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Dive into the research topics where A. de Ronde is active.

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Featured researches published by A. de Ronde.


Journal of General Virology | 1993

Host cell membrane proteins on human immunodeficiency virus type 1 after in vitro infection of H9 cells and blood mononuclear cells. An immuno-electron microscopic study.

Timo Meerloo; M. A. Sheikh; A. C. Bloem; A. de Ronde; Martin Schutten; C. A. C. Van Els; P. J. M. Roholl; Piet Joling; Jaap Goudsmit; H.-J. Schuurman

Human immunodeficiency virus type 1 (HIV-1)-infected H9 and blood mononuclear cells (MNCs) were studied by immunogold electron microscopy for the presence of HIV-1 gag p24 protein, env gp41 and gp120 proteins, and host cell molecules CD4, CD11a, CD25, CD54, CD63, HLA class I and HLA-DR. Uninfected H9 cells and MNC membranes labelled for CD4, HLA class I and class II, and, at low density, CD11a and CD54; lysosomal structures in the cytoplasm labelled for CD63. The infected cell surface showed immunolabelling for HIV-1 proteins, as did budding particle-like structures. Immunogold labelling of the cell membrane for CD4 was almost non-existent. The level of immunolabelling for CD11a and CD54 on infected cells was greater than that on uninfected cells; this is presumably related to a state of activation during virus synthesis. Budding particle-like structures and free virions in the intercellular space were immunogold-labelled for all host cell markers investigated. This was confirmed by double immunogold labelling using combinations of HIV-1 gag p24 labelling and labelling for the respective host cell molecule. We conclude that virions generated in HIV-1-infected cells concentrate host-derived molecules on their envelope. Also molecules with a prime function in cellular adhesion concentrate on the virion.


Hiv Medicine | 2004

Greater and more rapid depletion of mitochondrial DNA in blood of patients treated with dual (zidovudine+didanosine or zidovudine+zalcitabine) vs. single (zidovudine) nucleoside reverse transcriptase inhibitors.

Peter Reiss; Miriam Casula; A. de Ronde; G. J. Weverling; Jaap Goudsmit; J. M. A. Lange

Most toxicities associated with nucleoside analogue reverse transcriptase inhibitors (NRTIs) are thought to result from mitochondrial toxicity. These toxicities include peripheral neuropathy, pancreatitis, lactic acidosis, and peripheral lipoatrophy. Unfortunately, there are no validated laboratory markers for clinically assessing, let alone predicting, the onset of mitochondrial toxicity associated with NRTI therapy.


Journal of General Virology | 1992

Analysis of human immunodeficiency virus type 1 LTR-LTR junctions in peripheral blood mononuclear cells of infected individuals.

Suzanne Jurriaans; A. de Ronde; John T. Dekker; Jaap Goudsmit; Marion Cornelissen

Circularized DNA species containing two long terminal repeat circle junctions were analysed in peripheral blood mononuclear cells of human immunodeficiency virus type 1 (HIV-1)-infected individuals. The circle junction fragments found could be classified into four groups: fragments containing a normal circle junction, fragments with deletions at the circle junction, fragments containing the primer binding site inserted at the circle junction, and fragments containing insertions at the circle junction derived from other regions of the HIV-1 genome.


Virology | 1989

The SV40 small t antigen is essential for the morphological transformation of human fibroblasts

A. de Ronde; Cees Sol; A. van Strien; J. ter Schegget; J. van der Noordaa

The morphological transformation of human fibroblasts as measured in an assay for dense focus formation required, besides the SV40 large T antigen, an intact SV40 small t antigen. Using a G418-resistant colony formation assay it also was found that expression of the SV40 large T antigen only is not sufficient for the morphological transformation of human fibroblasts. Therefore it is concluded that the SV40 small t antigen is essential for the morphological transformation of human fibroblasts.


AIDS | 2001

Carrier rate of zidovudine-resistant HIV-1: the impact of failing therapy on transmission of resistant strains.

Jaap Goudsmit; G. J. Weverling; L. van der Hoek; A. de Ronde; Frank Miedema; R. A. Coutinho; J. M. A. Lange; Maarten C. Boerlijst

ObjectiveBecause maintenance of treatment success in HIV-1 infection requires viruses to remain therapy sensitive in drug-naive seropositive persons, we looked at the primary infections caused by drug-resistant HIV-1 over time. Furthermore, to study the coverage rate of therapy and therapy failure in relation to the transmission of resistant viruses a mathematical model was developed. DesignThe reverse transcriptase and protease genes of viruses were analysed in newly infected people in the period 1990–1998 in the Amsterdam Cohort Study on HIV infection and AIDS in homosexual men. MethodsThe mathematical model was based on the coverage of drug regimens selecting zidovudine (ZDV) resistance, the lag time in which resistance is gained or lost, the death rate of people infected with resistant virus, and the replacement of resistance-selecting regimens by more potent treatments that substantially reduce viral load and mortality. ResultsOf 43 individuals with a primary HIV-infection, three (7%) harboured ZDV-resistant viruses. The first of the ZDV-resistant strains was transmitted in 1995, the last two in 1996. The build-up of ZDV resistance was described by the mathematical model indicating that the equilibrium level of resistance due to treatment depends only on the treatment rate and the outflow rate of patients with resistance virus. ConclusionsOur model indicates that the frequency of viral resistance in a population is determined largely by the number of individuals on insufficient or failing therapy and is influenced only modestly by secondary transmission of ZDV-resistant strains.


Veterinary Immunology and Immunopathology | 1995

Vaccination against feline immunodeficiency virus using fixed infected cells

Ernst J. Verschoor; A.L.W. van Vliet; Herman Egberink; W. Hesselink; W.E. van Alphen; I. Joosten; C.J.P. Boog; Marian C. Horzinek; A. de Ronde

Crandell feline kidney cells and feline thymocytes, either feline immunodeficiency virus (FIV) infected or uninfected, were fixed with paraformaldehyde and used to vaccinate cats. The cells were mixed with a 30:70 water/mineral oil emulsion containing 250 micrograms ml-1 N-acetyl-D-glucosaminyl-beta-(1-4)-N-acetyl-muramyl-L-alanyl-D-isoglutam ine. Eighteen specific pathogen-free cats were vaccinated three times with 3-week intervals and challenged 21 days after the final boost with a low dose of the homologous FIV-UT113 strain. Eight out of ten cats that had received FIV-infected cell vaccines developed significant anti-FIV antibody titres to the envelope and core antigens. Neutralizing antibodies were detectable at the moment of challenge in the sera of these animals. Within 5 weeks after challenge 15 out of 18 cats became viraemic. Three animals, two that had been vaccinated with FIV-infected thymocytes and did not develop antibody, and one that had received an uninfected thymocyte preparation, remained uninfected for 6 months. Upon rechallenge of the three animals, two again resisted infection; these cats had been immunized with the infected and the uninfected thymocyte preparations, respectively.


Journal of General Virology | 1997

Salmonella typhimurium aroA recombinants and immune-stimulating complexes as vaccine candidates for feline immunodeficiency virus.

Edwin J. Tijhaar; Willem Huisman; Robin C. Huisman; Kees H.J. Siebelink; Jos A. Karlas; A. de Ronde; R. van Herwijnen; Frits R. Mooi; Albert D. M. E. Osterhaus

Two experimental feline immunodeficiency virus (FIV) vaccines were tested, either alone or in combination, in four groups of cats (A-D). One vaccine (SL3261-FIV) was composed of live attenuated Salmonella typhimurium aroA (SL3261) strains expressing the capsid (Gag) and part of the envelope (Env) proteins of FIV. The other was composed of FIV Gag and Env proteins incorporated into immune-stimulating complexes (iscom-FIV). Cats of group A were immunized four times with SL3261-FIV. Cats of group B were immunized twice with SL3261-FIV and then twice with iscom-FIV. Cats of group C were immunized twice with SL3261 expressing the B subunit of cholera toxin (SL3261-CtxB) and then twice with iscom-FIV. Cats of group D, which served as negative controls, were immunized twice with SL3261-CtxB and then twice with iscom into which the Gag and Env proteins of simian immunodeficiency virus (SIV) had been incorporated (iscom-SIV). Two weeks after the last immunization, all cats were challenged with FIV. At this time, cats immunized with iscom-FIV (groups B and C) showed strong plasma antibody responses to Gag and Env, whilst these responses were weak or undetectable in the cats immunized four times with SL3261-FIV (group A). Seven weeks after FIV challenge, Env-specific antibody responses had increased considerably in cats of all groups except group A. The mean virus loads in the cats of this group proved to be lower than those of the other groups at all time points, indicating partial protection.


Journal of General Virology | 1994

Monoclonal antibodies to immunodominant and neutralizing domains of the envelope surface protein of feline immunodeficiency virus

Marian C. Horzinek; Herman Egberink; Lian Keldermans; N M P Schuurman; Jeanette G. Stam; W. Hesselink; Arno L. W. van Vliet; Ernst J. Verschoor; A. de Ronde

Hybridomas secreting monoclonal antibodies (MAbs) specific for the surface protein (SU) of feline immunodeficiency virus were generated. Four MAbs were obtained which could be assigned to two groups based on their neutralization and competition behaviour. Using SU protein fragments expressed in Escherichia coli the antigenic site recognized by one of the MAbs (2H11) could be mapped to the c terminus. The neutralizing MAb 1E1 did not bind to any of the SU protein fragments and was directed to a conformational epitope. Binding of the MAb 1E1 to native SU protein could be blocked with a rabbit serum raised against the SU3 fragment (amino acids 361 to 445). These data indicate that at least part of the epitope is located on this SU3 domain. In competition experiments most sera of naturally infected cats were able to inhibit binding of the MAbs. This shows the conserved and immunodominant nature of the epitopes involved.


Intervirology | 1987

The early enhancer-promoter of BKV and host range for transformation

A. de Ronde; Marcy E. MacDonald; Cees Sol; J. ter Schegget; E. Wouters; A. van Strien; J. van der Noordaa

The early genes of the human papovavirus BKV and simian virus 40 (SV40) show a different host range for transformation. The early region of SV40 efficiently transforms human fibroblast cells, whereas the early region of BKV does not. Interchanging noncoding enhancer-promoter sequences around the origin of replication between BKV and SV40 showed that the early enhancer-promoter sequences of BKV and SV40 could substitute for each other, as far as the induction of expression of tumor antigens and morphological transformation is concerned; the efficiency of transformation was influenced by the enhancer-promoter sequences, and the difference in host range for transformation between BKV and SV40 was determined by the early gene products rather than by the enhancer-promoter sequences.


Intervirology | 1987

Two domains within the early coding region of SV40 involved in the transformation of human fibroblasts.

A. de Ronde; Cees Sol; Marcy E. MacDonald; M. Koot; J. ter Schegget; A. van Strien; E. Wouters; J. van der Noordaa

The early gene products of simian virus 40 (SV40) transform human fibroblasts, whereas those of the human papovavirus BK (BKV) do not. The early gene products of both SV40 and BKV transform baby rat kidney cells. SV40-BKV chimerics were constructed which were able to transform baby rat kidney cells. Using the SV40-BKV chimerics, two domains within the SV40 large T protein were identified which are involved in the transformation of human fibroblasts.

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Cees Sol

University of Amsterdam

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Ernst J. Verschoor

Biomedical Primate Research Centre

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E. Wouters

University of Amsterdam

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