Detoxified Haemophilus ducreyi cytolethal distending toxin and induction of toxin specific antibodies in the genital tract.

Haemophilus ducreyi causes genital ulceration (chancroid), a sexually transmitted infection and still an important factor which contributes to the spread of HIV in developing countries. The bacterium produces a cytolethal distending toxin (HdCDT) causing cell cycle arrest and apoptosis/necrosis of human cells and contributes to the aggravation of ulcers. The aim of the study was to induce toxin-neutralizing antibodies in the genital tract of mice.

Toxic activity of the CdtB component of Haemophilus ducreyi cytolethal distending toxin expressed from an adenovirus 5 vector.

The Haemophilus ducreyi cytolethal distending toxin (HdCDT) catalytic subunit CdtB has DNase-like activity and mediates DNA damage after its delivery into target cells. We constructed a replication-deficient adenovirus type 5 (Ad5) vector expressing CdtB and investigated the toxic properties of this vector on HeLa cells. Ad5CdtB caused loss of cell viability, morphologic changes, and cell cycle arrest, findings similar to HdCDT intoxication.

Immunogenic and adjuvant properties of Haemophilus ducreyi lipooligosaccharides.

Haemophilus ducreyi, the chancroid-causing bacterium, produces lipooligosaccharides (HdLOS) that comprise 5-11 partially sialylated monosaccharides. Subcutaneous immunisation of mice with 5 microg of HdLOS purified from H. ducreyi strains 4438 and 7470 induced high levels of anti-HdLOS IgG.

Formaldehyde treatment increases the immunogenicity and decreases the toxicity of Haemophilus ducreyi cytolethal distending toxin.

Haemophilus ducreyi cytolethal distending toxin (HdCDT) is a tripartite AB toxin, which causes DNA damage in affected cells. We investigated the effects of formaldehyde on the chemical, biological, and immunological properties of the HdCDT complex, which was purified by immobilizing the glutathione S-transferase (GST)-CdtB fusion protein, followed by binding of the CdtA and CdtC recombinant proteins. The HdCDT was treated with increasing concentrations of formaldehyde in the presence of lysine.

The cytolethal distending toxin of Haemophilus ducreyi aggravates dermal lesions in a rabbit model of chancroid.

Haemophilus ducreyi, the etiologic agent of the sexually transmitted disease chancroid, produces a cytolethal distending toxin (HdCDT) that inhibits cultured cell proliferation, leading to cell death. A rabbit model of dermal infection was used to investigate the roles of H. ducreyi bacteria and HdCDT in the development, clinical appearance, and persistence of infection.

Induction of apoptosis/necrosis in various human cell lineages by Haemophilus ducreyi cytolethal distending toxin.

We investigated the impact of highly purified Haemophilus ducreyi cytolethal distending toxin (HdCDT) on the apoptosis and necrosis of various human cells; including myeloid cells, epithelial cells, keratinocytes, and primary fibroblasts. The levels of apoptosis and necrosis induced in these cells were compared to those induced by HdCDT in human T cells and in the Jurkat T cell line. Levels of caspase-3 activity were measured, and membrane changes like phosphatidylserine (PS) translocation was evaluated after double-staining with the fluorescein isothiocyanate (FITC)-labeled annexin V and propidium iodide (PI) using flow cytometry.

Specificity of antibodies directed against the cytolethal distending toxin of Haemophilus ducreyi in patients with chancroid.

Antibodies specific for the cytolethal-distending toxin of Haemophilus ducreyi (HdCDT) complex and for the CdtA, CdtB, and CdtC components were measured by ELISA in the sera of 50 patients with culture and/or PCR proven chancroid, 42 patients with periodontitis, 50 blood donors from Tanzania, 50 blood donors from Sweden. In addition, the biological activity e.g.

Etiology of genital ulcer disease and association with human immunodeficiency virus infection in two tanzanian cities.

Background: The etiological agent is usually not established in cases of genital ulcer disease (GUD) in Tanzania, since diagnosis and treatment of this disease are based mainly on clinical rather than microbiologic parameters. GUD increases the risk of infection with HIV. However, the association between specific GUD infections and HIV infection has not been fully investigated.

Toxicity and immunogenicity of purified Haemophilus ducreyi cytolethal distending toxin in a rabbit model.

The cytolethal distending toxin of Haemophilus ducreyi (HdCDT) is a three-component toxin that induces the arrest of the mammalian cell cycle in the G2 phase. All of the individual gene products, CdtA, CdtB and CdtC, are required for toxic activity on cultured mammalian cells. The CdtB component alone exerts nuclease activity.

In vitro and in vivo interactions of Haemophilus ducreyi with host phagocytes.

We investigated the phagocytosis of Haemophilus ducreyi both in vitro and in vivo. Human granulocyte and monocyte phagocytosis of opsonized and nonopsonized, fluorescence-labeled H. ducreyi was assessed by flow cytometry.