1.
Sadziene, Ariadna, et al.
(författare)
A bactericidal antibody to Borrelia burgdorferi is directed against a variable region of the OspB protein
1994
Ingår i: Infection and Immunity. - : American Society for Microbiology (ASM). - 0019-9567 .- 1098-5522. ; 62:5, s. 2037-2045
Tidskriftsartikel (refereegranskat) abstract
Borrelia burgdorferi, an agent of Lyme disease, is killed by some monoclonal antibodies in the absence of complement or phagocytes. In the present study, the bactericidal action of monoclonal antibodies against B. burgdorferi and B. hermsii, a cause of relapsing fever, was further characterized. H6831, an antibody recognizing the OspB proteins of some B. burgdorferi strains, and H4825, an antibody specific for one serotype of B. hermsii, were purified, and Fab fragments of the antibodies were prepared. In time-kill studies, more than 99.9% of strain B31 B. burgdorferi cells were killed after 30 min of exposure to H6831 Fab fragments. The MBC of the Fab fragments was 10 micrograms/ml. Electron microscopy revealed that the bactericidal Fab fragments produced numerous blebs and cell lysis of the borrelias for which they were specific. To identify the epitope for H6831, the OspB sequences of H6831-susceptible and -resistant strains and mutants were determined. The deduced OspB proteins of all H6831-resistant strains and mutants differed from the strain B31 OspB at residue 253. Murine antisera raised against a 21-mer synthetic peptide representing the region around residue 253 were specific for strain B31 by Western blot (immunoblot) and growth inhibition assays. Furthermore, the antipeptide serum inhibited the binding of H6831 to whole borrelias. These findings indicated that the linear component of the bactericidal antibody's epitope was located at or near residue 253.
2.
Nunez-Otero, Carlos, 1992-
(författare)
Novel inhibitors of Chlamydia trachomatis virulence
2020
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Chlamydia trachomatis is an obligate intracellular bacterium that infects over 100 million people globally every year. Chlamydia infections can be persistent, cause infertility and blindness, adding an economical burden in the healthcare systems. Moreover, Chlamydia infections are treated with broad-spectrum antibiotics that contribute to the selection of antibiotic resistant bacteria in the commensal flora. For this reason, novel compounds with specificity against C. trachomatis would be important for treatment of Chlamydia infections.We have developed a new class of substituted 2-pyridone amides that inhibited development of C. trachomatis. While bacterial growth was only affected to a limited extent, the produced progeny bacteria had impaired capacity to infect new cells. The compounds presented no toxicity in human or mouse cell lines and they did not inhibit growth of bacteria from the normal flora. Structure activity relationship (SAR) development of 2-pyridones lead to compounds with effect at nanomolar concentrations. Further modifications of the C3 part of the molecules resulted in isostere compounds with even a higher potency. By exploring the C8 position, we observed that methylsulfonamide substituents improved the pharmacokinetic properties and enabled oral uptake in mice. This discovery opens the door for oral treatment.Among 2-pyridone amides, KSK213 was one of the most potent and we investigated the mode of action on the life cycle of C. trachomatis. KSK213 reduced transcription by the end of the developmental cycle and upon infection of new host cells. Mutations in RNA helicase and RNAse III genes, involved in transcription, mediated resistance to KSK213. It also attenuated the infectivity in a mouse vaginal infection model. To further explore the molecular target for 2-pyridone amides in Chlamydia, we used a custom synthesized probe for affinity chromatography approaches.Here we show that 2-pyridones are potent non-toxic inhibitors of C. trachomatis that can be chemically modified to increase potency and enable oral bioavailability. These molecules have the potential to treat and prevent Chlamydia infections without affecting the normal flora.
3.
Berthold, Anne, et al.
(författare)
Cultivation Methods of Spirochetes from Borrelia burgdorferi Sensu Lato Complex and Relapsing Fever Borrelia
2022
Ingår i: Journal of Visualized Experiments. - : MyJove Corporation. - 1940-087X. ; 2022:189
Tidskriftsartikel (refereegranskat) abstract
The Borrelia consists of three groups of species, those of the Lyme borreliosis (LB) group, also known as B. burgdorferi sensu lato (s.l.) and recently reclassified into Borreliella, the relapsing fever (RF) group Borrelia, and a third reptile-associated group of spirochetes. Culture-based methods remain the gold standard for the laboratory detection of bacterial infections for both research and clinical work, as the culture of pathogens from bodily fluids or tissues directly detects replicating pathogens and provides source material for research. Borrelia and Borreliella spirochetes are fastidious and slow growing, and thus are not commonly cultured for clinical purposes; however, culture is necessary for research. This protocol demonstrates the methodology and recipes required to successfully culture LB and RF spirochetes, including all recognized species from B. burgdorferi s.l. complex including B. afzelii, B. americana, B. andersonii, B. bavariensis, B. bissettii/bissettiae, B. burgdorferi sensu stricto (s.s.), B. californiensis, B. carolinensis, B. chilensis, B. finlandensis, B. garinii, B. japonica, B. kurtenbachii, B. lanei, B. lusitaniae, B. maritima, B. mayonii, B. spielmanii, B. tanukii, B. turdi, B. sinica, B. valaisiana, B. yangtzensis, and RFspirochetes, B. anserina, B. coriaceae, B. crocidurae, B. duttonii, B. hermsii, B. hispanica, B. persica, B. recurrentis, and B. miyamotoi. The basic medium for growing LB and RF spirochetes is the Barbour-Stoenner-Kelly (BSK-II or BSK-H) medium, which reliably supports the growth of spirochetes in established cultures. To be able to grow newly isolated Borrelia isolates from tick-or host-derived samples where the initial spirochete number is low in the inoculum, modified Kelly-Pettenkofer (MKP) medium is preferred. This medium also supports the growth of B. miyamotoi. The success of the cultivation of RF spirochetes also depends critically on the quality of ingredients.
4.
Curtis, Michael W., et al.
(författare)
Identification of amino acid domains of Borrelia burgdorferi P66 that are surface exposed and important for localization, oligomerization, and porin function of the protein
2022
Ingår i: Frontiers in Cellular and Infection Microbiology. - : Frontiers Media S.A.. - 2235-2988. ; 12
Tidskriftsartikel (refereegranskat) abstract
P66, a bifunctional integral outer membrane protein, is necessary for Borrelia burgdorferi to establish initial infection and to disseminate in mice. The integrin binding function of P66 facilitates extravasation and dissemination, but the role of its porin function during murine infection has not been investigated. A limitation to studying P66 porin function during mammalian infection has been the lack of structural information for P66. In this study, we experimentally characterized specific domains of P66 with regard to structure and function. First, we aligned the amino acid sequences of P66 from Lyme disease-causing Borrelia and relapsing fever-causing Borrelia to identify conserved and unique domains between these disease-causing clades. Then, we examined whether specific domains of P66 are exposed on the surface of the bacteria by introducing c-Myc epitope tags into each domain of interest. The c-Myc epitope tag inserted C-terminally to E33 (highly conserved domain), to T187 (integrin binding region domain and a non-conserved domain), and to E334 (non-conserved domain) were all detected on the surface of Borrelia burgdorferi. The c-Myc epitope tag inserted C-terminally to E33 and D303 in conserved domains disrupted P66 oligomerization and porin function. In a murine model of infection, the E33 and D303 mutants exhibited decreased infectivity and dissemination. Taken together, these results suggest the importance of these conserved domains, and potentially P66 porin function, in vivo.
5.
Normark, Johan, et al.
(författare)
Maladjusted Host Immune Responses Induce Experimental Cerebral Malaria-Like Pathology in a Murine Borrelia and Plasmodium Co-Infection Model
2014
Ingår i: PLOS ONE. - : PLOS ONE. - 1932-6203. ; 9:7
Tidskriftsartikel (refereegranskat) abstract
In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1 beta and TNF-alpha, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells.
6.
Sandholm, Kerstin, et al.
(författare)
Early Cytokine Release in Response to Live Borrelia burgdorferi Sensu Lato Spirochetes Is Largely Complement Independent
2014
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9, s. e108013-
Tidskriftsartikel (refereegranskat) abstract
Aim: Here we investigated the role of complement activation in phagocytosis and the release of cytokines and chemokines in response to two clinical isolates: Borrelia afzelii K78, which is resistant to complement-mediated lysis, and Borrelia garinii LU59, which is complement-sensitive. Methods: Borrelia spirochetes were incubated in hirudin plasma, or hirudin-anticoagulated whole blood. Complement activation was measured as the generation of C3a and sC5b-9. Binding of the complement components C3, factor H, C4, and C4BP to the bacterial surfaces was analyzed. The importance of complement activation on phagocytosis, and on the release of cytokines and chemokines, was investigated using inhibitors acting at different levels of the complement cascade. Results: 1) Borrelia garinii LU59 induced significantly higher complement activation than did Borrelia afzelii K78. 2) Borrelia afzelii K78 recruited higher amounts of factor H resulting in significantly lower C3 binding. 3) Both Borrelia strains were efficiently phagocytized by granulocytes and monocytes, with substantial inhibition by complement blockade at the levels of C3 and C5. 4) The release of the pro-inflammatory cytokines and chemokines IL-1 beta, IL-6, TNF, CCL20, and CXCL8, together with the anti-inflammatory IL-10, were increased the most (by>10-fold after exposure to Borrelia). 5) Both strains induced a similar release of cytokines and chemokines, which in contrast to the phagocytosis, was almost totally unaffected by complement blockade. Conclusions: Our results show that complement activation plays an important role in the process of phagocytosis but not in the subsequent cytokine release in response to live Borrelia spirochetes.
7.
Shoberg, Russel J., et al.
(författare)
Identification of a highly cross-reactive outer surface protein B epitope among diverse geographic isolates of Borrelia spp. causing Lyme disease
1994
Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology (ASM). - 0095-1137 .- 1098-660X. ; 32:2, s. 489-500
Tidskriftsartikel (refereegranskat) abstract
The outer surface lipoprotein B (OspB) of Borrelia burgdorferi is a major component of the borrelial protein profile and has been shown to be highly immunogenic in experimentally immunized and infected mammals. However, the ospB loci of different strains show considerable heterology at the nucleic acid sequence level, and the progeny of a clonal strain of B. burgdorferi exhibited OspB polymorphisms with respect to apparent molecular weights and reactivities with monoclonal antibodies. These data suggest that OspB is not a good candidate for vaccination or diagnostic purposes. The present study describes a monoclonal antibody, designated 84C, directed against a very highly conserved domain of the OspB lipoprotein. Western immunoblot analysis with 84C demonstrated reactivity in 84.2% of human, tick, and other vertebrate isolate strains examined from widely diverse geographic regions, including strains of B. burgdorferi sensu stricto and two closely related species, B. garinii and B. afzelii. The 84C-binding region was delimited to a highly conserved 11-amino-acid region in the carboxyl terminus of OspB as demonstrated by (i) DNA sequence analysis of wild-type and 84C-resistant mutant ospB alleles and (ii) deletion mutagenesis of a recombinant ospB gene in Escherichia coli. Finally, the 84C epitope was demonstrated to be exposed on the borrelial surface in situ as (i) the monoclonal antibody 84C was able to agglutinate borrelias in culture and (ii) 84C-resistant escape variants were isolated. These data suggest that the potential value of OspB as a vaccine candidate or diagnostic tool be examined more closely, in the context of the 84C-reactive domain.
8.
Bailey, Leslie, et al.
(författare)
Small molecule inhibitors of type III secretion in Yersinia block the Chlamydia pneumoniae infection cycle
2007
Ingår i: FEBS Letters. - : Elsevier. - 0014-5793 .- 1873-3468. ; 581:4, s. 587-595
Tidskriftsartikel (refereegranskat) abstract
Intracellular parasitism by Chlamydiales is a complex process involving transmission of metabolically inactive particles that differentiate, replicate, and re-differentiate within the host cell. A type three secretion system (T3SS) has been implicated in this process. We have here identified small molecules of a chemical class of acylated hydrazones of salicylaldehydes that specifically blocks the T3SS of Chlamydia. These compounds also affect the developmental cycle showing that the T3SS has a pivotal role in the pathogenesis of Chlamydia. Our results suggest a previously unexplored avenue for development of novel anti-chlamydial drugs.
9.
Bárcena-Uribarri, Iván, et al.
(författare)
P66 porins are present in both Lyme disease and relapsing fever spirochetes : a comparison of the biophysical properties of P66 porins from six Borrelia species
2010
Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier. - 0005-2736 .- 1879-2642. ; 1798:6, s. 1197-1203
Tidskriftsartikel (refereegranskat) abstract
The genus Borrelia is the cause of the two human diseases: Lyme disease (LD) and relapsing fever (RF). BothLD and RF Borrelia species are obligate parasites and are dependent on nutrients provided by their hosts. Thefirst step of nutrient uptake across the outer membrane of these Gram-negative bacteria is accomplished bywater-filled channels, so-called porins. The knowledge of the porin composition in the outer membranes ofthe different pathogenic Borrelia species is limited. Only one porin has been described in relapsing feverspirochetes to date, whereas four porins are known to be present in Lyme disease agents. From these, theBorrelia burgdorferi outer membrane channel P66 is known to act as an adhesin and was well studied as aporin. To investigate if P66 porins are expressed and similarly capable of pore formation in other Borreliacausing Lyme disease or relapsing fever three LD species (B. burgdorferi, B. afzelii, B. garinii) and three RFspecies (B. duttonii, B. recurrentis and B. hermsii) were investigated for outer membrane proteins homologousto P66. A search in current published RF genomes, comprising the ones of B. duttonii, B. recurrentis and B.hermsii, indicated that they all contained P66 homologues. The P66 homologues of the six Borrelia specieswere purified to homogeneity and their pore-forming abilities as well as the biophysical properties of thepores were analyzed using the black lipid bilayer assay.
10.
Barcena-Uribarri, Ivan, et al.
(författare)
Use of Nonelectrolytes Reveals the Channel Size and Oligomeric Constitution of the Borrelia burgdorferi P66 Porin
2013
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:11, s. e78272-
Tidskriftsartikel (refereegranskat) abstract
In the Lyme disease spirochete Borrelia burgdorferi, the outer membrane protein P66 is capable of pore formation with an atypical high single-channel conductance of 11 nS in 1 M KCl, which suggested that it could have a larger diameter than 'normal' Gram-negative bacterial porins. We studied the diameter of the P66 channel by analyzing its single-channel conductance in black lipid bilayers in the presence of different nonelectrolytes with known hydrodynamic radii. We calculated the filling of the channel with these nonelectrolytes and the results suggested that nonelectrolytes (NEs) with hydrodynamic radii of 0.34 nm or smaller pass through the pore, whereas neutral molecules with greater radii only partially filled the channel or were not able to enter it at all. The diameter of the entrance of the P66 channel was determined to be <= 1.9 nm and the channel has a central constriction of about 0.8 nm. The size of the channel appeared to be symmetrical as judged from one-sidedness of addition of NEs. Furthermore, the P66-induced membrane conductance could be blocked by 80-90% by the addition of the nonelectrolytes PEG 400, PEG 600 and maltohexaose to the aqueous phase in the low millimolar range. The analysis of the power density spectra of ion current through P66 after blockage with these NEs revealed no chemical reaction responsible for channel block. Interestingly, the blockage of the single-channel conductance of P66 by these NEs occurred in about eight subconductance states, indicating that the P66 channel could be an oligomer of about eight individual channels. The organization of P66 as a possible octamer was confirmed by Blue Native PAGE and immunoblot analysis, which both demonstrated that P66 forms a complex with a mass of approximately 460 kDa. Two dimension SDS PAGE revealed that P66 is the only polypeptide in the complex.
