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M Groenink

Publications and source records attributed to M Groenink.

34 records · Page 2Linked to original sources
PubMed1997

Potent inhibition of replication of primary HIV type 1 isolates in peripheral blood lymphocytes by negatively charged human serum albumins.

We previously reported the antiviral capacity of human serum albumin (HSA), which was modified by the introduction of a single (Suc-HSA) or two carboxylic groups (Aco-HSA) per lysine residue, yielding strongly negatively charged polypeptides. Here we report the antiviral effect of these modified HSAs on replication of primary HIV-1 isolates that differed with respect to syncytium-inducing (SI) capacity and cell tropism. Both Suc-HSA and Aco-HSA potently inhibited replication of primary HIV-1 variants, independent of the SI capacity of the HIV-1 variant, with IC50 values in the range of 50 to 187 microg/ml. The inhibition of the formation of syncytia and the absence of proviral DNA products in cells inoculated with HIV-1 in the presence of Suc-HSA or Aco-HSA pointed to interference at an early level in the virus replication cycle. The inhibitory capacity of Suc-HSA and Aco-HSA on primary HIV-1 variants suggests that these agents are potential candidates for use in antiviral therapy in HIV-infected individuals.

Anti-HIV Agents↗
PubMed1997

Rat ferritin-H: cDNA cloning, differential expression and localization during hepatocarcinogenesis.

Elevated serum ferritin levels, especially of the H subunit, accompany many clinical malignancies. By using the subtraction-enhanced display technique, we have recently isolated several cDNA clones which are over-expressed in rat hepatocellular carcinoma induced by diethylnitrosamine. One 830-base-pair clone was 88% similar to human ferritin-H cDNA and encoded a 182 amino acid protein which is 97% homologous to human ferritin-H chain. Hepatic mRNA levels of ferritin-H were increased markedly at the early stage of diethylnitrosamine-induced hepatocarcinogenesis in the rat (6 weeks) and appeared more than 10-fold overexpressed as the tumour progressed. In contrast, hepatic ferritin-H mRNA remained constant during liver regeneration after a 70% partial hepatectomy. In situ hybridization showed that over-expression of ferritin-H was exclusively localized to preneoplastic foci, to tumour nodules and to tumour cells invading blood vessels. These findings suggest that ferritin-H is a highly conserved protein, its over-expression during tumour development is phenotypically correlated with tumour initiation and/or progression, and it is useful as an early marker for hepatocellular carcinoma.

Animals↗
PubMed1995

Temporal relationship between elongation of the HIV type 1 glycoprotein 120 V2 domain and the conversion toward a syncytium-inducing phenotype.

The second and third variable domains (V2 and V3) of the human immunodeficiency virus type 1 (HIV-1) gp120 envelope molecule have been shown to be determinants of syncytium-inducing (SI) capacity. Previously we have reported evidence that increased length of the V2 domain and duplication or relocation of potential N-linked glycosylation sites in V2 might be used as prognostic markers for evolution toward an SI phenotype. Here, we used a PCR assay that discriminates a 6-nucleotide difference in the length of the V2 domain, with a sensitivity of 1 elongated V2 domain when present in a background of 125 to 625 short V2 domains. Analysis of DNA isolated directly from PBMCs from 11 HIV-1-infected individuals prior to SI phenotype conversion revealed, however, that the usefulness of this PCR for V2 length polymorphism as predictive marker for SI phenotype evolution is limited. The strong association as observed in our previous study between elongation of the V2 domain and an SI phenotype prompted us to expand our first analysis. An extremely significant correlation was observed between V2 length and virus phenotype for samples obtained at about the moment of SI conversion, but not for samples obtained 3 to 35 months after SI phenotype conversion, suggesting that changes in V2 may be only transiently required to allow SI phenotype evolution. This possibly only transient nature of V2 elongation may explain the discrepancy between results by our group and others.

Amino Acid Sequence↗
PubMed1995

Equal levels of gp120 retention and neutralization resistance of phenotypically distinct primary human immunodeficiency virus type 1 variants upon soluble CD4 treatment.

Human immunodeficiency virus type 1 (HIV-1) variants passaged in T-cell lines, often called laboratory isolates, are potently neutralized by soluble CD4 (sCD4), whereas primary HIV-1 variants are highly resistant to sCD4 neutralization. Previously, it was demonstrated that the domain from V1 to V3 of the HIV-1 gp120 molecule contains one of the major determinants of sCD4 neutralization sensitivity, and the same region has also been implicated as influencing syncytium-inducing (SI) capacity and T-cell-line tropism. To determine possible differences in sCD4 neutralization sensitivity between phenotypically distinct primary HIV-1 variants, a panel of non-syncytium-inducing (NSI) and SI HIV-1 variants was studied. Primary NSI and SI HIV-1 variants appeared to be equally resistant to sCD4 neutralization. Consistent with this observation, sCD4 did not induce gp120 shedding from either primary NSI or SI HIV-1 variants at 37 degrees C. Thus, it is not the potential of certain primary HIV-1 variants to infect T-cell lines but rather their adaptation to T-cell lines that is reflected in specific properties of the viral envelope which influence sCD4 neutralization sensitivity.

Antiviral Agents↗
PubMed1993

Relation of phenotype evolution of HIV-1 to envelope V2 configuration.

Biological variability of human immunodeficiency virus type-1 (HIV-1) is involved in the pathogenesis of acquired immunodeficiency syndrome (AIDS). Syncytium-inducing (SI) HIV-1 variants emerge in 50 percent of infected individuals during infection, preceding accelerated CD4+ T cell loss and rapid progression to AIDS. The V1 to V2 and V3 region of the viral envelope glycoprotein gp120 contained the major determinants of SI capacity. The configuration of a hypervariable locus in the V2 domain appeared to be predictive for non-SI to SI phenotype conversion. Early prediction of HIV-1 phenotype evolution may be useful for clinical monitoring and treatment of asymptomatic infection.

Acquired Immunodeficiency Syndrome↗
PubMed1993

HIV tropism.

Explore the source record for details and available documents.

CD4 Antigens↗
PubMed1993

Early replication steps but not cell type-specific signalling of the viral long terminal repeat determine HIV-1 monocytotropism.

The expression of human immunodeficiency virus type 1 (HIV-1) is enhanced after cell activation because of the interaction of cell-encoded nuclear factors that interact with binding sites in the long terminal repeats (LTRs). Here we studied the contribution of cell type-specific activation signals to differences in cytotropism of HIV-1 variants. Four closely related molecular HIV-1 clones with distinct biological phenotypes and different capacities to replicate in primary monocyte-derived macrophages (MDMs) or T cell lines were used. Sequence analysis of these LTRs revealed variation in functionally important regions. Adaptation of virus variants to particular host cells by differences in LTR responsiveness was analyzed. LTR-CAT constructs were transiently transfected in T cells that were stimulated with T cell-specific activation signals such as combinations of anti-CD3 or anti-CD28 MoAB or in primary monocytes that were stimulated with IL-3, IL-4, or GM-CSF. No differences in responsiveness to cell type-specific signals were demonstrated. To further elucidate the level of restriction in cell tropism, transfection of four full-length infectious molecular HIV-1 clones into 5-day cultured MDMs was performed. From all clones, competent virus could be rescued from MDMs by coculture with PHA-stimulated PBLs. However, following cell-free inoculation, proviral DNA could be detected by PCR analysis only in monocytes exposed to HIV-1 clones that previously were shown to establish productive infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1992

Differential tropism of clinical HIV-1 isolates for primary monocytes and promonocytic cell lines.

Previously we demonstrated a correlation between a nonsyncytium-inducing (NSI), non-T-cell line tropic phenotype of HIV-1 isolates and the capacity to replicate in primary monocyte-derived macrophages (MDM). Here we demonstrate that these NSI, monocytotropic HIV-1 isolates lack the capacity to replicate in two promonocytic cell-lines, HL60 and U937. In contrast, most syncytium-inducing (SI) HIV-1 isolates with tropism for T-cell lines and generally non-monocytotropic were able to establish a productive infection in promonocytic cell lines. Similar differences in tropism for monocytes and promonocytic cell lines were observed with infectious molecular clones. Our results indicate that virological studies on promonocytic cell lines do not necessarily pertain to the HIV-1 infection of monocytes in vivo.

Cell Line↗
PubMed1992

Genetic and functional analysis of a set of HIV-1 envelope genes obtained from biological clones with varying syncytium-inducing capacities.

To study HIV-1 envelope-mediated syncytium formation we have amplified, cloned, expressed, and sequenced individual envelope genes from a set of eight biological HIV-1 clones. These clones were obtained from two patients and display either a syncytium-inducing (SI) or nonsyncytium-inducing (NSI) phenotype. Upon expression through recombinant vaccinia virus, individual envelope gene products display heterogeneous syncytium-inducing capacities which reflect the phenotype of the parental biological HIV-1 clones in all cases. For the eight biological HIV-1 clones presented here, variation of the envelope gene alone is sufficient to explain the observed variable syncytium-inducing capacity of the respective parental viruses. In addition we determined the complete nucleotide sequence of these envelope genes. The predicted amino acid sequence revealed a considerable amount of variation located mainly in the previously denominated variable regions. In various regions of envelope genes obtained from the same patient, phenotype associated amino acid variation was found. This phenotype associated amino acid variation however, is not conserved between the two sets of envelope genes derived from different patients. Four envelope sequences derived from clones obtained from one patient showed phenotype-associated amino acid variation in the fusion domain. Sequencing of 12 additional fusion domains revealed that this same variation is found in four additional clones. However, a functional test performed on recombinant vaccinia expressing mutant envelope genes showed that this observed fusion domain variation does not contribute to the variation in syncytium-inducing capacity of the envelope gene product.

Amino Acid Sequence↗
PubMed1992

Phenotype-associated env gene variation among eight related human immunodeficiency virus type 1 clones: evidence for in vivo recombination and determinants of cytotropism outside the V3 domain.

The nucleotide sequences of the env genes of eight phenotypically heterogeneous human immunodeficiency virus type 1 (HIV-1) clones recovered from a single individual within a 3-week period were compared. In addition, the accessory gene sequences for four of these clones were obtained. Variation among most accessory genes was limited. In contrast, pronounced phenotype-associated sequence variation was observed in the env gene. At least three of these clones most likely resulted from genetic recombination events in vivo, indicating that this phenomenon may account for the emergence of proviruses with novel phenotypic properties. Within the env genes of the eight clones, four domains could be defined, the sequence of each of which clustered in two groups with high internal homology but 11 to 30% cluster variation. The extensive env gene variation among these eight clones could largely be explained by the unique manner in which the alleles of these four domains were combined in each clone. Experiments with chimeric proviruses demonstrated that the HIV-1 env gene determined the capacity to induce syncytia and tropism for T-cell lines. Amino acids previously shown to be involved in gp120-CD4 and gp120-gp41 interaction were completely conserved among these eight clones. The finding of identical V3 sequences in clones differing in tropism for primary monocytes and T-cell lines demonstrated the existence of determinants of tropism outside the env V3 region.

Amino Acid Sequence↗
PubMed1992

Phenotype-associated sequence variation in the third variable domain of the human immunodeficiency virus type 1 gp120 molecule.

The third variable (V3) domain has been implicated in determining the human immunodeficiency virus (HIV) phenotype, including fusion capacity and monocytotropism. In a large set of primary HIV type 1 (HIV-1) isolates, V3 sequence analysis revealed that fast-replicating, syncytium-inducing isolates contained V3 sequences with a significantly higher positive charge than those of slow-replicating, non-syncytium-inducing monocytotropic isolates. It appeared that these differences in charge could be attributed to highly variable amino acid residues located on either side of the V3 loop, midway between the cysteine residues and the central GPG motif. In non-syncytium-inducing monocytotropic isolates, these residues were negatively charged or uncharged, whereas in syncytium-inducing nonmonocytotropic isolates, either one or both were positively charged. The substitutions at these positions result in changes in the predicted secondary structure of the V3 loop. Our data suggest that two amino acid residues in the highly variable V3 domain are responsible for phenotype differences and point to conformational differences in V3 loops from phenotypically distinct HIV-1 isolates.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Phenotypic heterogeneity in a panel of infectious molecular human immunodeficiency virus type 1 clones derived from a single individual.

Previously, we and others have demonstrated a relation between the clinical course of human immunodeficiency virus type 1 (HIV-1) infection and biological properties of HIV-1 variants such as replication rate, syncytium-inducing (SI) capacity, and cytotropism. For the molecular analysis of the biological variability in these properties, we generated a panel of phenotypically distinct yet genetically highly homologous infectious molecular clones. These clones were derived from HIV-1 isolates, mostly recovered by direct clonal isolation, from a single individual in whom a transition from non-SI to SI isolates had been identified over time. Of 17 molecular clones tested, 8 were infectious. The clones exhibited differences in SI capacity and T-cell line tropism. Their phenotypes corresponded to those of their parental isolates, formally demonstrating that biological variability of HIV-1 isolates can be attributed to single molecular clones. With these clones we demonstrated that SI capacity and tropism for the H9 T-cell line, almost invariably coupled in primary HIV-1 isolates, are discernible properties. Also different requirements appeared to exist for H9 and Sup T1 cell line tropism. We obtained evidence that T-cell line tropism is not caused by differences in level of HIV-1 expression but most probably is restricted at the level of virus entry. Restriction mapping of four clones with divergent phenotypes revealed a high degree of nucleotide sequence homology (over 96.3%), indicating the usefulness of these clones for the tracking of genetic variability critical for differences in biological phenotype.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Analysis of the junctions between human immunodeficiency virus type 1 proviral DNA and human DNA.

Integrated retroviral DNA is flanked by short direct repeats of the target DNA. The length of these repeats is specific for the provirus that is integrated (H.E. Varmus, in J.A. Shapiro, ed., Mobile Genetic Elements, 1983). For the human immunodeficiency virus type I (HIV-1), the length of the direct repeats in the target DNA was shown to be 5 bp in one case (Muesing et al., Nature [London] 313:450-458, 1985) and 7 bp in another (Starcich et al., Science 227:538-540, 1985). One possible explanation for this discrepancy is that the direct repeats flanking HIV-1 proviruses are variable. To investigate this, we analyzed the junctions between HIV-1 proviral DNA and human DNA from nine individual clones. In each clone the provirus was flanked by a 5-bp direct repeat of human DNA. Analysis of the proviral clone previously described as being flanked by a 7-bp direct repeat of target DNA (Starcich et al., op. cit.) revealed that this clone was flanked by a 5-bp repeat instead. Therefore, we conclude that HIV-1 proviruses are flanked by 5-bp direct repeats of human DNA. The sequences of the 5-bp duplications from the different proviral clones do not have any apparent similarity to each other or to HIV-1 DNA.

Base Sequence↗
PubMed1989

Detection and subtyping of HIV-1 isolates with a panel of characterized monoclonal antibodies to HIV p24gag.

A panel of monoclonal antibodies (Mabs) was used to analyze the number and localization of B-cell epitopes on human immunodeficiency virus (HIV) p24gag and the variability of these epitopes in sequential HIV isolates and in isolates from different geographical origin. The specificity of these Mabs was demonstrated by immunoblotting and radioimmunoprecipitation assays. Cross-inhibition experiments indicated the presence of at least five different epitopes on p24. Analysis with p24 recombinant products revealed that three of the Mabs to p24 were directed to epitopes localized on the C-terminal part. Four other Mabs were directed to epitopes localized on the N-terminal half of the protein. Anti-p24 Mabs were used to develop HIV p24 antigen-capture assays. Application of these assays in HIV isolation resulted in more efficient recovery of HIV. Serotyping of HIV-1 isolates with five anti-p24 Mabs demonstrated that 55/65 isolates recovered from Dutch and Belgian individuals, but only 4/9 HIV-1 African isolates, were recognized by all five Mabs. Five of nine Central African HIV-1 isolates were not reactive with at least one of these Mabs. The variability of p24 appeared to be predominantly localized on the N-terminal part of the protein. Lack of expression of antigenic determinants on p24 was shown to be independent of culture conditions. Moreover, an infectious molecular clone was shown to have the same serotype as the corresponding HIV isolate. The serotype of sequential isolates obtained from 17 individuals over a 1 1/2- to 2 1/2-year period did not change, suggesting a limited in vivo p24 variation over time.

Acquired Immunodeficiency Syndrome↗