Biomedical subjects

Peter Kraiczy

Publications and source records attributed to Peter Kraiczy.

At least 19 recordsLinked to original sources

PubMed2006

Borrelia burgdorferi complement regulator-acquiring surface protein 1 of the Lyme disease spirochetes is expressed in humans and induces antibody responses restricted to nondenatured structural determinants.

Borrelia burgdorferi complement regulator-acquiring surface protein 1 (CRASP-1), the dominant factor H and FHL-1-binding protein of the Lyme disease spirochete B. burgdorferi, is implicated in pathogen persistence and was recently reported to be nonimmunogenic in humans. Here we show that serum samples from Lyme disease patients contain antibodies with exclusive specificity for nondenatured structural determinants of CRASP-1.

Antibodies, Bacterial↗

PubMed2006

Structure-function mapping of BbCRASP-1, the key complement factor H and FHL-1 binding protein of Borrelia burgdorferi.

Borrelia burgdorferi, a spirochaete transmitted to human hosts during feeding of infected Ixodes ticks, is the causative agent of Lyme disease, the most frequent vector-borne disease in Eurasia and North America. Sporadically Lyme disease develops into a chronic, multisystemic disorder. Serum-resistant B. burgdorferi strains bind complement factor H (FH) and FH-like protein 1 (FHL-1) on the spirochaete surface. This binding is dependent on the expression of proteins termed complement-regulator acquiring surface proteins (CRASPs). The atomic structure of BbCRASP-1, the key FHL-1/FH-binding protein of B. burgdorferi, has recently been determined. Our analysis indicates that its protein topology apparently evolved to provide a high affinity interaction site for FH/FHL-1 and leads to an atomic-level hypothesis for the functioning of BbCRASP-1. This work demonstrates that pathogens interact with complement regulators in ways that are distinct from the mechanisms used by the host and are thus obvious targets for drug design.

Amino Acid Sequence↗

PubMed2006

Risk of culture-confirmed borrelial persistence in patients treated for erythema migrans and possible mechanisms of resistance.

Erythema migrans (EM) develops at the site of the tick bite in 77-90% of Lyme borreliosis (LB) patients and is therefore a common manifestation of early disease. Clinical treatment failures have been reported in early LB cases for almost every suitable antimicrobial agent. The exact risk of resistance to antibiotic treatment in patients with EM, however, is not known and there are few published cases of culture-proven treatment failure. Moreover, currently available diagnostic techniques cannot reliably discriminate between possible reinfection, true endogenous relapse and co-infection with other tick-borne pathogens. These drawbacks together with the phenomenon of resistance to therapy in individual patients undoubtedly contribute to the inconsistencies surrounding the optimal treatment regimens for LB and are often misinterpreted and misused to support prolonged antibiotic treatment regimens. The question for the underlying mechanisms of possible antimicrobial resistance in Borrelia burgdorferi sensu lato remains unresolved but a better understanding of such genetic or phenotypic mechanisms would be helpful for the treatment of LB and other spirochetal diseases. Investigations on this issue, at best, should start with borrelial isolates cultured from patients before the start of antibiotic therapy and again after the conclusion of treatment. This task, however, remains challenging insofar, as culture is rarely successful under routine laboratory conditions after antimicrobial therapy. Here, we review recent clinical and experimental data on treatment resistance in EM patients suggesting that, although rare, borrelial persistence does occur at the site of the infectious lesion after antibiotic treatment. Borrelial persistence, however, is unlikely to result from acquired resistance against antimicrobial agents that were used for initial specific chemotherapy.

Adult↗

PubMed2006

Binding of human complement regulators FHL-1 and factor H to CRASP-1 orthologs of Borrelia burgdorferi.

The complement regulator-acquiring surface protein (CRASP)-1 is a member of the paralogous gene family gbb54 and the dominant FHL-1 and factor H binding protein of Borrelia burgdorferi sensu stricto (s.s.). It was shown recently that expression of BbCRASP-1 directly correlates with serum resistance of B. burgdorferi s.s. isolates. In the present study we have elucidated the putative potential of other members of the gbb54 paralogous family, including orthologs ZSA66, ZSA69, ZSA70, ZSA71, ZSA72 and ZSA73 of the European B. burgdorferi s.s. strain ZS7, to bind human FHL-1 and factor H. In spite of their overall similarity in protein sequence, between 47% and 67%, and the fact that the C-terminal region of ZSA69 shows 70% similarity with BbCRASP-1, none of the orthologous proteins was able to bind human FHL-1 and/or factor H. BbCRASP-1 is the only member of the paralogous gene family gbb54 that binds to human complement regulators, supporting the notion that BbCRASP-1 plays a critical role in evasion of complement by B. burgdorferi s.s. and thus may be helpful in the development of novel therapeutic strategies against Lyme borreliosis.

Bacterial Proteins↗

PubMed2006

Complement escape of human pathogenic bacteria by acquisition of complement regulators.

Pathogenic micro-organisms employ a broad range of strategies to survive in and to persistently infect the human host. Far from being completely understood by which highly sophisticated means invading pathogens overcome the host's destructive immune defence, there is a growing body of evidence on particular mechanisms which play a pivotal role for immune evasion. This review focuses on evasion of medically and scientifically important bacteria by acquisition of host derived fluid-phase complement regulatory proteins, in particular factor H, FHL-1, and C4b binding protein. Expression of microbial surface molecules binding to human complement regulators and thus fixing them in a functionally active state allows pathogens to inhibit and finely regulate complement activation directly on their surface. Further studies on the utilization of host complement regulatory proteins will likely have a marked impact on a more efficient and specific clinical treatment.

Bacteria↗

PubMed2006

Functional characterization of BbCRASP-2, a distinct outer membrane protein of Borrelia burgdorferi that binds host complement regulators factor H and FHL-1.

Borrelia burgdorferi, the aetiological agent of Lyme disease, employs sophisticated means to survive in diverse mammalian hosts. Recent studies demonstrated that acquisition of complement regulators factor H and factor H-like protein-1 (FHL-1) allows spirochetes to resist complement-mediated killing. Serum-resistant B. burgdorferi express up to five distinct complement regulator-acquiring surface proteins (CRASPs) that bind factor H and/or FHL-1. In this study we have identified and characterized one of those B. burgdorferi proteins, named BbCRASP-2. BbCRASP-2 is distinct from the four previously identified factor H/FHL-1-binding CRASPs of B. burgdorferi strains. The single copy of the gene encoding BbCRASP-2, cspZ, is located on the linear plasmid lp28-3. BbCRASP-2 is highly divergent from the factor H/FHL-1-binding protein BbCRASP-1 and from members of the factor H-binding Erp (OspE/F-related) protein family. Peptide mapping analysis revealed that the factor H/FHL-1 binding site is discontinuous and it was found that C-terminal truncations abrogate factor H and FHL-1 binding. The predominant BbCRASP-2 binding site of both host complement regulators was mapped to the short consensus repeat 7 (SCR 7). Factor H and FHL-1 bound to BbCRASP-2 maintain cofactor activity for factor I-mediated C3b inactivation and accelerate the decay of the C3 convertase. Expression of BbCRASP-2 in serum-sensitive B. burgdorferi mutant B313 increased resistance to complement-mediated lysis. The characterization of BbCRASP-2 now provides a complete picture of the three diverse complement regulator-binding protein families of B. burgdorferi yielding new insights into the pathogenesis of Lyme disease.

Amino Acid Sequence↗

PubMed2006

LfhA, a novel factor H-binding protein of Leptospira interrogans.

The early phase of leptospiral infection is characterized by the presence of live organisms in the blood. Pathogenic Leptospira interrogans is resistant to the alternative pathway of complement mediated-killing, while nonpathogenic members of the genus are not. Consistent with that observation, only pathogenic leptospires bound factor H, a host fluid-phase regulator of the alternative complement pathway. Ligand affinity blot analyses revealed that pathogenic L. interrogans produces at least two factor H-binding proteins. Through screening of a lambda phage expression library, we identified one of these as the novel membrane protein LfhA. Ligand affinity assays and surface plasmon resonance analyses of recombinant LfhA revealed specific binding of both factor H and factor H-related protein 1. Serological examination of infected humans and horses demonstrated that LfhA is expressed by L. interrogans during mammalian infection. LfhA may therefore contribute to the resistance of pathogenic leptospires to complement-mediated killing during leptospiremic phases of the disease.

Animals↗

PubMed2005

A novel fold for the factor H-binding protein BbCRASP-1 of Borrelia burgdorferi.

Borrelia burgdorferi, a spirochete transmitted to human hosts during feeding of infected Ixodes ticks, is the causative agent of Lyme disease. Serum-resistant B. burgdorferi strains cause a chronic, multisystemic form of the disease and bind complement factor H (FH) and FH-like protein 1 (FHL-1) on the spirochete surface. Here we report the atomic structure for the key FHL-1- and FH-binding protein BbCRASP-1 and reveal a homodimer that presents a novel target for drug design.

Bacterial Proteins↗

PubMed2005

In vitro susceptibility testing of Borrelia burgdorferi sensu lato isolates cultured from patients with erythema migrans before and after antimicrobial chemotherapy.

Clinical treatment failures have been reported to occur in early Lyme borreliosis (LB) for many suitable antimicrobial agents. Investigations of possible resistance mechanisms of the Borrelia burgdorferi complex must analyze clinical isolates obtained from LB patients, despite their receiving antibiotic treatment. Here, borrelial isolates obtained from five patients with erythema migrans (EM) before the start of antibiotic therapy and again after the conclusion of treatment were investigated. The 10 isolates were characterized by restriction fragment length polymorphism analysis and plasmid profile analysis and subjected to susceptibility testing against a variety of antimicrobial agents including those used for initial chemotherapy. Four out of five patients were infected by the same genospecies (Borrelia afzelii, n = 3; Borrelia garinii, n = 1) at the site of the EM lesion before and after antimicrobial therapy. In one patient the genospecies of the initial isolate (B. afzelii) differed from that of the follow-up isolate (B. garinii). No significant changes in the in vitro susceptibilities became obvious for corresponding clinical isolates before the start and after the conclusion of antimicrobial therapy. This holds true for the antimicrobial agents used for specific chemotherapy of the patients, as well as for any of the additional agents tested in vitro. Our study substantiates borrelial persistence in some EM patients at the site of the infectious lesion despite antibiotic treatment over a reasonable time period. Borrelial persistence, however, was not caused by increasing MICs or minimal borreliacidal concentrations in these isolates. Therefore, resistance mechanisms other than acquired resistance to antimicrobial agents should be considered in patients with LB resistant to treatment.

Adult↗

PubMed2005

Borrelia burgdorferi regulates expression of complement regulator-acquiring surface protein 1 during the mammal-tick infection cycle.

During the natural mammal-tick infection cycle, the Lyme disease spirochete Borrelia burgdorferi comes into contact with components of the alternative complement pathway. B. burgdorferi, like many other human pathogens, has evolved the immune evasion strategy of binding two host-derived fluid-phase regulators of complement, factor H and factor H-like protein 1 (FHL-1). The borrelial complement regulator-acquiring surface protein 1 (CRASP-1) is a surface-exposed lipoprotein that binds both factor H and FHL-1. Analysis of CRASP-1 expression during the mammal-tick infectious cycle indicated that B. burgdorferi expresses this protein during mammalian infection, supporting the hypothesized role for CRASP-1 in immune evasion. However, CRASP-1 synthesis was repressed in bacteria during colonization of vector ticks. Analysis of cultured bacteria indicated that CRASP-1 is differentially expressed in response to changes in pH. Comparisons of CRASP-1 expression patterns with those of other infection-associated B. burgdorferi proteins, including the OspC, OspA, and Erp proteins, indicated that each protein is regulated through a unique mechanism.

Animals↗

PubMed2005

Identification and functional characterization of complement regulator-acquiring surface protein 1 of the Lyme disease spirochetes Borrelia afzelii and Borrelia garinii.

Complement regulator-acquiring surface protein 1 (CRASP-1) is the dominant factor-H-like protein 1 (FHL-1)- and factor-H-binding protein of Borrelia burgdorferi and is suggested to contribute to persistence of the pathogen. The prototype CRASP-1 of B. burgdorferi sensu stricto (CRASP-1Bb) has been formerly characterized. As shown recently, serum-resistant Borrelia afzelii strains express a unique FHL-1 and factor H-binding protein, designated CRASP-1Ba. Here, we describe for the first time the isolation and functional characterization of the gene encoding the full-length CRASP-1Ba of 28 kDa, which, upon processing, is predicted to be 26.4 kDa. CPASP-1Ba of B. afzelii spirochetes is associated with a genetic locus encoding the orthologous gbb54 gene family that maps to the linear plasmid of approximately 54 kb. Ligand affinity blotting techniques demonstrate that both native and recombinant CRASP-1Ba molecules strongly bind to FHL-1 and much more weakly to factor H. The FHL-1 and factor-H-binding site in CRASP-1Ba is shown to be localized to a 12-amino-acid residue domain at the C terminus of the protein. For comparison, the corresponding cspA-like gene(s) of a serum-sensitive Borrelia garinii strain has also been cloned and characterized. Most notably, two CRASP-1-related B. garinii proteins were identified; however, both molecules bind only weakly to FHL-1 and not at all to factor H. The present identification of the binding site of CRASP-1Ba represents an important step forward in our understanding of the pathogenesis of Lyme disease and may be helpful to design therapeutic regimens to interfere with complement evasion strategies of human pathogenic Borrelia strains.

Amino Acid Sequence↗

PubMed2004

Crystallization and preliminary crystallographic analysis of BbCRASP-1, a complement regulator-acquiring surface protein of Borrelia burgdorferi.

Borrelia burgdorferi is the causative agent of Lyme disease. Serum-resistant strains of the pathogen are able to reduce the host's immune response to infection by recruiting fluid-phase complement regulators from the serum. B. burgdorferi complement regulator-acquiring surface protein-1 (BbCRASP-1) binds factor H and factor-H-like protein-1 to the bacterial surface, where they actively down-regulate complement response. Crystals of native and selenomethionine-substituted BbCRASP-1 have been obtained and a native data set to 2.7 A as well as selenomethionine MAD data to 3.2 A resolution have been collected. The selenium substructure has been solved and initial phases have been refined to 3.0 A by density-modification methods. Model building and refinement are under way.

Bacterial Proteins↗

PubMed2004

Immunological characterization of the complement regulator factor H-binding CRASP and Erp proteins of Borrelia burgdorferi.

Complement activation plays an important role in the elimination of invading microorganisms. Borrelia (B.) burgdorferi sensu lato the etiological agent of Lyme borreliosis, can resist complement-mediated killing. The mechanism of complement resistance of B. burgdorferi sensu stricto apparently depends on the expression of several outer surface proteins described as CRASPs (complement regulator-acquiring surface proteins). These borrelial surface proteins are able to bind components of the complement regulatory system, factor H and/or factor H-like protein 1 (FHL-1), two crucial fluid-phase negative regulators of the alternative pathway of complement. It was previously demonstrated that one CRASP is encoded by a member of the erp gene family. The purpose of the study was to use a set of monoclonal antibodies (mAb) and polyclonal antisera to characterize the relatedness of factor H-binding CRASP and Erp proteins among several B. burgdorferi sensu stricto and B. afzelii strains. Based on the observed cross-reactivities between B. burgdorferi sensu stricto strains LW2 and PKa-1, it is concluded that BbCRASP-3 is similar to ErpP, BbCRASP-4 is structurally related to ErpC, and BbCRASP-5 is similar to ErpA. The BaCRASP-2 and BaCRASP-4 proteins of B. afzelii strain EB1 reacted with both anti-ErpA and anti-ErpP antibodies whereas BaCRASP-5 of B. afzelii strain FEM1-D15 exclusively reacted with BbCRASP-3/ErpP specific antibodies. Together, these data indicate that most of the factor H-binding CRASPs are members of the Erp protein family, which represents a polymorphic class of proteins with similar or identical immunological reactivities.

Antigens, Bacterial↗

PubMed2004

Comparison of in vitro activities of ketolides, macrolides, and an azalide against the spirochete Borrelia burgdorferi.

Two ketolides, three macrolides, and one azalide were tested in vitro against 17 isolates of the B. burgdorferi s.l. complex. As measured in micrograms per milliliter, activity was highest for cethromycin (MIC at which 90% of the tested isolates were inhibited [MIC(90)], 0.0019 micro g/ml) and telithromycin (MIC(90), 0.0078 micro g/ml). Electron-microscope analysis and time-kill studies also supported enhanced effectiveness of both ketolides.

Anti-Bacterial Agents↗

PubMed2003

Complement resistance of Borrelia burgdorferi correlates with the expression of BbCRASP-1, a novel linear plasmid-encoded surface protein that interacts with human factor H and FHL-1 and is unrelated to Erp proteins.

The etiologic agent of Lyme disease, Borrelia burgdorferi, is capable of circumventing the immune defense of a variety of potential vertebrate hosts. Previous work has shown that interaction of host-derived complement regulators, factor H and factor H-like protein 1 (FHL-1), with up to five complement regulator-acquiring surface proteins (CRASPs) expressed by resistant B. burgdorferi sensu lato isolates conferred complement resistance. In addition expression of CRASP-1 is directly correlated with complement resistance of Borrelia species. This work describes the functional characterization of BbCRASP-1 as the dominant factor H and FHL-1-binding protein of B. burgdorferi. The corresponding gene, zs7.a68, is located on the linear plasmid lp54 and is different from factor H-binding Erp proteins that are encoded by genes localized on circular plasmids (cp32). Deletion mutants of BbCRASP-1 were generated, and a high affinity binding site for factor H and FHL-1 was mapped to the C terminus of BbCRASP-1. Similarly, the predominant binding site of factor H and FHL-1 was localized to the short consensus repeat 7. Factor H and FHL-1 maintain their cofactor activity for factor I-mediated C3b inactivation when bound to BbCRASP-1, and factor H is up to 6-fold more efficient in mediating C3b conversion than FHL-1. In conclusion, BbCRASP-1 (i). binds the host complement regulators factor H and FHL-1 with high affinity, (ii). is the key molecule of the complement resistance of spirochetes, and (iii). is distinct from the Erp protein family. Thus, BbCRASP-1 most likely contributes to persistence of B. burgdorferi and to pathogenesis of Lyme disease.

Amino Acid Sequence↗

PubMed2003

Immune evasion of Borrelia burgdorferi: mapping of a complement-inhibitor factor H-binding site of BbCRASP-3, a novel member of the Erp protein family.

The causative agents of Lyme disease, Borrelia burgdorferi s.s., B. garinii, and B. afzelii, differ in their susceptibility to complement-mediated lysis. This phenomenon apparently depends on the expression of proteins termed complement regulator-acquiring surface proteins (CRASP) and their binding to the inhibitory plasma proteins factor H and FHL-1. To characterize these bacterial proteins in more detail we have now isolated from a B. burgdorferi expression library a novel factor H-binding protein. In accordance with our previous studies this protein was termed BbCRASP-3 and represents a novel member of the polymorphic Erp (OspE/F-related) protein family. On the basis of protease accessibility assays using intact spirochetes, BbCRASP-3 is identified as a surface-exposed protein and binds the C-terminal short consensus repeats of factor H. Applying deletion mutants of BbCRASP-3, the factor H-binding site was mapped to the nine-amino-acid motif LEVLKKNLK localized at the C-terminal end of BbCRASP-3. Factor H bound to BbCRASP-3 maintains its cofactor activity in factor I-mediated C3b inactivation. Binding of BbCRASP-3 to factor H can be inhibited by heparin, a physiological ligand of the complement regulator factor H. Blocking of factor-H-binding by soluble BbCRASP-3 leads to an increase of complement deposition on intermediate serum-resistant strain ZS7. In conclusion, BbCRASP-3 has been identified as a novel factor H-binding protein on B. burgdorferi which by conferring complement resistance to the pathogen may contribute to its persistence in the mammalian host.

Amino Acid Sequence↗

PubMed2002

The responsiveness of human V delta 1 gamma delta T cells to Borrelia burgdorferi is largely restricted to synovial-fluid cells from patients with Lyme arthritis.

It has been shown that human gamma delta T cells expressing the V delta 1 T cell receptor (TCR) respond to the spirochete Borrelia burgdorferi. Lysates of 3 Borrelia genospecies triggered the proliferation of peripheral-blood mononuclear cells not only from patients with skin manifestations of Borrelia infection and from patients with Lyme arthritis but also from healthy donors. However, with the exception of 1 patient with Lyme arthritis, no selective expansion of V delta 1-expressing gamma delta T cells was induced. In contrast, synovial-fluid mononuclear cells (SFMC) from 3 of 5 patients with Lyme arthritis responded with a selective outgrowth of V delta 1 gamma delta T cells. V delta 1 gamma delta T cell lines established from SFMC coexpressed various TCR V gamma chains, although V gamma 8 was preferentially used. Thus, the responsiveness to Borrelia antigens is not a general property of V delta 1-expressing gamma delta T cells but is largely restricted to V delta 1 gamma delta T cells recruited into the inflamed tissue.

Adolescent↗

PubMed2002

Complement regulator-acquiring surface proteins of Borrelia burgdorferi: a new protein family involved in complement resistance.

The innate immune system, particularly the host complement system, plays an important role in the elimination of invading pathogens. Borrelia burgdorferi, like other human pathogens, has developed strategies to prevent complement-mediated bacteriolysis. It is now well established that Borrelia differ in their complement resistance. In general terms, B. afzelii isolates are mainly resistant to complement-mediated bacteriolysis, whereas the majority of B. burgdorferi s.s. isolates display an intermediate complement-resistant phenotype. Most of the B. garinii isolates, in contrast, are efficiently killed by complement and, therefore, are classified as complement-sensitive. Complement resistance of B. afzelii and B. burgdorferi s.s. isolates correlates directly with the acquisition of the fluid-phase human complement regulators FHL-1/reconectin and factor H. To date, five distinct complement regulator-acquiring surface proteins (CRASPs) have been identified in B. afzelii and B. burgdorferi s.s. isolates. The individual CRASPs can be differentiated according to their size and their binding properties to FHL-1/reconectin and factor H. The domains that interact with CRASPs are localized at the C-terminal ends of these complement regulators. Thus, CRASPs represent a family of functional proteins involved in complement resistance of Borrelia. Furthermore, an alterable pattern of gene expression was observed for three CRASPs of B. afzelii: BaCRASP-1, BaCRASP-2, and BaCRASP-5 are up-regulated at 37 degrees C and down-regulated at 20 degrees C. The continued characterization of CRASPs at the molecular level is expected to identify new virulence factors and potential vaccine candidates.

Animals↗