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S B Svenson

Publications and source records attributed to S B Svenson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Synthesis and immunologic characterisation of Mycobacterium tuberculosis lipoarabinomannan specific oligosaccharide-protein conjugates.

Lipoarabinomannan (LAM) is a major structural surface component of all mycobacteria, and has been reported to have a wide range of biological effects. Immunogenic LAM specific oligosaccharide protein conjugates were synthesized and immunologically characterized. Oligosaccharides were derived from LAM purified from Mycobacterium tuberculosis H37 Rv and covalently conjugated to tetanus toxoid and cross reactive mutant (CRM197) diphtheria toxoid. Both types of LAM oligosaccharide protein conjugates proved to be highly immunogenic, inducing a boosterable T helper cell dependent IgG response. These conjugates are currently evaluated as components in a subcellular experimental TB vaccine.

Animals↗
PubMed1999

Electron beam fragmentation of bacterial polysaccharides as a method of producing oligosaccharides for the preparation of conjugate vaccines.

End-group mediated conjugation of bacterial polysaccharides (PSs) to carrier proteins containing T-helper cell epitopes renders such polysaccharides immunogenic also in young infants. Optimal construction of such conjugate vaccines requires fragmentation of the PS prior to the coupling reaction. In the present study a general simple and inexpensive method for the fragmentation of PSs is presented. It is based on the irradiation of isolated PSs in an electron beam accelerator. Exposure of isolated pneumococcal capsular polysaccharides (PnPSs) to ionizing radiation resulted in their partial depolymerization in a radiation dose-dependent manner. Radiation, unlike sonication, generated PnPS fragments of molecular size lower than 50 kDa and as small as 1.5 kDa when high radiation doses were used. These PnPS fragments have terminal reducing groups that can be easily used for chemical activation and subsequent coupling to any chosen carrier protein. The radiation-produced PnPS fragments retained their antigenic epitopes, when compared to native, full-size PnPSs as determined by enzyme-linked immunoassay.

Animals↗
PubMed1999

Nasal and parenteral immunizations with diphtheria toxoid using monoglyceride/fatty acid lipid suspensions as adjuvants.

A novel suspension system was developed where monoglycerides were formulated together with fatty acids and subsequently admixed with antigens. In the present study, diphtheria toxoid was used as a model antigen primarily due to its weak immunological properties as well as to its importance as a future human vaccine for mucosal, particularly nasal immunization. The formulations were administered parenterally and/or nasally to mice whereafter the immune response was determined. In the present study, we have shown that mono-olein/oleic acid vesicles enhance the immunogenicity of admixed diphtheria toxoid in mice to the same level as Alum adsorbed (or Freund's complete adjuvant) when administered parenterally or nasally. It was also shown that the immunogenicity was linked to the length of the acyl chain of the lipids, where shorter acyl chains resulted in reduced titers. Furthermore, shorter acyl chains also gave rise to more pronounced toxic reactions at the injections sites, such as necrosis and alopeci, both of which were lacking when the optimal formulation consisting of mono-olein and oleic acid was used. Thus, this lipid matrix has in our view a great potential as an immunological adjuvant with an exceptionally simple and efficient preparation procedure without organic solvents and with low cost endogenous lipid based raw materials.

Adjuvants, Immunologic↗
PubMed1999

A new method of non-cross-linking conjugation of polysaccharides to proteins via thioether bonds for the preparation of saccharide-protein conjugate vaccines.

Bacterial polysaccharides, including capsular polysaccharides, are poor immunogens particularly in young infants. However, conjugation of bacterial polysaccharides to immunogenic carrier proteins generally results in conjugates that induce strong antipolysaccharide T-helper-cell dependent immune responses, also in young infants. The magnitude of the response and the extent of the T-helper-cell dependency is related to the chemical characteristics of the particular conjugate such as presence or absence of polysaccharide-protein cross-linking, presence or absence of spacer arms, character of spacer arms, type of carrier protein, size of conjugated polysaccharide hapten and molar degree of substitution. In the present study a new, general and simple method for the preparation of poly- and oligosaccharide-protein conjugates is presented. This new method is based on spacer-introducing chemistry that allowed for conjugation of a model polysaccharide, dextran, ranging in size from 0.5 to 150 kDa, to tetanus toxoid (TTd). The developed conjugation method involves derivatization of polysaccharide with 2-iminothiolane (2-IT) and activation of carrier protein, such as TTd, with N-hydroxysuccinimide ester of bromoacetic acid. Reaction rates and accordingly the substitution of the conjugates, could be controlled by varying time, pH and concentration of the reactants. Unlike direct reductive amination, the 2-IT based conjugation technology is fast and made it possible to couple fairly large polysaccharides to TTd.

Dextrans↗
PubMed1999

A new rapid and simple method for large-scale purification of mycobacterial lipoarabinomannan.

Lipoarabinomannan (LAM) is a major and structurally important outer cell wall component of all mycobacteria. LAM is also generally regarded as an important immunomodulating substance affecting several immunologic networks and hence important in the pathogenesis of mycobacterial infections. We here describe a new method for large-scale purification of mycobacterial LAM. A crude cell wall preparation was prepared from batch-grown Mycobacterium tuberculosis H37Rv. From this cell wall preparation LAM was purified by sequential extractions and chromatographic steps. From 20 g dry weight cell wall preparation 313 mg of highly purified (> 98%) LAM was obtained in only 3 days. The LAM content of the final purification step was quantified by ELISA using reference LAM as standard. The identity and purity of the LAM preparation was further confirmed by comparison with reference LAM preparation from M. tuberculosis strain Erdman in polyacrylamide gel electrophoresis and Western blots, using reference anti-LAM monoclonals CS-35 and CS-40.

Antigens, Bacterial↗
PubMed1999

In vitro expansion of T-cell-receptor Valpha2.3(+) CD4(+) T lymphocytes in HLA-DR17(3), DQ2(+) individuals upon stimulation with Mycobacterium tuberculosis.

The T-cell receptor (TCR) Valpha/beta gene product expression upon in vitro stimulation with mycobacteria was investigated to assess whether T-cell proliferation was associated with any specific TCR V gene usage. T-cell-enriched populations from peripheral blood of Mycobacterium bovis BCG-vaccinated healthy blood donors were stimulated in vitro with live or killed M. tuberculosis or with a soluble extract thereof. TCR Valpha/beta repertoire analysis of reactive CD4(+) and CD8(+) T cells revealed a selective HLA-DR17(3), DQ2-restricted expansion of Valpha2.3(+) CD4(+) T cells upon stimulation with live M. tuberculosis or its soluble extract. Third-complementarity-determining-region (CDR3) length analysis of the expanded Valpha2.3(+) T cells indicated an oligoclonal pattern with short CDR3 lengths in six of seven HLA-DR17(3), DQ2(+) individuals tested. In addition, Valpha/Vbeta repertoire analysis of T lymphocytes from a DR17(3), DQ2(+) donor before and after BCG vaccination revealed that positivity of skin test reactivity was associated with expansion of Valpha2.3(+) CD4(+) T lymphocytes with preferential use of a short CDR3 peak length after in vitro stimulation. Separation of M. tuberculosis soluble extract by fast protein liquid chromatography (FPLC) purification indicated that fractions corresponding to molecular masses of 60 to 70 and 15 to 25 kDa were particularly effective in eliciting Valpha2.3(+) CD4(+) T-cell expansion.

BCG Vaccine↗
PubMed1999

Evolution and clonal traits of Mycobacterium tuberculosis complex in Guinea-Bissau.

Two hundred twenty-nine consecutive isolates of Mycobacterium tuberculosis complex from patients with pulmonary tuberculosis in Guinea-Bissau, which is located in West Africa, were analyzed for clonal origin by biochemical typing and DNA fingerprinting. By using four biochemical tests (resistance to thiophene-2-carboxylic acid hydrazide, niacin production, nitrate reductase test, and pyrazinamidase test), the isolates could be assigned to five different biovars. The characteristics of four strains conformed fully with the biochemical criteria for M. bovis, while those of 85 isolates agreed with the biochemical criteria for M. tuberculosis. The remaining 140 isolates could be allocated into one of three biovars (biovars 2 to 4) representing a spectrum between the classical bovine (biovar 1) and human (biovar 5) tubercle bacilli. By using two genotyping methods, restriction fragment length polymorphism analysis with IS6110 (IS6110 RFLP analysis) and spoligotyping, the isolates could be separated into three groups (groups A to C) of the M. tuberculosis complex. Group A (n = 95), which contained the majority of classical human M. tuberculosis isolates, had large numbers of copies of IS6110 elements (mean number of copies, 9) and a distinctive spoligotyping pattern that lacked spacers 33 to 36. Isolates of the major group, group B (n = 119), had fewer IS6110 copies (mean copy number, 5) and a spoligotyping pattern that lacked spacers 7 to 9 and 39 and mainly comprised isolates of biovars 1 to 4. Group C isolates (n = 15) had one to three IS6110 copies, had a spoligotyping pattern that lacked spacers 29 to 34, and represented biovar 3 to 5 isolates. Four isolates whose biochemical characteristics conformed with those of M. bovis clustered with the group B isolates and had spoligotype patterns that differed from those previously reported for M. bovis, in that they possessed spacers 40 to 43. Interestingly, isolates of group B and, to a certain extent, also isolates of group C showed a high degree of variability in biochemical traits, despite genotypic identity in terms of IS6110 RFLP and spoligotype patterns. We hypothesize that isolates of groups B and C have their evolutionary origin in West Africa, while group A isolates are of European descent.

Adult↗
PubMed1998

Aeromonas hydrophila septicaemia in a grey seal (Halichoerus grypus) from the Baltic Sea: a case study.

Aeromonas hydrophila septicaemia in a grey seal (Halichoerus grypus) from the Swedish part of the Baltic Sea is reported. The pathogen was isolated from both lung and spleen specimens. All of the A. hydrophila isolates produced haemolysin and Vero active cytotoxin. The aerolysin gene was found in all tested isolates as evidenced by the polymerase chain reaction (PCR) technique. Also, all isolates tested showed identical patterns of biochemical and antibiotic resistance. As Aeromonas spp. commonly occur in aquatic environments, we suggest that organisms from this genus may also play an important role as opportunistic pathogens in morbillivirus infected seals.

Aeromonas hydrophila↗
PubMed1998

Gammadelta+ and CD4+ alphabeta+ human T cell subset responses upon stimulation with various Mycobacterium tuberculosis soluble extracts.

By using a flow cytometric technique which allows direct identification of proliferating cells within mixed cell populations, we have previously described that soluble extracts obtained from Mycobacterium tuberculosis or M. avium represent strong stimuli for human gammadelta+ T cells. In the present study, we demonstrate that the protocol used for the preparation of M. tuberculosis soluble extracts may have an impact on their gammadelta+ T cell stimulatory capacity. In agreement with our previous data, soluble extracts prepared from bacteria killed at 85 degrees C and directly disrupted by prolonged sonication (TBe), elicited a strong proliferation of gammadelta+ T cells after 6-7 days of stimulation. In contrast, when soluble extracts were obtained from bacteria autoclaved (121 degrees C, 25 min) and then washed by centrifugation, a predominant proportion of CD4+ alphabeta+ T cells was achieved in the responding population. The stimulatory activity for gammadelta+ T cells was recovered in the supernatant of the autoclaved bacteria, indicating that autoclaving of M. tuberculosis bacilli releases an antigen(s) into the supernatant which stimulates human gammadelta+ T cells. While protease digestion of TBe only partially reduced its stimulatory capacity on gammadelta+ T cells, the stimulatory component(s) released into the supernatant after autoclavation of bacilli was found to be sensitive to protease digestion. Interestingly, in contrast to the preponderant proportion of gammadelta+ T cells induced in the responding population by unfractionated TBe, when the extract was fractionated by fast performance liquid chromatography (FPLC), most of the fractions exhibited a strong stimulatory capacity on CD4+ alphabeta+ T cells only. The gammadelta+ T cell stimulatory activity was confined to the low molecular weight range FPLC fractions. Such results may suggest a possible regulatory role of gammadelta+ T cells on CD4+ alphabeta+ T cells.

Antigen Presentation↗
PubMed1998

Involvement of antilipoarabinomannan antibodies in classical complement activation in tuberculosis.

We examined alternative and classical complement activation induced by whole bacilli of Mycobacterium bovis BCG and Mycobacterium tuberculosis products. After exposure to BCG, there were higher levels of the terminal complement complex in sera from Indian tuberculosis patients than in sera from healthy controls. The addition of BCG with or without EGTA to these sera indicated that approximately 70 to 85% of the total levels of the terminal complement complex was formed by classical activation. Sera from Indian tuberculosis patients contained more antibody to lipoarabinomannan (LAM) than sera from healthy Indians. Levels of anti-LAM immunoglobulin G2 (IgG2), but not anti-LAM IgM, correlated positively with classical activation induced by BCG in the sera. By flow cytometry, deposition of C3 and terminal complement complex on bacilli incubated with normal human serum was demonstrated. The anticomplement staining was significantly reduced in the presence of EGTA and EDTA. Flow cytometry also revealed the binding of complement to BCG incubated with rabbit anti-LAM and then with factor B-depleted serum. This indicates that classical activation plays a major role in complement activation induced by mycobacteria and that anti-LAM IgG on the bacilli can mediate this response. Classical complement activation may be important for the extent of phagocytosis of M. tuberculosis by mononuclear phagocytes, which may influence the course after infection.

Adolescent↗
PubMed1998

Drug resistant tuberculosis in Estonia.

SETTING: The incidence of drug resistant tuberculosis in Estonia has increased rapidly during the last five to six years. OBJECTIVE: To investigate the drug resistance patterns of Mycobacterium tuberculosis isolated from tuberculosis patients in Estonia. RESULTS: In 1994, 623 cases of tuberculosis were diagnosed in Estonia, 518 new cases with no previous history of tuberculosis, and 105 with a history of previous treatment for tuberculosis. All pulmonary M. tuberculosis isolates from 1994 were analysed for drug susceptibility. Of the 302 new cases (58.3%) that were culture verified, 28% had isolates resistant to one or more of the four drugs tested (isoniazid, rifampicin, streptomycin, ethambutol), and 9% had multi-drug resistant (resistant to at least isoniazid and rifampicin) strains. CONCLUSION: The incidence of drug resistance in M. tuberculosis is high in Estonia.

Adult↗
PubMed1996

Pulmonary tuberculosis in Guinea-Bissau: clinical and bacteriological findings, human immunodeficiency virus status and short term survival of hospitalized patients.

OBJECTIVE: To study tuberculosis patients in Guinea-Bissau with regard to clinical findings, bacteriologically verified diagnosis, human immunodeficiency virus (HIV) status and short term survival. DESIGN: 763 consecutive patients referred to the tuberculosis clinic with pulmonary symptoms underwent clinical examination and Ziehl-Neelsen sputum microscopy. Sputum for culture of mycobacteria on Löwenstein-Jensen medium was collected from all hospitalized patients, who were also screened by enzyme linked immunosorbent assay for the presence of HIV-1 and HIV-2 antibodies. HIV-positivity was confirmed by Western blot. RESULTS: 350 patients were diagnosed with tuberculosis and hospitalized. Adequate sputum samples were obtained from 301 patients, of whom 184 (61%) were positive on direct microscopy and the remaining 116 patients were diagnosed from clinical findings. Mycobacterium tuberculosis was cultured from 184 patients and M. avium in 16 patients, whereas in 101 patients the culture was negative. HIV-1 antibodies were found in 3.0%, HIV-2 antibodies in 16.4%, and dual infections in 2.0%. These figures, however, did not differ significantly from those of randomly selected age and sex matched controls. The prevalence of HIV-antibodies was statistically as common in patients with culture verified tuberculosis as in patients with clinically defined tuberculosis. Clinical acquired immunodeficiency syndrome was commonly diagnosed (80/301 patients) but significantly more often in HIV-positive, culture-positive tuberculosis patients, as were weight loss and lymphadenopathy. There was no statistical difference in short-time survival rate between the various patient groups. CONCLUSION: The diagnostic criteria applied, which are generally used in developing countries, identified most patients with pulmonary tuberculosis; however, a substantial number of patients are treated for tuberculosis without definite diagnostic criteria. The prevalence of HIV-infection was high but statistically no significant difference was demonstrated between the patient groups, controls and patients hospitalized for diseases other than tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Direct detection of Mycobacterium tuberculosis in sputum samples from Guinea Bissau by an rRNA target-amplified test system.

SETTING: There is a need for more sensitive and rapid methods for laboratory confirmation in the diagnosis of tuberculosis. OBJECTIVE: To investigate the applicability of a target rRNA amplified test system (AMTDT, Gen-Probe, CA) for rapid detection of Mycobacterium tuberculosis. DESIGN: The rRNA amplified test system was compared to standard methods for acid fast microscopy and mycobacterial culture for the demonstration of M. tuberculosis in sputum samples from 247 patients in Guinea Bissau with suspected tuberculosis. RESULTS: The highest incidence of positive samples was obtained with the AMTDT test. Out of 274 sputum samples 96 (35%) were positive by the AMTDT test, 82 (30%) were positive by culture and 38 (14%) by direct microscopy. Using culture as reference method the sensitivity of the test was 85% (after discrepancy analysis 87%), and the specificity was 86% (after discrepancy analysis 93%). CONCLUSION: The sensitivity and specificity of the AMTDT test used in this setting indicates that it may be a valuable complement for improving the laboratory diagnosis of tuberculosis.

Bacteriological Techniques↗
PubMed1996

Proliferation of distinct human T cell subsets in response to live, killed or soluble extracts of Mycobacterium tuberculosis and Myco. avium.

The proliferative responses of distinct cell subsets from healthy, bacille Calmette-Guérin (BCG)-vaccinated blood donors were assessed after in vitro stimulation with live or UV-killed Mycobacterium tuberculosis and Myco. avium or with soluble extracts obtained from either mycobacterial species. Proliferation of cell subsets was evaluated by flow cytometric determination of 5-bromo-2'-deoxy-uridine incorporation into DNA and simultaneous identification of surface phenotypic markers. In the presence of monocytes, the response to whole (live or killed) bacteria was characterized by a predominant proliferation of CD4+ alphabeta+ T cells and, to a lesser extent, of CD8+ alphabeta+ T cells. Proliferation of CD8+ alphabeta+ T cells was primarily elicited by live rather than killed bacilli (P < 0.05). Conversely, when soluble bacterial extracts were used as stimulators, a preferential proliferation of gammadelta+ T cells, expressing predominantly Vgamma9+ and Vdelta2+ T cell receptor chains, was recorded. Moreover, when monocyte-depleted cell populations were directly cultured with live bacteria, a marked proportion of CD3- CD16+ (natural killer (NK)) cells was detected among the responding cells. Although both alphabeta, gammadelta and NK cells have been previously shown to react with mycobacteria in vitro, their relative contributions to the response have been difficult to assess. Using a flow cytometric technique which allows direct identification of proliferating cells within complex cell populations, our study demonstrates significant differences in the ability of various mycobacterial antigen preparations to elicit proliferation of distinct cell subsets.

Antigens, Bacterial↗
PubMed1996

Immunohistochemical studies of proinflammatory cytokines and their receptors in hair follicles of normal human skin.

Immunoreactivity to interleukin-1 alpha, interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha and their receptors, as well as the endogenous interleukin-1 receptor antagonist, was investigated in hair follicles in paraffin-embedded normal human skin. Interleukin-1 beta- and tumour necrosis factor-alpha-like immunoreactivities were found in the inner root sheath layer of hair follicles, at the suprapapillary level. Interleukin-1 receptor-like immunoreactivity was also found in this layer, while there was a variable immunoreactivity to the interleukin-1 receptor antagonist. In the outer root sheath there was a weak to moderate staining for the four cytokines, in addition to intense staining for their receptors and a weak staining for the antagonist. The fibrous root sheath had a moderate immunoreactivity for interleukin-1 alpha and interleukin-6. The distribution patterns suggest that these cytokines, particularly interleukin-1 beta and tumour necrosis factor-alpha, may have a protective role in hair formation, while all the investigated proinflammatory cytokines may have a role in the differentiation process.

Adult↗
PubMed1996

Antimycobacterial synergism of clarithromycin and rifabutin.

Clarithromycin and rifabutin are among the most promising drugs for the therapy of infections caused by Mycobacterium avium or other atypical mycobacteria. Since synergism of combined drugs is important in order to achieve strong antimycobacterial activity, the combined inhibitory effects of antibacterial agents should also be investigated when agents are evaluated for possible use in antimycobacterial drug therapy. In the present study we examined the antimycobacterial activity of clarithromycin, rifabutin, and their combination against 51 clinical isolates of the M. avium complex from patients with acquired immune deficiency syndrome (AIDS) with disseminated mycobacteriosis. A concentration-dependent inhibition was seen for each drug. The antibacterial effect was significantly more pronounced for the combined drugs than for the agents tested separately. Synergism, against up to 88% of the strains tested, was seen for the tested drugs combined at different concentrations. All 51 M. avium strains were susceptible to the combination of 4 mg/l clarithromycin and 2 mg/l rifabutin.

AIDS-Related Opportunistic Infections↗
PubMed1995

Vaccination with a formalin-killed P-fimbriated E. coli whole-cell vaccine prevents renal scarring from pyelonephritis in the non-human primate.

A formalin-killed P-fimbriated Escherichia coli serotype O4 vaccine was evaluated for protective efficacy in monkeys in an experimental pyelonephritis model following urethral bacterial inoculation. The vaccination did not protect against initial colonization and there were no significant differences in the time of bacteriuria after experimental infection in the two groups of animals. The whole-cell vaccine offers a limited protection against renal dysfunction and scarring (p = 0.002) and less renal involvement (p = 0.04), results that are quite similar to those given by a synthetic O-antigen-specific saccharide-protein conjugate vaccine previously tested.

Analysis of Variance↗