Publications by authors named "Manfred P Dierich"

Background: Control of HIV is suggested to depend on potent effector functions of the virus-specific CD8(+) T-cell response. Antigen opsonization can modulate the capture of antigen, its presentation, and the priming of specific CD8(+) T-cell responses.

Objective: We have previously shown that opsonization of retroviruses acts as an endogenous adjuvant for dendritic cell (DC)-mediated induction of specific cytotoxic T lymphocytes (CTLs).

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Background: The complement system is tightly controlled by several regulators. Two of these, factor H (FH) and C4b-binding protein (C4BP), can be acquired by pathogens conveying resistance to complement attack. The aim of the study was to characterize the FH binding molecule of Candida albicans, a potentially life-threatening yeast.

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Previous studies have demonstrated the involvement of complement (C) in induction of efficient CTL responses against different viral infections, but the exact role of complement in this process has not been determined. We now show that C opsonization of retroviral particles enhances the ability of dendritic cells (DCs) to induce CTL responses both in vitro and in vivo. DCs exposed to C-opsonized HIV in vitro were able to stimulate CTLs to elicit antiviral activity significantly better than non-opsonized HIV.

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Background: To determine the correlation between protection and humoral immune response against simian immunodeficiency virus (SIVmac251), 11 macaques were immunized with live-attenuated SIVmac239Deltanef either intravenously or via the tonsils and exposed to SIVmac251 after either 6 or 15 months along with unvaccinated controls.

Results: Independent of the route of vaccine application, viremia was significantly reduced in vaccinees compared with controls 2 weeks post-challenge. Concomitantly, viremia correlated inversely with SIV-specific IgG, complement-mediated lysis and neutralizing antibodies and these parameters seemed to contribute to reduced viremia.

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HLA-specific antibodies generated by allo-immunization are supposed to be involved in the control of HIV infections by both the neutralizing capacity of HLA-specific antibodies (Abs) and HLA-specific Ab-dependent complement-mediated lysis (CML). We further characterized CML of HIV primary isolates induced by HLA-specific Abs. Although HIV-specific and HLA allo-type specific Abs induced only weak CML of HIV primary isolates, several combinations of HLA allo-type specific Abs with HIV-specific Abs could enhance CML significantly.

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Zygomycosis is increasingly recognized in immunocompromised hosts. We investigated whether platelets become activated after contact with Zygomycetes and adhere to conidial and hyphal structures using immunofluorescence. The platelets' influence on fungal viability was evaluated by assessing hyphal elongation and hyphal damage.

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Article Synopsis
  • EHEC infections are a significant cause of hemolytic uremic syndrome (HUS), primarily due to the action of Shiga toxins (specifically Stx2), which are crucial in HUS development.
  • The study aimed to explore the role of the complement system, particularly its inhibitor factor H (FH), in EHEC-induced HUS, finding that Stx2 activates complement via the alternative pathway by binding to FH.
  • The research indicates that FH is important not only in atypical HUS but likely also in the pathogenesis of typical HUS caused by EHEC, highlighting the complexity of the immune response involved.
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Due to ongoing recombination and mutations, HIV permanently escapes from neutralizing antibody (nAb) responses of the host. By the masking of epitopes or shedding of gp120, HIV-1 further impedes an efficient neutralization by Abs. Therefore, nAbs responses of the host are chasing behind a rapidly evolving virus and mainly non-neutralizing antibodies (non-nAbs) are present in the host.

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Besides Shiga toxins (Stx), Stx-producing Escherichia coli (STEC) harbour several other putative virulence factors, including the serine protease EspP. We have investigated 214 STEC strains from Austria belonging to 61 different serotypes from humans, animals, and food for the presence of this serine protease gene and have determined the espP subtypes and their association with clinical outcome. espP was detected in 121 (57%) out of 214 strains.

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Cerebral aspergillosis is a mostly lethal infection of the central nervous system. Former results identified low cerebral complement levels as one cause for insufficient immune reaction. Therefore we studied cerebral complement expression after fungal invasion and investigated putative mechanisms of Aspergillus spp to cope with the complement-induced selection pressure.

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Using laser scanning microscopy, we investigated whether platelets are capable of internalizing Aspergillus conidia and examined Aspergillus-platelet adherence. The influence of platelets on fungal growth was evaluated by assessing galactomannan (GM) release, hyphal elongation, and colony size. A secretion assay with [(3)H]-serotonin (5-hydroxytryptamine [5-HT]) was performed.

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The in vitro activity of posaconazole plus amphotericin B against conidia and hyphae of 30 clinical zygomycetes was investigated. The combination of posaconazole with amphotericin B was found to be significantly more synergistic (40%) against hyphae (P < 0.05) than against conidia (10%).

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Secreted aspartic proteases (Saps) represent an important virulence factor facilitating fungal adherence. Several protease inhibitors (PIs), including HIV PIs, have been shown to reduce Candida adhesion. The aim of this study was to ascertain whether or not the recently discovered PIs Aureoquinone and Laccaridiones A and B, isolated from Basidiomycete cultures, or Bestatin, act as Sap-inhibitors and/or inhibitors of fungal adhesion.

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MICs and fractional inhibitory concentrations were evaluated for anidulafungin and voriconazole alone and in combination against conidia and hyphae under hypoxic (1% oxygen-5% CO(2)-94% nitrogen) conditions against 31 Aspergillus isolates. Anidulafungin exhibited excellent activity against conidia and hyphae of Aspergillus spp. The visual reading of the MIC for anidulafungin was optimal under hypoxic conditions.

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This study investigated the basis for intrinsic amphotericin B (AMB) resistance in Aspergillus terreus. The ergosterol content, cell wall composition, and lipid peroxidation level had no influence on AMB resistance. The level of catalase production in A.

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Upon crossing the endothelial barrier of the host, HIV initiates immediate responses of the immunity system. Among its components, the complement system is one of the first the first elements, which are activated to affect HIV propagation. Complement participates not only in the early phase of the immune response, but its effects can be observed continuously and also concern the induction and modification of the adaptive immune response.

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Article Synopsis
  • Shiga toxins (Stx) produced by Escherichia coli (STEC) are linked to serious illnesses like hemolytic uremic syndrome (HUS).
  • In a study of 201 STEC strains, stx(2) and stx(2c) alleles were found to be highly virulent and connected to HUS, while other alleles were associated with milder infections.
  • The research suggests that the specific stx genotype, rather than the quantity of Stx or its cytotoxic effects, may be more crucial in determining the risk of developing HUS.
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Outbreaks traced to bacterial contamination of multiple-dose vials are reported in the literature. During a four-month period, multi-dose vials (MDVs), single-dose vials (SDVs), and vials containing self-prepared admixtures were collected from various wards to analyse sterility of their contents. We examined 68 commercially available MDVs containing sodium chloride 0.

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Literature harbours several reports of potable water-associated outbreaks. We studied the prevalence of Shiga toxin- (stx1/2), intimin- (eae) and haemolysin (hlyA) genes in Escherichia coli isolates from drinking water of private and public water supplies in a rural area of Upper Austria; 2633 water samples were gained between November 2000 and December 2003. Two hundred and eighty of these water samples were positive for E.

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For the recruitment of dendritic cells (DC) to the site of infection, DC express several sensors for danger signals, such as receptors for C5a. This anaphylatoxin is generated upon complement activation. As HIV-1 triggers the complement cascade, we determined whether C5a is generated by the virus and tested the functional activity of C5a in migration and infection assays.

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Already at initial phases of infection, HIV is coated with complement fragments. During the chronic phase, when HIV-specific IgGs appear, the virus circulates immune complexed with IgG and complement. Thus, we studied the interaction of dendritic cells (DCs) and DC-T cell cocultures with complement (C)-opsonized and C-IgG-opsonized HIV.

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Rapid detection of enterohemorrhagic Escherichia coli is important for its successful treatment. We have evaluated the immunochromatographic Duopath Verotoxin-test for detection of Shiga toxins, in comparison with enzyme-linked immunosorbent assay and polymerase chain reaction, on 240 clinical human stool samples. The Duopath-test showed a lower sensitivity and specificity.

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Highly active antiretroviral therapy including HIV protease inhibitors has led to a marked reduction of clinically relevant mucosal candidiasis. We have previously shown that HIV protease inhibitors directly inhibit adhesion of Candida albicans to epithelial cells at concentrations that are reached in vivo during antiretroviral therapy. The aim of this study was to establish whether HIV protease inhibitors also inhibit adhesion of Candida to endothelial cells, which play a major role in systemic fungal disease.

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We investigated phagocytosis and intracellular killing of clinical and environmental isolates of Aspergillus spp. by human monocyte-derived macrophages (MDMs). Serial pathogens such as Aspergillus fumigatus, Aspergillus flavus and Aspergillus terreus were examined with a microbiological assay.

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