Biomedical subjects

B Wahren

Publications and source records attributed to B Wahren.

At least 73 records · Page 4Linked to original sources

PubMed1999

The use of peptides from glycoproteins G-2 and D-1 for detecting herpes simplex virus type 2 and type-common antibodies.

BACKGROUND: identification and discrimination of latent herpes simplex virus (HSV) infection relies on antibody identification. The inclusion of synthetic peptides with HSV glycoproteins provides means for stable and discriminatory assays for population studies. OBJECTIVE: to determine whether virus-specific synthetic peptides might identify HSV type 2 (HSV-2) antibodies in the presence of the cross-reactive and more common HSV type 1 (HSV-1) antibodies. STUDY DESIGN: the capacity of synthetic peptides as HSV antigens was analyzed in enzyme immunoassay (EIA) using well characterized human serum cohorts. The HSV peptide assays were evaluated in comparison with two commercial HSV-2 assays. RESULTS: a combination of two C-terminal HSV-1 glycoprotein D (gD-1) peptides detected type-common HSV immunoglobulin G (IgG) with high sensitivity (95%) and specificity (93%). Peptides derived from the C-terminus of HSV-2 glycoprotein G (gG-2) had a high HSV-2 type-specificity. Inclusion of both gD-1 and gG-2 peptides gave a sensitivity for human anti-HSV-2 IgG that was similar to that of assays including different amounts of native gG-2. With western blotting as a standard, the sensitivity of the peptide assay ranged between 86% for HSV-2 seropositive persons and 61% for HSV-2 seroconverters. Addition of a small amount of native gG-2 to the peptide assay tended to increase the specificity. CONCLUSION: HSV gG and gD peptides show promise as type-specific and type-common HSV antigens. These peptides are more stable and reproducibly prepared than native or recombinant glycoproteins and may be considered for inclusion in future HSV serodiagnostic assays.

Adolescent↗

PubMed1999

Seroprevalence of human herpes virus 8 in different Eritrean population groups.

BACKGROUND: Human herpesvirus 8 (HHV-8) is associated with Kaposi's sarcoma. In the US and Europe, HHV-8 is believed to be mainly sexually transmitted, but reports from some African countries suggest non-sexual transmission. OBJECTIVES: To find out more about HHV-8 seroprevalence and transmission in Eastern Africa. STUDY DESIGN: In this study, 411 serum samples from different population groups in Eritrea (children, pregnant women, female sex workers and members of the isolated Rashaida tribe) were examined for HHV-8 antibodies with an immunofluorescence assay detecting antibodies to latent and lytic HHV-8 antigens. RESULTS: Antibodies to HHV-8 latent antigen were found in 0-2% of Eritrean children, 5% of pregnant women, 8% of female sex workers and 26% of Rashaidas, respectively. No correlation was found between detectable HHV-8 antibodies and seropositivity to HIV or herpes simplex 2. CONCLUSIONS: These results suggest that HHV-8 infection is relatively common in Eritrea and that viral transmission occurs predominantly through non-sexual route in this region.

Adolescent↗

PubMed1999

Dendritic cell-derived nitric oxide is involved in IL-4-induced suppression of experimental allergic encephalomyelitis (EAE) in Lewis rats.

Cytokines play a crucial role in initiating and perpetuating EAE, an animal model of multiple sclerosis (MS). A low dose of IL-4, administered by the nasal route over 5 days (100 ng/rat per day) prior to immunization, improved clinical scores of EAE induced in Lewis rats with myelin basic protein (MBP) peptide 68-86 (MBP 68-86). We examined whether dendritic cells (DC) may have contributed to the amelioration of the disease process. These professional antigen-presenting cells (APC) not only activate T cells, but also tolerize T cells to antigens, thereby minimizing autoimmune reactions. We found that IL-4 administration enhanced proliferation of DC. In comparison with DC of PBS-treated rats, DC from IL-4-treated rats secreted high levels of interferon-gamma (IFN-gamma) and IL-10. Nitric oxide (NO) production by DC was also strongly augmented in IL-4-treated rats. In vitro studies showed that IL-4 stimulated DC expansion and that IFN-gamma enhanced NO production by DC. DC-derived NO promoted apoptosis of autoreactive T cells. These results indicate that nasal administration of IL-4 promotes activation of DC and induces production of IFN-gamma and IL-10 by DC. IL-10 suppresses antigen presentation by DC, while IFN-gamma induces NO production by DC which leads to apoptosis in autoreactive T cells. Such a DC-derived negative feedback loop might contribute to the clinical improvement observed in EAE.

Animals↗

PubMed1999

Suppression of chronic experimental autoimmune neuritis by nasally administered recombinant rat interleukin-6.

Experimental autoimmune neuritis (EAN) is a CD4+ T-cell-mediated demyelinating disease of the peripheral nervous system (PNS) and serves as experimental model for human immune-demyelinating neurophathies, especially the Guillain-Barré syndrome. In this study, we examined the effect of recombinant rat interleukin-6 (rrIL-6) on chronic EAN in Lewis rats induced by immunization with P2 peptide 57-81 and Freund's complete adjuvant (FCA). Nasal administration of rat rIL-6 (1 microg/rat/day) beginning in the initial phase of EAN as a therapeutic agent, decreased the severity and the duration of clinical EAN. Low-grade inflammation and suppression of regional demyelination within the sciatic nerves were seen in rrIL-6-treated rats. Hyporesponsiveness of lymph node T cells, down-regulation of serum tumour necrosis factor-alpha (TNF-alpha) and increased levels of P2-specific immunoglobulin G1 (IgG1) antibodies document that nasal administration of rrIL-6 was effective systemically. However, because of the non-specific nature of the treatment and multiple effects of IL-6, more experience and great caution are needed, before nasal administration of IL-6 can be considered as a treatment of human autoimmune demyelinating neurophathies.

Administration, Intranasal↗

PubMed1999

Immunogenetic properties of genes.

A most surprising finding is that when injected into animal tissue naked DNA is taken up and expressed by cells with great efficiency. The DNA is given as a plasmid that includes a promoter and an enhancer. When inoculated, the DNA is not stably integrated within the chromosomal DNA, but persists as extrachromosomal nuclear episomes. Both purified DNA and RNA have been shown to be expressed in somatic cells. It is now well established that injection of DNA by many routes may result in in vivo expression and that the proteins become immunogenic. DNA vaccines seem to induce efficient and complete immune responses. The immunizations produce long-term humoral and cellular responses, qualitatively similar to live attenuated vaccines but without the safety hazards of infectious agents. Recently, the first human DNA vaccinations were reported.

Antigen Presentation↗

PubMed1999

Properties and mechanism of action of a 17 amino acid, V3 loop-specific microantibody that binds to and neutralizes human immunodeficiency virus type 1 virions.

Only two virus-neutralizing peptide microantibodies (MicroAbs) have been described and little is known about their mode of action. This report concerns a 17 amino acid cyclized MicroAb, derived from the third complementarity-determining region of the heavy chain of MAb F58 (IgG1), that recognizes the same minimum epitope in the V3 loop of the gp120 envelope protein of human immunodeficiency virus type 1 (HIV-1) as the MAb. The MicroAb was able to bind to and neutralize free virus particles. It was up to 5-fold more efficient in mass terms than F58 IgG and its neutralization rate on a molar basis was only 32-fold lower. The mechanism of neutralization of the MicroAb was also investigated. A high level of neutralization (99%) occurred without any significant decrease in attachment of virus to target C8166 cells. Neutralized virus attached to CD4, the HIV-1 primary receptor. Fusion of virions to cells was partially inhibited by the MicroAb, whereas F58 IgG has been shown to inhibit fusion significantly. Thus, neutralization by the MicroAb appears to be mediated, at least in part, by inhibition of fusion. Control peptides, in which the tyrosine at position 5 or 6 was deleted or changed to phenylalanine, showed no antiviral activity, attesting to the specificity of interaction of the MicroAb with the virion. It therefore appears that the MicroAb acts like an immunoglobulin. The data also show that the MicroAb/MAb F58 epitope on the V3 loop is not involved in attachment of virus to CD4 but is required for subsequent events in early infection.

Amino Acid Sequence↗

PubMed1999

DNA-plasmids of HIV-1 induce systemic and mucosal immune responses.

DNA-based immunization has been shown to induce protective immunity against several microbial pathogens including HIV-1. Several routes of DNA vaccination have been exploited. However, the properties of the immune responses seem to differ with the different routes used for DNA delivery, ultimately affecting the outcome of experimental challenge. We measured the primary immune response following one vaccination. This report presents differences associated with three different DNA delivery routes: intramuscular injection, intranasal application, and gene-gun based immunization. Induction of systemic humoral immune responses was achieved most efficiently by either intranasal or gene-gun mediated immunization, followed by intramuscular injection. Mucosal IgA was reproducibly induced by intranasal instillation of the DNA, and found in lung washings, faeces, and vaginal washings. Cytotoxic T cells were not induced by a single immunization, but were observed after three immunizations using intramuscular injections.

AIDS Vaccines↗

PubMed1999

Long-term immunotherapy in HIV infection, combined with short-term antiretroviral treatment.

Forty asymptomatic HIV-infected individuals with CD4+ lymphocyte levels above 400x10(6)/l were immunized over 5 years with recombinant envelope glycoprotein gp160 (rgp160). After 5 years there was a trend towards more non-progressors in the immunized group as compared to the matched controls. Since immunizations could activate HIV, the first 6 immunizations were followed by 2 weeks of zidovudine or placebo, double-blind. The viral load did not change during the first 6 months and was not different from that of the matched controls after 5 years. The best effect on CD4+ lymphocyte development was seen in individuals with a high viral load randomized to rgp160+zidovudine and in individuals with a low viral load randomized to rgp160+placebo. We conclude that rgp160 is safe and results in temporarily improved CD4+ development. Concomitant antiviral treatment might be of benefit, especially in patients with a more advanced disease and can today be given with more effective combinations.

AIDS Vaccines↗

PubMed1998

[A review of the current research on prions. The evidence suggests the possibility of transmission of the mad cow disease to humans].

Further evidence of the transmissibility of bovine spongiform encephalopathy (BSE) across the species barrier from cow to man has been derived from epidemiological analysis and the characterisation of prion strains. Recent research has shown the persistence of prions after experimental transmission to resistant murine species, and subclinical persistence in cows. The accumulation of pathological prion proteins in tonsils and appendix has been demonstrated prior to clinical confirmation of the presence of the new variant of Creutzfeldt-Jakob disease. Current prion research is focused on the involvement of B lymphocytes as carriers, on the species barrier and cellular receptors, and on macromolecules involved in the conformational change from normal to pathological prion proteins.

Animals↗

PubMed1998

Rapid analysis of epitope-paratope interactions between HIV-1 and a 17-amino-acid neutralizing microantibody by electrospray ionization mass spectrometry.

Progress in therapeutic or prophylactic immune intervention in HIV-1 infections may only come about with a detailed understanding at the molecular/atomic level of how antibodies neutralize (inactivate) virus infectivity. Currently information on the molecular aspects of antibody-virus interaction comes predominantly from X-ray crystallography, a process that is dependent on the production of suitable crystals. NMR can also be valuable but is complex and time consuming, while mass spectrometry has been limited to matrix-assisted laser-desorption ionization (MALDI) analysis of peptides eluted from the cognate antibody. Here, we have used electrospray ionization mass spectrometry (ESI-MS) to detect directly the interactions of a novel 17-amino-acid microantibody (MicroAb) that has HIV-1-inhibitory activity, and peptides representing the V3 regions of primary HIV-1 strains isolated from Brazil (clade B) and Africa (clade A). The MicroAb is based on the third complementarity-determining region of the heavy chain (CDR-H3) of a murine monoclonal IGGI (F58) specific for the V3 loop of the gp120 envelope glycoprotein of HIV-1. ESI-MS proved to be rapid (taking < 3 h for the entire analysis), sensitive (analytes at 2 mmol/ml), and accurate (RMM estimation to 0.01-0.1%). With it, we showed that the MicroAb forms complexes with the V3 peptides, implying that its antiviral activity is mediated by binding directly to the virus particle. In addition, through controlled protease digestion of the V3 peptides, we concluded that the CDR-H3 MicroAb bound to RKXXXIGPGR, a region similar to the epitope of the whole IgG as determined by ELISA. We believe that the approach exemplified here will be applicable generally to the identification of groups involved in receptor-ligand interactions.

Amino Acid Sequence↗

PubMed1998

Treatment history and baseline viral load, but not viral tropism or CCR-5 genotype, influence prolonged antiviral efficacy of highly active antiretroviral treatment.

BACKGROUND: The efficacy of highly active antiretroviral treatment (HAART) in HIV-1 disease may vary between nucleoside-naive and experienced patients as well as between patients with different viral phenotypes and in different stages of disease. OBJECTIVE: To investigate variables of importance for successful long-term viral suppression by analysing virological, clinical and immunological characteristics at initiation of protease inhibitor treatment on suppression of HIV RNA over 1 year. DESIGN: An open, non-randomized, observational clinical study. SETTING: Venhälsan, Department of Dermatovenereology, Söder Hospital, Stockholm, Sweden. PATIENTS: A total of 147 unselected advanced patients with known HIV-1 infection for a mean of 7 years, of whom 37% had AIDS and who started treatment with a protease inhibitor during 1996. INTERVENTIONS: All patients received HAART with at least two nucleoside analogues in combination with either indinavir (81%) or ritonavir (19%). The majority (77%) had been previously treated with nucleoside analogues for a mean of 39 months. MEASUREMENTS: CD4+ lymphocyte count, plasma HIV-1 RNA, viral phenotype and HIV-1 coreceptor CCR-5 genotype at baseline. Viral load and CD4+ lymphocyte count were determined every 3 months. RESULTS: Patients were analysed on an intention-to-treat basis. The mean CD4+ lymphocyte count at baseline was 170 x 10(6)/l and the median viral load was 68 600 copies/ml. Heterozygosity for the delta32 deletion of the CCR-5 gene (delta32/wt) was found in 27%. MT-2 positive virus (syncytium-inducing) was isolated in 46%. Logistic regression revealed that nucleoside analogue experience and baseline log10 HIV-1 RNA were the only factors independently related to plasma HIV-1 RNA levels below 500 copies/ml after 1 year of treatment, which was found in 69%. CONCLUSION: The virological outcome after 1 year of HAART was strongly correlated to prior treatment history and baseline viral load, whereas CD4+ lymphocyte count, CCR-5 genotype and viral biological phenotype had less influence. The long-term antiviral efficacy of HAART was lowest in individuals with previous nucleoside analogue treatment and a high baseline viral load. In these individuals an even more aggressive treatment should be considered.

Adult↗

PubMed1998

Immune responses but no protection against SHIV by gene-gun delivery of HIV-1 DNA followed by recombinant subunit protein boosts.

The efficacy of combining immunization with human immunodeficiency vitus type 1 (HIV-1) DNA and HIV-1 recombinant proteins to obtain protection from chimeric simian/human immunodeficiency virus (SHIV) was determined. Four cynomolgus monkeys received four gene-gun immunizations intraepidermally of plasmid DNA encoding HIV-1lai env (gp160), gag, tat, nef, and rev proteins. Ten micrograms of DNA was used per immunization. The animals were boosted twice intramuscularly with 50 microgram of HIV-1lai Env (MicroGeneSys), Gag, Tat, Nef, and Rev recombinant proteins mixed in Ribi adjuvant. The antibody responses were amplified following the administration of the recombinant subunit boosts. One month after the final subunit immunization, the vaccinated animals together with four control animals were challenged intravenously with 10 monkey infectious doses of SHIV that expresses the env, tat and rev genes of HIV-1 and gag and nef from SIV. However, only low titers of neutralizing antibodies were present at the day of challenge. The consecutive HIV-1 DNA and recombinant protein immunizations induced B- and T-cell responses but not protection against SHIV replication nor reduction of the viral load.

AIDS Vaccines↗

PubMed1998

Linomide suppresses chronic-relapsing experimental autoimmune encephalomyelitis in DA rats.

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on chronic progressive and/or relapsing experimental autoimmune encephalomyelitis (PR-EAE), a CD4+ T cell mediated animal model of multiple sclerosis (MS). PR-EAE induced in DA rats by inoculation with homogenized guinea pig spinal cord and Freund's complete adjuvant, was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical PR-EAE, reduced severity and relapse of clinical PR-EAE, and shortened clinical PR-EAE. These clinical effects were associated with the down-modulation of CNS antigen-induced T cell responses and production of proinflammatory cytokines (IFN-gamma and TNF-alpha) as well as with upregulation of IL-4 (except in spleen MNC), IL-10 and TGF-beta in both spleen MNC and the spinal cord. These effects indicate that Linomide can suppress PR-EAE and may mediate its suppressive effects by regulation of cytokines.

Adjuvants, Immunologic↗

PubMed1998

Treatment with P2 protein peptide 57-81 by nasal route is effective in Lewis rat experimental autoimmune neuritis.

Experimental autoimmune neuritis (EAN) is a CD4+ T cell-mediated autoimmune disorder of the peripheral nervous system (PNS) that can be actively induced in susceptible animal species and strains by active immunization with PNS myelin + Freund's complete adjuvant (FCA). EAN represents an animal model for studying the immunopathogenesis and treatment of Guillain-Barré syndrome (GBS), which is a major inflammatory demyelinating disease of the PNS in humans. Here, we report that treatment by nasal administration of the neuritogenic peptide 57-81 of the PNS myelin component, P2 protein, dose-dependently suppressed EAN severity and shortened clinical EAN. Clinical EAN relapse induced by rechallenge with BPM + FCA was also prevented in EAN rats receiving high dose P2 peptide. P2 peptide induced suppression of EAN was associated with PNS antigen specific T cell hyporesponsiveness reflected by lymphocyte proliferation, numbers of PNS antigen-reactive IFN-gamma secreting and IFN-gamma mRNA expressing lymph node cells, but elevated levels of PNS antigen reactive TGF-beta mRNA secreting cells. Reduced CD4+ T cell and macrophage infiltrations within the PNS were also observed. Based on these observations, nasal autoantigen administration should be further evaluated, considering its possible future use in GBS.

Administration, Intranasal↗

PubMed1998

Linomide suppresses acute experimental autoimmune encephalomyelitis in Lewis rats by counter-acting the imbalance of pro-inflammatory versus anti-inflammatory cytokines.

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on experimental autoimmune encephalomyelitis (EAE), a CD4+ T cell-mediated animal model of multiple sclerosis (MS). EAE induced in Lewis rats by inoculation with homogenized guinea pig spinal cord and Freund's complete adjuvant was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical EAE, and reduced severity of EAE symptoms. These clinical effects were associated with dose-dependent down-modulation of myelin antigens-induced T cell responses and by suppression of the proinflammatory cytokines IFN-gamma and TNF-alpha, and upregulation IL-4, IL-10 and TGF-beta as evaluated by in situ hybridization for mRNA expression in spleen mononuclear cells and spinal cord sections. These findings suggest that Linomide could be useful in certain T cell dependent autoimmune diseases.

Acute Disease↗

PubMed1998

MT-2 tropism and CCR-5 genotype strongly influence disease progression in HIV-1-infected individuals.

BACKGROUND: The beta-chemokine receptor CCR-5 is the coreceptor for cellular entry by non-syncytium-inducing (NSI) HIV-1 strains that dominate early in infection. A 32 base-pair deletion (delta32) in the CCR-5 gene renders this coreceptor non-functional. Heterozygosity for this deletion [delta32/wild-type (wt)] is associated with slow disease progression. The purpose of this study was to document the combined impact on HIV-1 disease progression of the CCR-5 genotype and the biological phenotype of HIV-1. METHODS: In a cross-sectional study of 258 HIV-1-infected Swedish individuals, the CCR-5 genotype (wt/wt or delta32/wt) was determined by polymerase chain reaction and the biological phenotype [NSI or syncytium-inducing (SI)] of virus isolates was determined in the MT-2 cell assay. Clinical status, HIV-1 RNA levels in plasma, CD4+ lymphocyte counts, and rate of CD4+ lymphocyte decline, based on retrospective analysis of CD4+ lymphocyte counts, were also recorded. None of the individuals were treated with protease inhibitors. RESULTS: The prevalence of the delta32/wt genotype was 23%. Subjects with the delta32/wt CCR-5 genotype more often carried SI virus than subjects with the wt/wt genotype (49 versus 35%; P=0.067), but there were no differences between the two groups in prevalence of AIDS, viral load, CD4+ lymphocyte count or CD4+ slope. NSI virus isolates were found in 159 (62%) out of 258 individuals. Individuals with NSI had lower prevalence of AIDS (39 versus 19%; P < 0.01), higher CD4+ lymphocyte counts (289+/-188 x 10(6)/l versus 153+/-162 x 10(6)/l; P=0.001), lower viral loads (median, 4.45 log10 versus 4.91 log10 copies/ml; P < 0.01) and a lower prevalence of the delta32/wt genotype (19 versus 29%; P=0.067) compared with individuals with SI virus. When the material was further subdivided, subjects with the delta32/wt genotype and SI virus had the highest prevalence of AIDS (P < 0.001), lowest CD4+ lymphocyte count (P=0.0001) and highest viral load (P=0.023) whereas the opposite was true for subjects with the delta32/wt genotype and NSI virus. A significantly higher proportion of subjects with NSI virus with delta32/wt and wt/wt CCR-5 genotype had been immunized with recombinant gp160. CONCLUSION: In summary, the delta32/wt CCR-5 genotype has a protective effect against HIV-1 disease progression that appears to be limited to individuals carrying HIV-1 variants with NSI phenotype. Immunization with recombinant gp160 tended to reduce the frequency of SI phenotypes.

AIDS Vaccines↗

PubMed1998

Cellular cytotoxic response induced by DNA vaccination in HIV-1-infected patients.

BACKGROUND: DNA vaccination is known to generate immune responses against HIV-1 in animal models. We aimed to assess the efficacy of DNA vaccination in induction of immune responses in HIV-1-infected human beings. METHODS: Nine symptom-free HIV-1-infected patients were immunised with DNA constructs encoding the nef, rev, or tat regulatory genes of HIV-1. The patients were selected for having no or low antibody reactivities to these antigens. HIV-1-specific cytotoxic T-lymphocytes (CTLs), precursor frequencies, and antigen-specific proliferative responses were measured before, during, and after three immunisations over 6 months. FINDINGS: Cellular immune reactivities against the HIV-1 regulatory proteins were absent or low before DNA immunisation. DNA vaccination induced detectable memory cells in all patients and specific cytotoxicity in eight patients. CTLs were MHC-class-I restricted and mainly of CD8+ origin. In three patients the cellular activity was transient, decreasing after an initial response. INTERPRETATION: DNA immunisation with HIV-1 genes can induce specific cellular responses in human beings with no apparent side-effects. It is theoretically possible that HIV-1-specific cytotoxic responses to regulatory proteins could lead to infected cells being eliminated before they have released new viral particles. However, it is possible that the patients we selected responded less than would non-selected or non-infected individuals. The small number of patients presented here does not allow generalisation of our findings.

AIDS Vaccines↗

PubMed1998

Synthetic peptides fail to induce nasal tolerance to experimental autoimmune myasthenia gravis.

Nasal administration of Torpedo acetylcholine receptor (AChR) to Lewis rats prior to induction of experimental autoimmune myasthenia gravis (EAMG) is highly efficient in prevention of clinical weakness, and suppression of AChR-specific T and B cell responses. To identify possible antigenic determinants within the receptor which can modulate EAMG and anti-AChR response, we evaluated the effects of nasal administration of alpha 61-76, alpha 100-116, alpha 146-162, delta 354-367, and alpha 261-277 of Torpedo AChR at different doses on the tolerance induction against EAMG irrespective if given at lower, the same or higher doses than whole Torpedo AChR protein, that was confirmed to be highly efficient as tolerogen to EAMG. None of these peptides, neither administrated alone nor in combination, induced tolerance to EAMG. Peptide administration did not affect the levels or affinities of anti-AChR antibodies when compared with non-tolerized control EAMG rats, while administration of whole AChR protein affected both variables. The results may indicate that the T and B cell heterogeneity of AChR epitopes makes it difficult to induce tolerance using synthetic peptide.

Animals↗