive hybridizations were carried out to identify unique genetic sequences present in L. garvieae HF (SSHI) and L. garvieae 074 (SSHII). Differential dot-blot screening of the subtracted libraries allowed the identification of 26 and 13 putative ORFs specific for L. garvieae HF and L. garvieae 074, respectively. Additionally, a PCR-based screening of 12 of the 26 HF-specific putative ORFs and the 13 074-specific ones was conducted to identify their presence/absence in 25 L. garvieae strains isolated from different origins and geographical areas. This study demonstrates the existence of genetic heterogeneity within L. garvieae isolates and provides a more complete picture of the genetic background of this bacterium.

Structural biology of Gram-positive bacterial adhesins

The structural biology of Gram-positive cell surface adhesins is an emerging field of research, whereas Gram-negative pilus assembly and anchoring have been extensively investigated and are well understood. Gram-positive surface proteins known as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) and individual proteins that assemble into long, hair-like organelles known as pili have similar features at the primary sequence level as well as at the tertiary structural level. Some of these conserved features are essential for their transportation from the cytoplasm and for cell wall anchoring. More importantly, the MSCRAMMs and the individual pilins are assembled with building blocks that are variants of structural modules used for human immunoglobulins. MSCRAMMs target the host's extracellular matrix proteins, such as collagen, fibrinogen, and fibronectin, and they have received considerable attention from structural biologists in the last decade, who have primarily been interested in understanding their interactions with host tissue. The recent focus is on the newly discovered pili of Gram-positive bacteria, and in this review, we highlight the advances in understanding of the individual pilus constituents and their associations and stress the similarities between the individual pilins and surface proteins.

Crystallography of gram-positive bacterial adhesins

Both Gram-negative and Gram-positive pathogens display a multitude of proteins and protein assemblies (pili or fimbriae) on their cell surfaces, which are often used for adherence and initiate colonization and pathogenesis. Adhesive proteins known as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), anchored by a specific enzyme called sortase in Gram-positive bacteria, target the host's extracellular matrix proteins (ECM) like collagen, fibrinogen and fibronectin. In the past decade, structural analysis by X-ray crystallography has enhanced our understanding of the interactions between MSCRAMMs and the host ECM by revealing several novel structural features that dictate surface protein assembly and the mode of their adhesion to host tissue. The latest focus is on the recently discovered Gram-positive bacterial pili, assembly of which is assisted by yet another specific sortase. Novel features like inter- and intra-molecular isopeptide bonds that facilitate the stability of the pilins, and intra-molecular donor strand complementation to stabilize the adhesin-target interactions are specific to Gram-positive bacteria. This chapter describes and discusses the common structural details between surface proteins and pilins of Gram-positive bacteria and biological implications emanating from these structures.

Gum arabic modified Fe3O4 nanoparticles cross linked with collagen for isolation of bacteria

Background

Multifunctional magnetic nanoparticles are important class of materials in the field of nanobiotechnology, as it is an emerging area of research for material science and molecular biology researchers. One of the various methods to obtain multifunctional nanomaterials, molecular functionalization by attaching organic functional groups to nanomagnetic materials is an important technique. Recently, functionalized magnetic nanoparticles have been demonstrated to be useful in isolation/detection of dangerous pathogens (bacteria/viruses) for human life. Iron (Fe) based material especially FePt is used in the isolation of ultralow concentrations (< 10² cfu/ml) of bacteria in less time and it has been demonstrated that van-FePt may be used as an alternative fast detection technique with respect to conventional polymerase chain reaction (PCR) method. However, still further improved demonstrations are necessary with interest to biocompatibility and green chemistry. Herein, we report the synthesis of Fe₃O₄ nanoparticles by template medication and its application for the detection/isolation of S. aureus bacteria.

Results

The reduction of anhydrous Iron chloride (FeCl₃) in presence of sodium borohydride and water soluble polyelectrolyte (polydiallyldimethyl ammonium chloride, PDADMAC) produces black precipitates. The X-ray diffraction (XRD), XPS and TEM analysis of the precipitates dried at 373 K demonstrated the formation of nanocrystalline Fe₃O₄. Moreover, scanning electron microscopy (SEM) showed isolated staphylococcous aureus (S. aureus) bacteria at ultralow concentrations using collagen coated gum arabic modified iron oxide nanoparticles (CCGAMION).

Conclusion

We are able to synthesize nanocrystalline Fe₃O₄ and CCGAMION was able to isolate S. aureus bacteria at 8-10 cfu (colony forming units)/ml within ~3 minutes.

Degradation of fibrinogen and collagen by staphopains, cysteine proteases released from Staphylococcus aureus

Staphylococcus aureus is the most frequently isolated pathogen in gram-positive sepsis often complicated by a blood clotting disorder, and is the leading cause of infective endocarditis induced by bacterial destruction of endocardial tissues. The bacterium secretes cysteine proteases referred to as staphopain A (ScpA) and staphopain B (SspB). To investigate virulence activities of staphopains pertinent to clotting disorders and tissue destruction, we examined their effects on collagen, one of the major tissue components, and on plasma clotting. Both staphopains prolonged the partial thromboplastin time of plasma in a dose- and activity-dependent manner, with SspB being threefold more potent than ScpA. Staphopains also prolonged the thrombin time of both plasma and fibrinogen, indicating that these enzymes can cause impaired plasma clotting through fibrinogen degradation. Whereas SspB cleaved the fibrinogen Aα-chain at the C-terminal region very efficiently, ScpA degraded it rather slowly. This explains the superior ability of the former enzyme to impair fibrinogen clottability. Enzymically active staphopains, at concentrations as low as 10 nM, degraded collagen with comparable efficiency. These results show novel virulence activities of staphopains in degrading fibrinogen and collagen, and suggest an involvement of staphopains in the clotting impairment and tissue destruction caused by staphylococcal infection.

Bacterial keratitis: perspective on epidemiology, clinico-pathogenesis, diagnosis and treatment

Bacterial keratitis is an acute or chronic, transient or recurrent infection of the cornea with varying predilection for anatomical and topographical parts of the cornea like marginal or central. It is a potentially sight-threatening corneal infection in humans that is generally found in eyes with predisposing elements, the most common of which is contact lens wear. The epidemiological data reveals the universal occurrence of this disease. With advances in the understanding of its pathogenesis, laboratory investigations like immunohistochemistry, fluorescent microscopy, enzyme immunoassays and molecular biology, and the availability of fourth generation antibiotics, the overall visual outcome in bacterial keratitis has improved with time. Particular attention should be given to this condition as it can progress very rapidly with complete corneal destruction occurring within 24-48 hours. Early diagnosis, which is primarily clinical and substantiated largely by microbiological data, and prompt treatment are needed to minimise the possibility of permanent visual loss and reduce structural damage to the cornea.

Surface-associated activation of plasminogen on gram-positive bacteria. Effect of plasmin on the adherence of Staphylococcus aureus

In this article we review a novel type of plasminogen activation on staphylococcal and streptococcal cells. The activation mechanism implies a specific binding of glu-plasminogen to bacterial surface via the lysine-binding sites of plasminogen. Association of plasminogen with bacterial surfaces greatly enhances the t-PA mediated activation which takes place only poorly in solution. The end product, surface-associated plasmin, is enzymatically active, protected against high molecular weight plasmin inhibitors and capable of converting itself from glu-plasmin to the lys-form. The modification is associated with an increased affinity of the bound lys-plasmin towards the binding molecules on bacterial surface. This novel way of retaining plasmin on the surface may be important for the bacteria to invade and penetrate surrounding tissues. Our data on the effect of plasmin on staphylococcal adherence indicate that plasmin is not very effective in cleaning bacteria from surfaces coated with extracellular matrix components, fibronectin and fibrinogen.

An acute osteomyelitis model in traumatized rat tibiae involving sand as a foreign body, thermal injury, and bimicrobial contamination

The multfactorial nature of bone injuries in modern warfare and emergency trauma patients warrants enhancement of existing models. To develop a more appropriate model, rat tibiae (n = 195) were mechanically injured, divided into 2 groups (with or without thermal injury), and contaminated with a range of Staphylococcus aureus (Cowan 1) inocula. In some experiments, S. aureus inocula also contained Escherichia coli or foreign bodies (sand or soil). The primary outcome measure was the amount of S. aureus remaining in the tibia (tibial bacterial load) 24 h after contamination, reported as log10 cfu/g bone. S. aureus showed ID50 and ID95 values of 72 and 977 cfu, respectively. Values were lower than seen previously by using S. aureus strain SMH. S. aureus tibial bacterial loads were higher in tibiae with mechanical and thermal injury (log10 4.15 +/- 0.27 cfu/g) versus mechanical injury alone (log10 3.1 +/- 0.47 cfu/g, P = 0.028). The addition of E. coli to the S. aureus inoculum had no effect on tibial bacterial loads (S. aureus only, log10 4.24 +/- 0.92 cfu/g; S. aureus + E. coli, log10 4.1 +/- 1.0 cfu/g, P = 0.74). Sand, added as a foreign body, increased tibial bacterial load. Combined mechanical and thermal trauma of the tibia is associated with increased S. aureus tibial bacterial loads, increasing the risk of acute osteomyelitis. Understanding the interplay of mechanical and thermal injuries, bimicrobial contamination, and foreign bodies may improve our understanding of traumatic bone injuries and the pathogenesis of osteomyelitis.

Prevalence of genes encoding extracellular virulence factors among meticillin-resistant Staphylococcus aureus isolates from the University Hospital, Olomouc, Czech Republic

A rather fast and complicated progression of an infection caused by some strains of Staphylococcus aureus could be associated with the expression and co-action of virulence factor complexes in these strains. This study screened the antibiotic susceptibility and prevalence of virulence markers in isolates of meticillin-resistant S. aureus (MRSA) obtained from patients hospitalized at the University Hospital in Olomouc, Czech Republic. A total of 100 isolates was screened for 13 genes encoding extracellular virulence determinants (tst, pvl, eta, etb, sea, seb, sec, sed, see, seg, seh, sei and sej) and for their distribution in sample types. Eighty-nine isolates were positive for at least one of the genes. Genes for etb, pvl, see and seh were not detected in any of the MRSA isolates. No statistically significant differences in the occurrence of the determinants studied among sample types were found.

The N-terminal A domain of Staphylococcus aureus fibronectin-binding protein A binds to tropoelastin

Staphylococcus aureus is an important human pathogen. Its virulence factors include a variety of MSCRAMMs (microbial surface component recognizing adhesive matrix molecules), each capable of binding specifically to the host extracellular matrix. The fibronectin-binding protein, FnBPA, has been shown previously to bind immobilized fibronectin, fibrinogen, and alpha-elastin peptides. Here we show that region A of FnBPA (rAFnBPA) binds to recombinant human tropoelastin. Binding occurs to three separate truncates of tropoelastin, encompassing domains 2-18, 17-27, and 27-36, signifying that the interaction occurs at multiple sites. The greatest affinity was for the N-terminal truncate. We observed a pH dependency for the rAFnBPA-tropoelastin interaction with strong, nonsaturable binding at low pH. The interaction ceased at higher pH. These data support a model of surface-surface interactions between the negative charges present on rAFnBPA and the positive lysines of tropoelastin. A protein lacking the negatively charged C-terminal fibronectin-binding motif of the A domain of FnBPA and another construct lacking subdomain N1 were both capable of binding immobilized tropoelastin with a lower affinity. The binding properties of five site-directed mutants of rAFnBPA were compared with wild-type rAFnBPA. There was no decreased affinity for immobilized tropoelastin, in contrast to the defective binding of these mutants to alpha-elastin and fibrinogen. The data indicate novel interactions between tropoelastin and FnBPA that include the use of surface charges. These results demonstrate that FnBPA is capable of directly binding tropoelastin prior to its incorporation into elastin.

Surface Adhesins of Staphylococcus aureus

An important facet in the interaction between Staphylococcus aureus and its host is the ability of the bacterium to adhere to human extracellular matrix components and serum proteins. In order to colonise the host and disseminate, it uses a wide range of strategies, the molecular and genetic basis of which are multifactorial, with extensive functional overlap between adhesins. Here, we describe the current knowledge of the molecular features of the adhesive components of S. aureus, mechanisms of adhesion and the impact that these have on host-pathogen interaction.

Quantifying the temporal expression of the Staphylococcus aureus collagen adhesin

The initial event in the pathogeneis of most Staphylococcus aureus infections is attachment to biological substrates in vivo using specific protein-protein interactions. We previously quantified the temporal expression of the collagen adhesin (CNA) on S. aureus Phillips and demonstrated that dynamic adhesin capacity to collagen is strongly influenced by the adhesin density. However, most strains of S. aureus express an extensive amount of Protein A on the surface, presenting a complication when using immunofluorescence to quantify specific surface adhesins. In this study, an improved adhesin quantification method is presented that accommodates variable surface Protein A levels. This method was used to examine the temporal expression of CNA on six S. aureus strains. Collagen adhesin levels varied with growth phase and strain, ranging from 1096 to 8950 copies per cell. Five of the six strains exhibited a temporal expression pattern similar to that previously reported for S. aureus Phillips.

Attachment of bacteria to beef from steam-pasteurized carcasses

The extent to which a bacterial cocktail containing equal numbers of Pseudomonas fragi NCTC 10689, Listeria monocytogenes BL5/2, Salmonella Typhimurium LT2, and Escherichia coli JM 109 attached to loin surface cuts (7 by 5 cm) derived from steam-pasteurized beef carcasses has been evaluated. The extent of attachment was categorized as loosely attached (removed by rinsing), firmly attached (released by stomaching), and irreversibly bound. No significant difference (P > 0.10) in the attachment of bacteria to steam-pasteurized carcasses was found compared with control loin samples that had received no treatment. No significant difference (P > 0.05) was also found in the attachment strength between the different bacterial species tested. Most bacteria inoculated onto the loin cuts were reversibly bound, since they had been removed by rinsing and stomaching. The irreversible attachment of bacteria to loin cuts was found to vary significantly (P < 0.01) among the different carcass sets used but was independent of whether the carcass had undergone steam pasteurization treatment. Use of a bioluminescent strain of E. coli showed that cells bound preferentially to cut edges and convoluted areas on the loin surface and could not be removed by rinsing. The possible mechanisms of bacterial attachment and the suitability of steam pasteurization to remove contamination incurred during slaughter are discussed.

Monoclonal antibodies to CNA, a collagen-binding microbial surface component recognizing adhesive matrix molecules, detach Staphylococcus aureus from a collagen substrate

Previous studies showed that Staphylococcus aureus expresses a collagen-binding MSCRAMM (Microbial Surface Component Recognizing Adhesive Matrix Molecules), CNA, that is necessary and sufficient for S. aureus cells to adhere to cartilage and is a virulence factor in experimental septic arthritis. We have now used a monoclonal antibody (mAb) approach to further analyze the structure and function of CNA. 22 mAbs raised against the minimal ligand binding domain, CNA-(151-318), were shown to bind to the MSCRAMM with similar affinity. All mAbs appear to recognize conformation-dependent epitopes that were mapped throughout the CNA-(151-318) domain using a chimeric strategy where segments of CNA are grafted on ACE, a structurally related MSCRAMM from Enterococcus faecalis. These mAbs were able to inhibit (125)I-collagen binding to CNA-(151-318) as well as to intact S. aureus cells. They also interfered with the attachment of bacteria to collagen substrates. Furthermore, some of the mAbs could effectively displace (125)I-collagen bound to the bacteria. These displacing mAbs were also able to detach bacteria that had adhered to a collagen substrate in a preincubation, raising the possibility that some of the mAbs may be used as therapeutic agents.

Quantification of Staphylococcus aureus cell surface adhesins using flow cytometry

The initiation of many infectious diseases involves specific adhesion of bacteria to host tissue proteins and carbohydrates. Staphylococcus aureus is known to bind specifically to several proteins in the extracellular matrix (ECM). We report the quantification of the collagen and fibronectin adhesin densities on the staphylococcal surface using flow cytometry. Our results are in agreement with previous reports on the transcription of the respective genes and demonstrate different patterns of temporal expression for the two adhesins in the strains studied. We demonstrate a convenient technique for quantification of bacterial adhesins that can be used in studies aimed at characterization of bacterial adhesion to ECM components and understanding expression of adhesins during the course of an infection.

Enterococcus faecalis adhesin, ace, mediates attachment to extracellular matrix proteins collagen type IV and laminin as well as collagen type I

Adhesin-mediated binding to extracellular matrix (ECM) proteins is thought to be a crucial step in the pathogenic process of many bacterial infections. We have previously reported conditional adherence of most Enterococcus faecalis isolates, after growth at 46 degrees C, to ECM proteins collagen types I and IV and laminin; identified an E. faecalis-specific gene, ace, whose encoded protein has characteristics of a bacterial adhesin; and implicated Ace in binding to collagen type I. In this study, we constructed an ace disruption mutant from E. faecalis strain OG1RF that showed marked reduction in adherence to collagen types I and IV and laminin when compared to the parental OG1RF strain after growth at 46 degrees C. Polyclonal immune serum raised against the OG1RF-derived recombinant Ace A domain reacted with a single approximately 105-kDa band of mutanolysin extracts from OG1RF grown at 46 degrees C, while no band was detected in extracts from OG1RF grown at 37 degrees C, nor from the OG1RF ace mutant grown at 37 or 46 degrees C. IgGs purified from the anti-Ace A immune serum inhibited adherence of 46 degrees C-grown E. faecalis OG1RF to immobilized collagen type IV and laminin as well as collagen type I, at a concentration as low as 1 microg/ml, and also inhibited the 46 degrees C-evoked adherence of two clinical isolates tested. We also showed in vitro interaction of collagen type IV with Ace from OG1RF mutanolysin extracts on a far-Western blot. Binding of recombinant Ace A to immobilized collagen types I and IV and laminin was demonstrated in an enzyme-linked immunosorbent assay and was shown to be concentration dependent. These results indicate that Ace A mediates the conditional binding of E. faecalis OG1RF to collagen type IV and laminin in addition to collagen type I.

Functional mapping of the Yersinia enterocolitica adhesin YadA. Identification Of eight NSVAIG - S motifs in the amino-terminal half of the protein involved in collagen binding

The virulence plasmid-encoded YadA of Yersinia enterocolitica serotype O:3 is a 430-amino-acid outer membrane protein, synthesized with a 25-amino-acid signal peptide. YadA forms homotrimeric surface structures that function as adhesin between bacteria and collagen as well as other host proteins. The structure-function relationships of YadA were studied, and the collagen-binding determinants of YadA were located to its amino-terminal half. Collagen did not bind to any of the overlapping 16-mer YadA peptides, indicating that the collagen binding site of YadA is conformational. Epitope mapping of YadA identified 12 linear antigenic epitopes altogether. Seven epitopes were uniquely recognized by an anti-YadA antiserum able to inhibit collagen binding. Four of these epitopes shared a motif NSVAIG-S that is repeated eight times within the N-terminal half of YadA. Site-directed mutagenesis showed that these motifs are absolutely required for YadA-mediated collagen binding, revealing a novel type of collagen-binding mechanism.

A microscopic method to visualize Escherichia coli interaction with beef muscle

The genetic determinant for enhanced green fluorescent protein (EGFP) was introduced into Escherichia coli JM109 (ATCC 53323) and E. coli O157:H7 (ATCC 43895) on plasmid EGFP. The expression of EGFP did not change the growth kinetics or surface properties tested (hydrophobicity and electrophoretic mobility). Microscope slides were modified to allow for optimal viewing of thick meat samples with an inverted microscope. Two fluorescent dyes, nile red and Cy3 were used to stain for lipid and protein portions of beef muscle, respectively. Laser scanning confocal microscopy was used to observe interaction of the EGFP-expressing E. coli strains and the fluorescently stained muscle components without changing the spatial and temporal environment of the organisms.

Novel fold and assembly of the repetitive B region of the Staphylococcus aureus collagen-binding surface protein

BACKGROUND

[corrected] The Staphylococcus aureus collagen-binding protein Cna mediates bacterial adherence to collagen. The primary sequence of Cna has a non-repetitive collagen-binding A region, followed by the repetitive B region. The B region has one to four 23 kDa repeat units (B(1)-B(4)), depending on the strain of origin. The affinity of the A region for collagen is independent of the B region. However, the B repeat units have been suggested to serve as a 'stalk' that projects the A region from the bacterial surface and thus facilitate bacterial adherence to collagen. To understand the biological role of these B-region repeats we determined their three-dimensional structure.

RESULTS

B(1) has two domains (D(1) and D(2)) placed side-by-side. D(1) and D(2) have similar secondary structure and exhibit a unique fold that resembles but is the inverse of the immunoglobulin-like (IgG-like) domains. Comparison with similar immunoglobulin superfamily (IgSF) structures shows novel packing arrangements between the D(1) and D(2) domains. In the B(1)B(2) crystal structure, an omission of a single glycine residue in the D(2)-D(3) linker loop, compared to the D(1)-D(2) and D(3)-D(4) linker loops, resulted in projection of the D(3) and D(4) in a spatially new orientation. We also present a model for B(1)B(2)B(3)B(4).

CONCLUSIONS

The B region of the Cna collagen adhesin has a novel fold that is reminiscent of but is inverse in nature to the IgG fold. This B region assembly could effectively provide the needed flexibility and stability for presenting the ligand binding A region away from the bacterial cell surface.

Role of bacterial association and penetration on destruction of Escherichia coli O157:H7 in beef tissue by high pH

This study was undertaken to determine if association with collagen enables Escherichia coli O157:H7 to resist high-pH treatments and to determine the effects of high pH on the survival of E. coli O157:H7 within different layers of beef tissue. E. coli O157:H7 was inoculated onto purified bovine type I collagen on 12-mm2 circular glass coverslips, plain 12-mm2 circular glass coverslips (control), and 12-mm2 irradiated (cobalt-60) lean beef tissue. The rates of destruction of E. coli O157:H7 inoculated on coverslips in pH 10.5 NaHCO3-NaOH buffer at 35 degrees C were determined at various sampling times. E. coli O157:H7 cells associated with collagen and treated in the same manner were also examined using scanning electron microscopy to determine if association with collagen enabled the organism to resist high-pH treatments. The inoculated tissue was treated in pH 13.0 NaHCO3-NaOH buffer at 25 degrees C, and penetrating cells of E. coli O157:H7 were recovered using a cryostat technique. There was no significant difference (P < 0.05) between the rates of destruction of collagen-associated E. coli O157:H7 and non-collagen-associated E. coli O157:H7 following exposure to high-pH treatments. Scanning electron micrographs showed that collagen-associated E. coli O157:H7 cells appeared physically damaged by exposure to high-pH treatments, and association of E. coli O157:H7 to collagen did not increase the resistance of the organism to destruction by high-pH rinses. No significant differences were seen between 20 ml of NaHCO3-NaOH buffer at pH 13.0 (treatment) and 20 ml of distilled water at pH 7.0 (control) when E. coli O157:H7 cells were recovered in beef tissue at depths of up to 2,000 microm (P < 0.05). The ability of E. coli O157:H7 to penetrate beef tissue may be an important factor in reducing the effectiveness of high-pH treatments in killing this organism on beef tissue. This finding should be considered in the future when designing treatments to decontaminate beef carcasses.

Isolation of Enterococcus faecalis clinical isolates that efficiently adhere to human bladder carcinoma T24 cells and inhibition of adhesion by fibronectin and trypsin treatment

The adherence of Enterococcus faecalis strains to human T24 cells was examined by scanning electron microscopy. Five highly adhesive strains were identified from 30 strains isolated from the urine of patients with urinary tract infections. No efficiently adhesive strains were found among the 30 strains isolated from the feces of healthy students. The five isolated strains also adhered efficiently to human bladder epithelial cells. Analysis of restriction endonuclease-digested plasmid DNAs and chromosome DNAs showed that the five strains were different strains isolated from different patients. The adhesiveness of these strains was inhibited by treatment with fibronectin or trypsin, implying that a specific protein (adhesin) on the bacterial cell surface mediates adherence to fibronectin on the host cell surfaces, and the adhesin differs from the reported adhesins.

Inhibition of Staphylococcus aureus adherence to collagen under dynamic conditions

Staphylococcus aureus is the most common etiological agent of bacterial arthritis and acute osteomyelitis and has been shown to bind to type II collagen under static and dynamic conditions. We have previously reported the effect of shear on the adhesion of S. aureus Phillips to collagen and found that this process is shear dependent (Z. Li, M. Höök, J. M. Patti, and J. M. Ross, Ann. Biomed. Eng. 24[Suppl. 1]:S-55). In this study, we used recombinant collagen adhesin fragments as well as polyclonal antibodies generated against adhesin fragments in attempts to inhibit bacterial adhesion. A parallel-plate flow chamber was used in a dynamic adhesion assay, and quantification of adhesion was accomplished by phase contrast video microscopy coupled with digital image processing. We report that both recombinant fragments studied, M19 and M55, and both polyclonal antibodies studied, alpha-M17 and alpha-M55, inhibit adhesion to varying degrees and that these processes are shear dependent. The M55 peptide and alpha-M55 cause much higher levels of inhibition than M19 and alpha-M17, respectively, at all wall shear rates studied. Our results demonstrate the importance of using a dynamic system in the assessment of inhibitory strategies and suggest the possible use of M55 and alpha-M55 in clinical applications to prevent infections caused by S. aureus adhesion to collagen.

Characterization of the elastin binding domain in the cell-surface 25-kDa elastin-binding protein of staphylococcus aureus (EbpS)

Our previous studies have established that a cell-surface 25-kDa elastin-binding protein of Staphylococcus aureus (EbpS) mediates binding of this pathogen to the extracellular matrix protein elastin. Results from binding assays examining the activity of various EbpS fragments suggested that the elastin recognition domain is contained within the first 59 amino acids. In this report, we have used functional analyses with synthetic peptides and recombinant truncated forms of EbpS to localize the elastin binding domain to a 21-amino acid region contained within residues 14-34 of EbpS. Further evidence for the importance of this domain was obtained by demonstrating that the inhibitory activity of anti-EbpS antibodies on staphylococcal elastin binding was neutralized when these antibodies were pre-absorbed with a truncated recombinant EbpS construct containing residues 1-34. Overlapping synthetic peptides corresponding to EbpS residues 14-36 were then generated and tested for elastin binding activity to define further the elastin binding domain, and results from these studies showed that sequences spanning amino acids Gln14-Asp23, Asp17-Asp23, and Thr18-Glu34 inhibit binding of Staphylococcus aureus to elastin. Our analyses indicate that the hexameric sequence Thr18-Asn-Ser-His-Gln-Asp23 is the minimal sequence common to all active synthetic peptides, proteolytic fragments, and recombinant constructs of EbpS. Furthermore, substitution of Asp23 with Asn abrogated the blocking activity of the synthetic peptides, demonstrating the requirement for a charged amino acid at this location. The composite data indicate that staphylococcal elastin binding is mediated by a discrete domain defined by short peptide sequences in the amino-terminal extracellular region of EbpS.

Receptins: a novel term for an expanding spectrum of natural and engineered microbial proteins with binding properties for mammalian proteins

A new term 'receptin', derived from recipere (lat.), is proposed to denote microbial binding proteins that interact with mammalian target proteins. An example of such a 'receptin' is staphyloccocal protein A which binds to the Fc part of many mammalian immunoglobulins. Several other types of 'receptins' are listed. This term may easily be distinguished from the similar term 'receptor', describing a binding site on a cell surface, mostly eukaryotic, where a secondary effect is induced inside the cell upon binding to a ligand. A receptin, however, does not necessarily have to induce a secondary event. Receptins include so called MSCRAMMs, adhesins, and also engineered receptins, affibodies, and engineered ligands. It denotes any protein of microbial origin, cell-bound or soluble, which can bind to a mammalian protein. It fulfills the need for an umbrella terminology for a large group of binding structures. In contrast, the term 'lectin' represents a group of proteins with affinity for carbohydrate structures. The new term 'receptin' includes a number of key microbial proteins involved in host-parasite interactions and in virulence. Some receptins are promising vaccine candidates.

Biomaterials and cardiovascular devices

In the field of cardiovascular surgery there is presently a lack of biomaterials possessing essential characteristics of the native tissue or organ which is to be replaced. This paper describes various biomaterials that have been introduced into the circulatory system and the complex reactions that subsequently occur. The risk of infection is also discussed as well as prevention and treatment regimes that can be used. Examples of future biomaterial development are outlined in an attempt to achieve biocompatibility.

Conditional adherence of Enterococcus faecalis to extracellular matrix proteins

The adherence of 44 clinical isolates of Enterococcus faecalis, a common cause of endocarditis, and 13 Enterococcus faecium to substrates of six extracellular matrix (ECM) proteins was examined using 35S-labeled bacteria. One E. faecalis strain, isolated from a patient with endocarditis, adhered to collagen types I and IV and another E. faecalis strain adhered to laminin and to collagen types I and IV. However, most isolates showed little adherence ( < 5% of added cells adhered) when grown at 37 degrees C regardless of their source (endocarditis, urine or fecal sample). When grown at 46 degrees C (but not when grown in CO2 or nutrient limited media), most isolates of E. faecalis increased their adherence to immobilized laminin, collagen types I and IV but not to fibronectin, fibrinogen or bovine serum albumin, whereas none of the E. faecium increased adherence when grown at 46 degrees C or 50 degrees C. The adherence of E. faecalis was eliminated by digestion with trypsin, suggesting that a protein is somehow important, directly or indirectly, for adherence to occur. Pre-incubation of bacteria with soluble collagen types I and IV inhibited the adherence to these ECM proteins. These results demonstrate that in E. faecalis, adherence to ECM proteins is produced during routine in vitro growth conditions by occasional isolates and can be produced during certain stressful growth conditions by others. Whether this adherence relates to the propensity of E. faecalis to cause endocarditis remains to be determined.

Virulence factors of Staphylococcus aureus in the pathogenesis of endocarditis. A comparative study of clinical isolates

It is now generally accepted that adherence of microorganisms to various components of cardiac valve surfaces or vegetation lodging on the heart valves is an important early event in the pathogenesis of infective endocarditis. 120 clinical isolates of S. aureus obtained from patients with endocarditis and wound infections and from nasopharyngeal carriers were quantitatively analysed in vitro for their ability to bind to fibronectin and to produce protein A and alpha-toxin. Both cell-bound and extracellular protein A were measured and alpha-toxin was determined as antigen and as haemolytic activity. The highest fibronectin binding ability was found in carrier strains while no significant differences between strains were observed regarding the production of protein A. Strains isolated from patients with endocarditis produced significantly lower amounts of alpha-toxin than did strains from the other two groups. An inverse relationship between the production of protein A and of alpha-toxin was noticed in the material. Animal passage of five strains in an experimental endocarditis model showed a good reproducibility of the test systems and one strain was upregulated in its fibronectin binding ability and in alpha-toxin production. These in vitro results indicate that the fibronectin binding ability is not the decisive adherence factor and question the role of alpha-toxin as a virulence factor in endocarditis.

Binding of complement subcomponent C1q to Streptococcus pyogenes: evidence for interactions with the M5 and FcRA76 proteins

Binding of C1q, the first component of the complement system, to some human pathogens has been earlier reported. In the present study, direct binding of C1q to group A streptococci (GAS) of various serotypes as well as some other Gram-positive and Gram-negative species was demonstrated. The interaction between C1q and GAS was investigated more in detail. In hot neutral extracts of a number of GAS strains two components of 64 and 52 kDa, respectively, bound C1q; alkaline and SDS extracts yielded the 52 kDa component as the main C1q-binding substance. Trypsin treatment of the SDS extracts of two GAS strains suggested the C1q-binding component(s) to be of protein nature. C1q-binding material purified from the SDS extract of an avirulent strain, type T27, was separated in 12% SDS-PAGE and probed in Western blot with human C1q and fibrinogen, conjugated to horse radish peroxidase (HRP) as well as rabbit IgG antibodies complexed to HRP (PAP system). The 52 kDa component was non-reactive with fibrinogen or rabbit IgG. However, C1q-binding components purified from the alkaline extracts of two M-positive strains revealed strong binding of either fibrinogen (type M5) or both fibrinogen and rabbit IgG (type M76); the molecular mass of these components. 55 kDa and 43-40 kDa, respectively, was in agreement with the reported molecular mass of the M5 and FcRA76 proteins. Our findings suggest that C1q may interact with GAS through certain M-family proteins as well as by a so far unidentified surface factor of protein nature occurring in most GAS strains. The involvement of M-family proteins, regarded as virulence factors of these organisms, may suggest the interaction of GAS with C1q as biologically important.

Staphylococcus aureus causing osteomyelitis binds to a nonapeptide sequence in bone sialoprotein

Bone sialoprotein is a glycoprotein of the bone and dentine extracellular matrix. This protein consists of 320 amino acids, of which 25% are glutamic and aspartic acid residues. Sialic acid, containing oligosaccharides and tyrosine sulphate residues, supplies additional polyanionic properties. Staphylococcal cells, isolated from patients suffering from infection of bone tissue, bind the bone-derived sialoprotein, an interaction which is specifically inhibited by the recombinant bone sialoprotein core protein. We have previously shown that the 150 N-terminal amino acid residues of bone sialoprotein are responsible for the binding to staphylococcal cells. By using recombinant deleted variants of bone sialoprotein and synthetic peptides, we have now localized the staphylococcal binding site to less than 10 residues within the N-terminal part of the protein.

Structure of the collagen-binding domain from a Staphylococcus aureus adhesin

The crystal structure of the recombinant 19,000 M(r) binding domain from the Staphylococcus aureus collagen adhesin has been determined at 2 A resolution. The domain fold is a jelly-roll, composed of two antiparallel beta-sheets and two short alpha-helices. Triple-helical collagen model probes were used in a systematic docking search to identify the collagen-binding site. A groove on beta-sheet I exhibited the best surface complementarity to the collagen probes. This site partially overlaps with the peptide sequence previously shown to be critical for collagen binding. Recombinant proteins containing single amino acid mutations designed to disrupt the surface of the putative binding site exhibited significantly lower affinities for collagen. Here we present a structural perspective for the mode of collagen binding by a bacterial surface protein.

Molecular cloning and expression of the gene for elastin-binding protein (ebpS) in Staphylococcus aureus

Interactions between staphylococci and components of the extracellular matrix mediate attachment of the bacteria to host tissues and organs and define an important mechanism leading to colonization, invasion, and formation of metastatic abscesses. We have previously demonstrated a specific binding interaction between Staphylococcus aureus and elastin, one of the major protein components of the extracellular matrix. Available evidence suggests that this association is mediated by a 25-kDa elastin-binding protein on the surface of S. aureus (EbpS). To study the molecular structure and function of EbpS, the gene encoding EbpS was cloned, sequenced, and expressed in Escherichia coli. DNA sequence data indicate that the ebpS open reading frame consists of 606 base pairs and encodes a novel polypeptide with a predicted molecular mass of 23,345 daltons and pI of 4.9. A polyclonal antibody raised against recombinant EbpS interacted with the native 25-kDa cell surface EbpS and inhibited staphylococcal elastin binding. Furthermore, recombinant EbpS bound specifically to immobilized elastin and inhibited binding of S. aureus to elastin. A degradation product of recombinant EbpS lacking the first 59 amino acids of the molecule and a C-terminal fragment of CNBr-cleaved recombinant EbpS, however, did not interact with elastin. Together, these results confirm that EbpS is the cell surface molecule mediating binding of S. aureus to elastin. The inability of truncated forms of recombinant EbpS to bind to elastin suggests that the elastin binding site in EbpS is contained in the first 59 amino acids of the molecule.

Purification and characterisation of a plasmin-sensitive surface protein of Staphylococcus aureus

Certain methicillin-resistant Staphylococcus aureus strains contain a 230-kDa cell-wall protein which is not present on the surface of other staphylococci. The presence of this 230-kDa protein is associated with a negative test result in commercial assays designed to detect fibrinogen-binding proteins and/or protein A on the staphylococcal surface. We have purified and partially characterised the 230-kDa protein from a lysostaphin digest of a non-agglutinating methicillin-resistant S. aureus strain. Partial amino acid sequence data obtained from the purified protein did not reveal any significant similarities to known proteins which indicates that the protein is novel. The 230-kDa protein was very sensitive to proteolysis; soluble plasmin, or plasmin formed on the bacterial-cell surface, rapidly degraded the 230-kDa protein to a 175-kDa form. The finding that the 230-kDa protein bound to lectins allowed its purification by affinity chromatography on immobilised wheat germ agglutinin. Furthermore, the degradation of the 230-kDa protein was associated with an increased adherence of non-agglutinating methicillin-resistant S. aureus cells to solid-phase fibronectin, fibrinogen or IgG.

Role of YadA-mediated collagen binding in arthritogenicity of Yersinia enterocolitica serotype O:8: experimental studies with rats

Outer membrane protein YadA, Yersinia adhesin, is one of the plasmid-encoded virulence factors of yersiniae. YadA protects bacteria against host defense through several different mechanisms. One important role of YadA is to mediate binding to several collagen types. Our recent study revealed that a yadA null mutant of Yersinia enterocolitica serotype O:8 has a drastically reduced arthritogenic capacity when injected intravenously into Lewis rats. To further characterize the arthritogenic role of YadA, we repeated the rat experiments with strain Y. enterocolitica O:8/pYV082; this strain expresses a YadA deletion derivative lacking 22 amino acids from the amino-terminal hydrophobic region and does not bind to collagen. Y. enterocolitica O:8/pYV082 induced arthritis in 5 to 14% of rats inoculated with arthritogenic doses, whereas the arthritis incidence with the wild-type parent strain was 65%. The parent strain was slightly more virulent than Y. enterocolitica O:8/pYV082, as determined by rat mortality. It also frequently induced skin abscesses, whereas Y. enterocolitica O:8/pYV082 did not. Infection kinetics in spleen and mesenteric lymph nodes were about the same with both of the bacterial strains used, and the same was true of the Yersinia-specific antibody response. Altogether, these results suggest that YadA-mediated collagen binding contributes to the arthritogenicity of Y. enterocolitica O:8.

Isolation and characterisation of a vitronectin-binding surface protein from Staphylococcus aureus

In a previous study we demonstrated that cells of Staphylococcus aureus strain V8 bind 125I-labelled vitronectin in a receptor-ligand type of interaction, and a protein having a molecular mass of 60 kDa was identified as a putative high-affinity staphylococcal vitronectin-binding protein (Liang, O.D. et al. (1993) Biochim. Biophys. Acta 1225, 57-63). In the present communication we report on the isolation and preliminary characterisation of the 60 kDa vitronectin-binding protein. The bacterial cell surface proteins were released by stirring bacteria with 1 M LiCl at 37 degrees C for 2 h and separated on an FPLC Mono-Q column with a gradient of 0-0.5 M NaCl in 20 mM Tris buffer at pH 9.0. Fractions containing vitronectin-binding activity, assayed on microtiter plates with immobilised human vitronectin, were collected and SDS-PAGE analysis showed the content to be a single protein band at the 60 kDa position. In Western blot experiments the protein transblotted onto nitrocellulose membranes could bind soluble vitronectin. Its amino-terminal amino acid sequences showed a striking similarity with those of a 60 kDa heparan sulfate-binding protein from the same staphylococcal strain (Liang, O.D. et al. (1992) Infect. Immun. 60, 899-906), suggesting that they are identical molecules. This was supported by ligand blotting experiments where both vitronectin and heparan sulfate were shown to bind to the same protein band in parallel strips.

Isolation and characterization of a novel collagen-binding protein from Streptococcus pyogenes strain 6414

In this report we have analyzed the binding of collagen to Streptococcus pyogenes strain 6414. This binding was rapid, specific, and involved a limited number of receptor molecules (11,600 copies per cell). When the proteins in a streptococcal lysate were blotted onto a nitrocellulose filter and probed with 125I-labeled collagen, a prominent collagen-binding protein of 57 kDa was identified as well as minor 130-150-kDa components. The major 57-kDa protein was isolated by affinity chromatography on collagen-Sepharose followed by gel filtration chromatography. The 57-kDa protein purified from S. pyogenes was used to raise a monospecific antibody which also reacted with a collagen-binding protein of similar molecular size isolated from Streptococcus zooepidemicus. The two collagen-binding proteins from streptococci have a similar amino acid composition and isoelectric points. Isolated collagen-binding protein was specifically recognized by 125I-collagen in a solid-phase binding assay and displayed an affinity for the ligand quite similar to that exhibited by intact bacteria (Kd = 3.1 versus 3.5 x 10(-9) M, respectively). Surface-labeled bacteria attached to microtiter wells coated with different collagen types and the 57-kDa protein blocked the adhesion to collagen substrate. We propose that the 57-kDa protein is an adhesin involved in the attachment of streptococci to host tissues.

Vaccination with Staphylococcus aureus fibrinogen binding proteins (FgBPs) reduces colonisation of S. aureus in a mouse mastitis model

A mouse mastitis model was used to study the effect of vaccination with fibrinogen binding proteins and collagen binding protein from Staphylococcus aureus against challenge infection with S. aureus. The mice vaccinated with fibrinogen binding proteins showed reduced rates of mastitis compared with controls. Gross examination of challenged mammary glands of mice showed that the glands of mice immunized with fibrinogen binding proteins developed mild intramammary infection or had no pathological changes compared with glands from control mice. Histopathological examination of tissue sections from challenged glands showed that most glands from mice vaccinated with fibrinogen binding protein developed disseminated necrosis or had no pathological changes. A significantly reduced number of bacteria could be recovered in the glands from mice immunized with fibrinogen binding proteins as compared with controls. In a similar study, immunization of mice with collagen binding protein did not induce protection against challenge infection with S. aureus.

Binding of host-associated treponeme proteins to collagens and laminin: a possible mechanism of spirochetal adherence to host tissues

The polypeptides of seven strains of human treponemes were investigated by immunoblot analysis for their binding to the human placental collagens and laminin. Of the treponemal polypeptides, eleven polypeptides, 45-kDa, 49-kDa, and 62-kDa polypeptides from T. pallidum ATCC 27087, a 48-kDa polypeptide from T. phagedenis biotype Reiter, 51-kDa and 53-kDa polypeptides from T. vincentii ATCC 35580, 30-kDa, 53-kDa and 63-kDa polypeptides from T. socranskii subsp. buccale ATCC 35534, a 52-kDa polypeptide from T. denticola ATCC 35405, and a 53-kDa polypeptide from T. denticola ATCC 33520 possessed an ability to bind to the laminin, type I, III, IV, or V collagen. An intermediate-sized human oral isolate strain G7201 did not possess any laminin- or collagen-binding polypeptides. Immunoelectron microscopy using intact treponemal cells with a single collagen-binding polypeptide and the corresponding antisera demonstrated that the 51-kDa and 53-kDa polypeptides from T. vincentii, the 53-kDa polypeptide from T. socranskii subsp. buccale ATCC 35534 and the 52-kDa polypeptide from T. denticola ATCC 35405, were outer envelope proteins.

Vaccination against Staphylococcus aureus mastitis: immunological response of mice vaccinated with fibronectin-binding protein (FnBP-A) to challenge with S. aureus

Mice were immunized with fusion proteins encompassing the fibronectin-binding domain of a staphylococcal fibronectin-binding protein (FnBP-A). A specific antibody response against the fibronectin-binding part of the fusion proteins was detected in the serum of all vaccinated animals. The protective potential of these vaccinations was evaluated in a mouse mastitis model, using Staphylococcus aureus, strain SA113, for challenge. The mice vaccinated with FnBP fusion proteins showed a decreased number of bacteria recovered from the mammary glands and significantly reduced cases of severe mastitis. Histopathological examination of tissue from challenged glands of vaccinated mice revealed either no pathological reactions or disseminated inflammatory reactions with focal necrosis whereas four of six examined tissues from challenged glands of non-vaccinated animals showed total necrosis. A combination of FnBP fusion protein with staphylococcal alpha-toxoid did not increase the efficacy of the vaccination and animals vaccinated with alpha-toxoid alone were as sensitive to challenge as those from the non-vaccinated control group. Thus vaccination of mice with recombinant FnBP resulted in significant protection against challenge with S. aureus.