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Biomedical subjects

G Maertens

Publications and source records attributed to G Maertens.

51 records · Page 3Linked to original sources
PubMed1994

Cloning and phylogenetic analysis of the core, E2, and NS3/NS4 regions of the hepatitis C virus type 5a.

By means of the Line Probe Assay, a hepatitis C virus type 5a infected serum from a Belgian patient was selected. The complete core region (573 bp), the carboxyterminal part of E1 and the aminoterminal part of E2/NS1 (661 bp), and an epitope containing region in NS3-NS4 (1452 bp) were cloned and sequenced. The deduced amino acid sequence revealed type-specific variations in regions of core and NS4 which were previously recognized as evoking a type-specific antibody response. In addition, the aminoterminal region of E2 showed high variability when compared with sequences of type 1, 2, and 3. Phylogenetic analysis showed separate branching of this isolate. The analysis in the core region was not conclusive for some of the strains included and should therefore be carried out in combination with the NS5B region.

Amino Acid Sequence↗
PubMed1994

Genotypic analysis of hepatitis C virus in American patients.

We examined hepatitis C virus genotypes in 98 American patients with chronic hepatitis C virus infection by means of two methods; restriction fragment length polymorphism analysis and line probe assay, which is based on type-specific sequence variations in the 5' untranslated region. Type 1 was present in 73 patients (74%), type 2 in 15 (15%), type 3 in 6 (6%) and type 4 in 1 (1%). Line probe assay further subdivided type 1 into 1a (n = 35) and type 1b (n = 37) and type 2 into type 2a (n = 6) and 2b (n = 9). Two patients (2%) had both restriction fragment length polymorphism and line probe assay evidence of dual infection (with types 1 and type 2) while another case had both type 1a and 1b by line probe assay. One patient was untypable by either technique. There was no correlation between infecting genotype and presumed cause, serum indexes of necroinflammatory activity, or age or sex of the patients studied or known duration of infection. Patients with type 2 hepatitis C virus had more severe liver disease histologically (p = 0.0027) compared with other genotypes but, paradoxically, had significantly lower levels of circulating hepatitis C virus RNA (12.1 +/- 12.8 x 10(5) genome equivalents/ml) than other types (36.4 +/- 44.8 x 10(5) genome equivalents/ml, p < 0.001). Response to interferon was less likely to be sustained in patients infected with type 1 than in those infected with other types (7% vs. 40%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Chi-Square Distribution↗
PubMed1994

Rapid detection of hepatitis C virus RNA by direct capture from blood.

A new diagnostic assay for hepatitis C virus RNA detection is described. HCV genomic RNA is captured onto streptavidin-coated magnetic beads by solution hybridization with biotinylated complementary oligonucleotides. The specificity of the capture assay is confirmed using different capture oligonucleotides as well as sera representing different types of HCV. Sensitivity was determined by testing serial dilutions of a HCV infected plasma. A panel of 50 sera was tested for anti-HCV by a Line Immunoassay and for HCV-RNA by both a conventional guanidinium extraction method and the new capture assay. The specificity of the capture assay was 95.8% and the sensitivity was 92.3% compared to the standard protocol. This method provides a rapid and simple alternative for HCV-RNA detection in blood samples.

Animals↗
PubMed1994

Analysis of hepatitis C virus genotypes by a line probe assay and correlation with antibody profiles.

The 5' untranslated regions derived from 54 patients with a chronic hepatitis C virus infection were analyzed to determine the (sub)type of hepatitis C virus. Labelled polymerase chain reaction products from 5' untranslated region were used as probes for reverse hybridization in a line probe assay (Inno-LiPA) and results were validated by comparison with direct sequencing data. Five different genotypes could be distinguished based on 5' untranslated region sequence diversity. Results of typing by line probe assay and direct sequencing were similar. Antibody responses against core, NS-3, NS-4 and NS-5 epitopes were detected by RIBA-4 and Inno-LIA HCVAb II confirmatory assays. There was no consistent correlation between genotype and anti-HCV responses, although types 2, 3 and 4 hepatitis C virus isolates show poor reactivity with NS-4 ep!%"pes.

Base Sequence↗
PubMed1994

Longitudinal analysis of hepatitis C virus infection and genetic drift of the hypervariable region.

Hepatitis C virus (HCV) infections in a cohort of chimpanzees were studied retrospectively. All animals had been inoculated intravenously with materials derived from a single-source chimpanzee plasma implicated in non-A, non-B hepatitis, prepared by extensive ultracentrifugation. Anti-HCV and HCV RNA were monitored by the confirmatory line immunoassay and by an RNA-capture polymerase chain reaction method, respectively. In a chronically infected chimpanzee, HCV RNA was detectable after 32 days and throughout the acute phase, dropped transiently below detection level, and became detectable again. In 3 other chimpanzees with acute resolving infections, HCV RNA was detected 7-11 days after inoculation and became permanently undetectable after alanine aminotransferase normalization. Various anti-HCV profiles were detected among the chimpanzees. Analysis of the hypervariable region in E2/NS1 in 7 chimpanzees suggested genome stability on transmission, revealed different mutation frequencies during chronic infection, and suggested the importance of immune selection during chronic HCV infection.

Amino Acid Sequence↗
PubMed1993

Analysis of the putative E1 envelope and NS4a epitope regions of HCV type 3.

Using a Line Probe Assay, type 3 HCV genotype-infected sera were selected from Brazilian blood donors. The partial nucleotide sequences of the core/E1 and NS4a epitope-containing regions and the NS5b typing region were determined. The E1 region had a nucleic acid homology of only 61 to 65% with the type 1 prototype genomes, and 56 to 58% homology with the type 2 prototype HCV genomes. Similar homologies were also found for the NS4a epitope region and for NS5. Furthermore, the deduced amino acid sequence of type 3 NS4a was used to generate synthetic peptides which were strongly reactive with human HCV-infected sera which were previously determined as anti-NS4 negative, indicating that a type-specific antibody response to the NS4a protein may exist.

Amino Acid Sequence↗
PubMed1993

Recombinant secreted haemagglutinin protects mice against a lethal challenge of influenza virus.

Balb/c mice were immunized with 2 x 2 micrograms of purified recombinant secreted haemagglutinin, derived from the A/Victoria/3/75 (H3N2) virus. In the first immunization, Ribi adjuvant was used, while for the booster injection a monophosphoryl lipid A/muramyl dipeptide combination was chosen. Mice immunized in this way were 90-100% protected against a challenge with 20 LD50 of mouse-adapted, homologous virus (strain X47). Bromelain-solubilized haemagglutinin gave only 70% protection under comparable conditions.

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

Prevalence of anti-hepatitis C virus in the blood donor population of Rio de Janeiro.

The prevalence of hepatitis C virus (HCV) antibodies in 2,557 asymptomatic volunteer Brazilian blood donors is reported. Using the line immunoassay (Inno-LIA) as a confirmatory test on ELISA anti-HCV-positive reacting sera, a prevalence rate of 2.7% for anti-HCV positivity was found. By comparison, prevalences of 1.6% for hepatitis B surface antigen, 0.9% for Treponema pallidum, 0.4% for human immunodeficiency virus and 0.04% for Trypanosoma cruzi were observed. Only 57% of the HCV-positive donors had elevated alanine aminotransferase (ALT) levels. Using previous criteria, based on surrogate markers (ALT > or = 50 IU/l and for anti-hepatitis B core antibody), for HCV infection at that time, only 25% of the HCV-positive donations would have been eliminated. In view of the high prevalence of anti-HCV reactivity among the Brazilian blood donor population and the poor reliability of surrogate markers, it is recommended that routine screening for anti-HCV in Brazilian blood donors is introduced.

Alanine Transaminase↗
PubMed1992

Hepatitis C virus antibody detection by a line immunoassay and (near) full length genomic RNA detection by a new RNA-capture polymerase chain reaction.

A rapid and simple RNA-capture polymerase chain reaction assay (RCPA) for detection of hepatitis C virus (HCV) is described. The assay detects specifically the presence of (near) full length genomic RNA of HCV by capturing HCV-RNA at the 3' terminal end on magnetic beads, followed by cDNA synthesis and PCR with 5' end specific primers. Sera were obtained from 30 chimpanzees inoculated with non-A, non-B hepatitis material from various sources, 28-122 months after infection. The sera were tested for the presence of HCV-RNA by RCPA and for HCV antibodies by a Line ImmunoAssay (Inno-LIA HCV Ab). Both tests were compared and show a high degree of agreement. Screening of 30 chimpanzee sera revealed either clearing of the virus below detection level (22/30) or development of a HCV carrier state (8/30). Only 1 of 11 LIA-indeterminate samples was positive by RCPA. As the RCPA is more sensitive, it can be used to test for the presence of HCV in sera which are classified indeterminate by the LIA. The outcome of the infection seems to be independent of the nature of the inocula, suggesting that the individual immune response could determine either clearing of the virus or the development of chronic infection.

Animals↗
PubMed1989

The subcellular localization of the neu protein in human normal and neoplastic cells.

We have examined the subcellular localization of the neu protein by immunohistochemistry and immuno-electron microscopy, associated with immunoblotting of normal and neoplastic tissues with 2 monoclonal antibodies (MAbs). Immunoelectron microscopy clearly reveals that neu protein resides only on the lateral plasma membrane of the simple epithelium of the breast and on the plasma membrane of malignant breast cells. It is also found on the membranes of the microvilli and the apical vacuoles of the cells of the proximal convoluted tubule of the kidney. In the cytoplasm, the only immunoreactivity detected with both antibodies was on the membrane of the mitochondrial cristae of normal and malignant cells. Immunoblotting reveals that the molecular weight of the membrane protein is 185 and 155 kDa for the mitochondrial protein. The cell membrane staining pattern can be revealed by light microscopic immunohistochemistry only in malignant cells and is therefore specific for malignancy. The membrane expression in normal cells cannot be visualized in this way. The mitochondrial reactivity appears as a cytoplasmic granular staining when examined under the light microscope. Similar cytoplasmic staining has been described previously in other studies with other antibodies against the neu protein and has lead to speculation about its function in normal and malignant cells. However, it is demonstrated in this study that it is not the known neu-oncogene product.

Antibodies, Monoclonal↗
PubMed1989

The expression of the neu oncogene product in breast lesions and in normal fetal and adult human tissues.

The expression of the neu oncogene product was investigated in invasive and non-invasive ductal carcinomas of the breast, non-neoplastic lesions of the breast, fragments of normal adult and fetal breasts and in several other normal and fetal tissues at different weeks of pregnancy by means of an immunohistochemical study with monoclonal antibodies. The staining pattern along the cytoplasmic membrane was specific for malignancy and occurred in 29% of the breast carcinomas. It was observed in invasive carcinomas as well as in ductal carcinoma in situ and it showed a significantly higher expression in premenopausal women than in postmenopausal women. This higher expression was also present in oestrogen receptor-negative tumours. The tubules of the fetal and adult kidney, the absorption cells of the fetal and adult small and large intestine, the sebaceous glands of the fetal and adult small and large intestine, the sebaceous glands of the fetal and adult skin, the adult endocervix, the endometrium, the C-cells of the thyroid, hepatocytes and all ductal cells of the fetal breast showed a constant diffuse intracytoplasmic granular staining. staining. The same granular intracytoplasmic staining pattern was focally observed in rare cases of normal breast tissue in adults and in some cases of epitheliosis, aprocrine metaplasia and some breast carcinoma cells, which did not express neu oncogene product on their membrane. Western blot experiments showed that the cytoplasmic protein had a molecular weight of 155 kD (kilodaltons); the membrane protein is the known 185 kD neu protein.

Adult↗
PubMed1988

High-level transient expression of influenza virus proteins from a series of SV40 late and early replacement vectors.

We have constructed a collection of simian virus 40 (SV40) plasmid vectors useful for transient or constitutive expression of cDNA or genomic DNA in animal cells. Most vectors contain several unique restriction sites downstream from the SV40 late or early promoter, and are available with or without the virus-specific splicing signals. The use of these vectors for transient expression in monkey cells of X47 (H3N2) influenza hemagglutinin (HA) and matrix protein (M1) was demonstrated. Membrane-bound (HAm) as well as secreted forms of the HA glycoprotein lacking the sequence of the C-terminal anchor (HA-) have been obtained. Depending on the insert, the type of vector and the amount of transfected DNA, HA levels in COS cells [Gething and Sambrook, Nature 293 (1981) 620-625] transfected with late replacement SV40 vectors vary from 10(9) (HAm) to 10(8) (HA-) molecules per transfected cell. The maximum expression levels with early replacement vectors in COS cells are at least 50 times lower. In addition to the optimalization and the characterization of the expression of each vector-coded influenza protein, cotransfections, including vectors expressing HAm, neuraminidase (NA) and M1, were undertaken. The latter experiments did not result in a measureable amount of HAm or NA in the cell culture medium, suggesting that expression of these three structural viral proteins does not result in budding of (empty) influenza particles from the cell surface.

Antibodies, Viral↗
PubMedDate not supplied

High prevalence of hepatitis C infection among Brazilian hemodialysis patients in Rio de Janeiro: a one-year follow-up study.

Nearly 400 hemodialysis patients treated at 5 different hemodialysis units in Rio de Janeiro were tested for one year for the presence of hepatitis C and B markers. During the same period, samples were also obtained from 35 continuous ambulatory peritoneal dialysis (CAPD) patients and from 242 health care workers. Depending on the hemodialysis unit studied, anti-HCV prevalence rates ranging from 47% to 82% (mean 65%) were detected. CAPD patients showed a lower prevalence of 17%. The prevalence of antibodies against hepatitis C virus (anti-HCV) among health care workers was 2.9%. We observed a hepatitis C attack rate of 11.5% per year in the anti-HCV-negative hemodialysis patient population. An average of 9.4% of the hemodialysis patients were chronic carriers of hepatitis B virus (HBV) (range 1.8% - 20.4%), while 48.9% showed markers of previous HBV infection. The HBV attack rate was 4.5% per year (range 0% - 6%). These results indicate an alarming high prevalence of anti-HCV among hemodialysis patients of this studied region.

Brazil↗