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H Van Heuverswyn

Publications and source records attributed to H Van Heuverswyn.

At least 19 recordsLinked to original sources
PubMed2001

Evaluation of B7-1 (CD80) and B7-2 (CD86) costimulatory molecules and dendritic cells on the immune response in leprosy.

The cell activation depends on T cell antigen receptor binding to antigen plus MHC and costimulation. The binding of CD28, expressed on the T cell surface to B7 (B7-1 or CD80/B7-2 or CD86) present on the antigen--presenting cells (APCs), determines, in several T cell function models, if activation or anergy follows antigenic stimulation. In leprosy, the role of CD80 and CD86 as costimulatory signal in M. leprae-specific cellular immunity has not yet been defined. We investigated the role of B7-CD28 pathway of T cell activation in the in vitro response to M. leprae, following stimulation in the presence of monocytes or dendritic cells (DCs) as APCs. Monocytes were purified, by cold aggregation, from peripheral blood mononuclear leukocytes (PBMC), isolated from leprosy patients. In order to obtain DCs, the monocytes were cultured in the presence of IL-4 and GM-CSF. T cells were purified from PBMC by negative selection with mABs and C'. The phenotype of the cell populations was monitored by FACS. Lymphoproliferative assays were performed with T cells, in the presence of monocytes or DCs. The cells were stimulated by M. leprae in the presence of anti-CD80 antibody (Ab) and/or anti-CD86 antibody (Ab) (Innogenetics). In some experiments Il-10, Il-12 and anti-Il-12 Ab were also added to the culture. We observed a significantly more efficient APC function for DCs when compared to monocytes in T cell in vitro responses to M. leprae. Regardless of the clinical form of Leprosy, the M. leprae-specific immune response was markedly reduced in the presence of anti-CD86 Ab. Il-12 increase the immune response to M. leprae while IL-10 or anti-IL-12 Ab reduce this response when monocytes or DCs were used as APCs.

Antigen-Presenting Cells↗
PubMed1999

Shedding of soluble receptor for tumor necrosis factor alpha induced by M. leprae or LPS from human mononuclear cells.

Cell surface expression and release of the tumor necrosis factor receptor (TNFR type I) was analyzed after stimulation of peripheral blood mononuclear cells (PBMC) with Mycobacterium leprae (M. leprae) or lipopolysaccharide (LPS). A transient spontaneous expression of TNFR type I on the surface of PBMC was observed. Two hr after activation with LPS, a significant reduction of TNFR type I expression was detected: Release of TNFR type I by M. leprae or LPS-stimulated PBMC was evaluated with an enzyme-linked immunoabsorbent assay. This release occurred relatively later (20 to 40 hr) than the secretion of TNF alpha which reached high levels between 8 to 20 hr after activation. Thalidomide, a potent drug for the treatment of erythema nodosum leprosum episodes by inhibiting TNF alpha production, had no influence on the TNFR type I expression. Similar results were obtained with pentoxifylline. It is concluded that the release of TNFR type I by M. leprae or LPS-stimulated PBMC may counteract the pro-inflammatory activities of TNF alpha, by reducing the systemic toxicity of this cytokine in leprosy.

Cells, Cultured↗
PubMed1993

Polyphasic taxonomy leading to the proposal of Moraxella canis sp. nov. for Moraxella catarrhalis-like strains.

The taxonomic position of a group of 16 Moraxella catarrhalis-like strains, isolated mainly from dogs, was examined by using morphological tests, biochemical tests, serology, ribotyping with oligonucleotide probes, polymerase chain reaction typing of the 16S rRNA gene and the 16S-23S rRNA gene spacer region, polyacrylamide gel electrophoresis of total proteins, fatty acid profiles, moles percent G+C, dot spot and in-solution DNA-DNA hybridizations, and DNA-rRNA hybridizations. It was found that these organisms constitute a distinct cluster within the genus Moraxella. Since they differ genotypically as well as phenotypically from previously described Moraxella species, a new species, Moraxella canis, is proposed to accommodate these isolates. The type strain is LMG 11194 (= N7 = CCUG 8415A).

Animals↗
PubMed1993

Typing of hepatitis C virus isolates and characterization of new subtypes using a line probe assay.

A reverse-hybridization assay, the line probe assay (LiPA), based on variations found in the 5' untranslated regions of the different hepatitis C virus (HCV) genotypes was developed, permitting simple and fast determination of four HCV genotypes and their subtypes. Using this assay, 61 PCR-positive Brazilian HCV sera were typed. Of the sera, 33% had a type 1 HCV infection, 38% had type 1b (related to HCV-J), 1.5% had type 2a (related to HC-J6), 24.5% had type 3 (related to E-b1 and HCV-T), and 3% of the sera were co-infected. This assay format was further evaluated using 13 sera from Belgium and the Netherlands, and all of these could be classified. Two pools of Japanese sera were classified as either type 2a or were co-infected with types 1b and 2a, but no type 2b sequences were detected. Another eight PCR-positive sera were obtained from Burundi and Gabon. The sequence of the 5' untranslated region of these African viruses was strongly divergent from the three previously described types. Therefore, these isolates were tentatively classified as type 4. These and some of the other non-type 1 sera often demonstrated weaker reactivities than type 1 isolates in currently used second generation antibody confirmation assays.

Base Sequence↗
PubMed1993

Preparation of a specific RNA probe for detection of Mycobacterium paratuberculosis and diagnosis of Johne's disease.

A species-specific recombinant clone (F57) was obtained from a genomic library of Mycobacterium paratuberculosis in the transcription vector pGem 3Z. This clone proved to be specific for all mycobacteria tested, including M. avium, and was able to recognize all of the tested M. paratuberculosis strains isolated from animals and humans (patients with Crohn's disease). The F57 insert was sequenced and a segment of 620 bp with a G + C content of 58.9% was identified. Comparison of the sequence with sequences in the EMBL and UGEN data banks revealed the uniqueness of the F57 sequence, which had no resemblance to other known genes.

Animals↗
PubMed1991

The development of specific rRNA-derived oligonucleotide probes for Haemophilus ducreyi, the causative agent of chancroid.

Part of a ribosomal ribonucleic acid (rRNA) cistron of Haemophilus ducreyi was enzymically amplified using conserved primers within the rRNA molecules, cloned in a plasmid vector, and sequenced. From the nucleotide sequence, eight oligonucleotides complementary to different regions in the 16S and 23S rRNA molecules were selected, chemically synthesized, and used as hybridization probes. Hybridization experiments with at least 41 H. ducreyi strains and 13 or 14 non-H. ducreyi strains revealed that all eight oligonucleotide probes were highly reliable and completely specific for H. ducreyi strains. Comparisons of 16S rRNA sequences confirm that H. ducreyi is a member of the Pasteurellaceae though not closely related to other species in this family.

Base Sequence↗
PubMed1991

Confirmation and differentiation of antibodies to human immunodeficiency virus 1 and 2 with a strip-based assay including recombinant antigens and synthetic peptides.

We evaluated the use of the INNO-LIA HIV-1/HIV-2 Ab test (LIA HIV; Innogenetics) for the confirmation of antibodies to human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2). The test includes three recombinant HIV-1 proteins: p24 (gag), p17 (gag), and endonuclease (p31; pol), in combination with two synthetic peptides derived from the env gene of HIV-1 and one synthetic peptide selected from the env gene of HIV-2. Analysis of 450 sera from blood donors, 220 sera from patients with non-HIV pathology, and 28 Western blot (WB) p24-only reactive sera revealed no false-positive results, and the rate of indeterminate results was substantially lower than that with WB. Testing of 334 WB-confirmed HIV antibody-positive sera (309 HIV-1; 25 HIV-2) revealed no false-negative results. In two of seven seroconversion panels tested, LIA HIV detected the presence of HIV antibodies before WB did. In the other five panels, LIA HIV and WB confirmed the presence of HIV antibodies in the same sample. The LIA HIV assay therefore appears well suited for routine confirmation of the presence of HIV-1 and HIV-2 antibodies.

Antibodies, Viral↗
PubMed1990

Evaluation of an rRNA-derived oligonucleotide probe for culture confirmation of Neisseria gonorrhoeae.

The reliability of an rRNA-derived oligonucleotide probe for Neisseria gonorrhoeae was tested with 187 N. gonorrhoeae isolates, 81 Neisseria meningitidis isolates, and several strains of other bacterial species. The probe proved to be 100% specific and 100% sensitive. N. gonorrhoeae cells could also be reliably identified in contaminated cultures with the oligonucleotide probe. The 2.6-megadalton cryptic plasmid used as a probe for N. gonorrhoeae was shown to be less sensitive, detecting 179 of 181 N. gonorrhoeae isolates.

DNA Probes↗
PubMed1990

Generation and characterization of a neutralizing rat anti-rmTNF-alpha monoclonal antibody.

A rat anti-recombinant mouse tumour necrosis factor-alpha (rmTNF-alpha) monoclonal IgM antibody (1F3F3) with high specific binding activity for rmTNF-alpha was generated. The 1F3F3 monoclonal antibody (mAb) neutralizes the cytotoxic activity in vitro of rmTNF-alpha on L929 cells and inhibits the binding of radiolabelled rmTNF-alpha to its putative receptor on L929 cells. The 1F3F3 mAb binds to monomeric, dimeric and trimeric rmTNF-alpha and does not bind to reduced rmTNF-alpha, indicating that the recognized epitope is sensitive to denaturation. Using the 1F3F3 mAb as a capturing antibody and a biotinylated anti-rTNF-alpha as a detecting antibody, we have developed a sandwich ELISA that can specifically detect biologically active mTNF-alpha with a detection limit of 10 pg mTNF-alpha/well. This assay correlates well with the classical L929 cristal violet assay for the detection of bioactive rmTNF-alpha in biological fluids. The 1F3F3 mAb inhibits various in vitro biological activities of the rmTNF-alpha, such as the TNF-alpha-mediated tumoricidal activity of activated macrophages, the rmTNF-alpha-dependent stimulation of neutrophil degranulation and the growth-promoting effect of rmTNF-alpha. In vivo the 1F3F3 mAb inhibits lipopolysaccharide (LPS)-induced endotoxic shock. In conclusion, the 1F3F3 mAb is a useful tool to probe rmTNF-alpha activity both in vitro and in vivo.

Animals↗
PubMed1985

Molecular cloning of mouse tumour necrosis factor cDNA and its eukaryotic expression.

Tumour necrosis factor (TNF), released by induced macrophages, causes tumour necrosis in animals and kills preferentially transformed cells in vitro. mRNA induced in the established mouse monocytic PU 5.1.8 cell line by lipopolysaccharide, was converted into double-stranded cDNA and cloned in the pAT153 vector. Recombinant plasmids were screened by plus-minus hybridization and TNF-specific oligonucleotide probes constructed on the basis of partial amino acid sequences of rabbit TNF. A series of TNF specific clones were identified and confirmed by hybrid selection of mouse TNF-specific mRNA. The sequence codes for a 235 amino acids long polypeptide, of which 156 amino acids presumably correspond to the mature product. It can be concluded that mature mouse TNF is a glycosylated dimer. Biologically active TNF was secreted by both Cos-I and CHO-cells transfected with the chimaeric expression vector pSV2d2-mTNF containing the coding region of the mouse TNF cDNA gene.

Amino Acid Sequence↗
PubMed1982

Molecular cloning of human immune interferon cDNA and its expression in eukaryotic cells.

Starting with mRNA derived from Staphylococcal enterotoxin A induced human splenocytes, dsDNA was synthesized and inserted into unique BamHI site of the eukaryotic expression vector pSV529 (1). A recombinant plasmid containing human immune interferon (IFN-gamma) cDNA was identified by hybridization of plasmid inserted DNA bound onto nitrocellulose filters with mRNA derived from SEA-induced splenocytes, translation of the eluted RNA in Xenopus laevis oocytes and assaying for IFN activity. Plasmids containing the entire human IFN-gamma cDNA sequence were identified by colony hybridization and were sequenced. A unique coding region was identified which predicted a protein of 166 amino acids, the 20 N-terminal amino acids of which presumably represent a signal peptide. After transfection of monkey cells with plasmid DNA isolated from one of the recombinant clones (pHIIF-SV-gamma 1), IFN was excreted into the culture medium. This IFN was not distinguishable from human IFN-gamma by serological criteria or by cell target species specificity.

Amino Acid Sequence↗
PubMed1980

Recognition sequence for the restriction endonuclease BglI from Bacillus globigii.

Restriction endonuclease BglI recognizes the DNA sequence (Formula: see text) and cleaves each strand at the site indicated, thus generating 3' protruding ends. The recognition sequence was deduced by correlating mapping data with nucleotide sequence information and the position of cleavage was unambiguously determined by 32P labeling of 5' termini produced by BglI digestion.

Bacillus↗
PubMed1980

Nucleotide sequence of simian virus 40 DNA: structure of the middle segment of the HindII + III restriction fragment B (sixth part of the T antigen gene) and codon usage.

We report here the nucleotide sequence of the simian virus 40 DNA region that lies between the EcoRII restriction endonuclease cleavage sites at map positions 0.214 and 0.281. The sequence was determined by partial chemical degradation of terminally labeled DNA fragments according to the procedure of Maxam and Gilbert. This region represents 6.7% of the SV40 genome and is located in the middle of HindII + III restriction fragment B. It is expressed as part of the early 19-S messenger RNA, which codes for the large-T antigen protein. Only one open reading frame for translation can be deduced from the message strand of the DNA and this reading frame connects in phase with the one of both neighboring fragments. This publication is the last in a series of papers about the T-antigen gene, and several properties of this gene and its product are discussed. The non-randomness of codon usage is similar to that previously discussed for the late part of the genome. Moreover, it appears that the choice of a third letter can be determined by the nature of the following codon; some codons which start with a pyrimidine are almost never preceded by an adenosine and some ANN-type codons are almost never preceded by a guanosine.

Amino Acid Sequence↗
PubMed1979

Nucleotide sequence of the Hind-C fragment of simian virus 40 DNA. Comparison of the 5'-untranslated region of wild-type virus and of some deletion Mutants.

We report here the nucleotide sequence of the wild-type simian virus 40 (strain 776) restriction fragment Hind-C-P1 DNA and of the homologous region of various mutant DNAs which lack part of this fragment. During this work, we detected between EcoRII fragments N and G an additional, 17-base-pair EcoRII fragment, fragment P, which had previously been overlooked. Also, an additional dTpdG dinucleotide at residues L 339--340 was observed by sequence analysis of the DNA minus (E) strand; the presence of this dinucleotide was masked on sequencing patterns of the plus strand due to the persistence (during gel electrophoresis) of some secondary structures in the strand's 5'-terminal region. These nucleotide additions raise the total length of SV40 DNA to 5243 base pairs. The longest tandemly repeated segment in SV40 DNA now extends over 72 base pairs. SV40 deletion mutants dl 893 and dl 894 and SV40 strains Rh 911 and 1801 all lack an identical 72-base-pair-long DNA segment in the Hind-C region. This deletion corresponds precisely to one of the two aforementioned large tandemly repeated sequences. Mutant dl 895 lacks 66 base pairs, 63 of which are part of the former repetition. All these mutants, except dl 895, very probably were generated by an intramolecular, homologous recombination event. The 40-base-pair deletion in mutant dl 1811 includes the major capping site of SV40 late RNA. dl 1812 lacks only three base pairs, which are part of the overlapping HhaI and HpaII restriction sites at position 0.725--0.726.

Base Sequence↗