1,720,996 research outputs found
How does parvovirus B19 DNA achieve lifelong persistence in human cells?
No full textParvovirus B19 (B19V), a ssDNA virus in the family Parvoviridae, is characterized by several properties that convey
interest [1]. It is a pathogenic human virus with a selective tropism for erythroid progenitor cells (EPCs) in the bone
marrow. It can be responsible for a wide range of clinical manifestations, from the asymptomatic or mild to the
severe and in some cases life-threatening. It can establish a complex relationship with the immune system, whose
capacity of controlling infection varies widely and can be critical to the development of pathological processes. It is
characterized by a strict dependence on the cellular environment for its replication, so that the target cell types and
their differentiation stages condition the diverse outcomes of infection. As a general scheme, it is now accepted that
following a primary infection the virus can establish persistence in many tissues, probably lifelong. Questions then
arise about the characteristics of this long-term relationship, what form it can assume, whether the virus maintains
its full biological potential and what consequences, if any, this relationship can have on the host. At the state of our
research, more questions are open than knowledge established
Inhibition of Parvovirus B19 replication by Cidofovir in extendedly exposed erythroid progenitor cells
No full textHuman parvovirus B19 (B19V) commonly induces self-limiting infections but can also cause severe clinical manifestations in patients with underlying hematological disorders or with immune system deficits. Currently, therapeutic options for B19V entirely rely on symptomatic and supportive treatments since a specific antiviral therapy is not yet available. Recently a first step in the research for active compounds inhibiting B19V replication has allowed identifying the acyclic nucleoside phosphonate cidofovir (CDV). Herein, the effect of CDV against B19V replication was characterized in human erythroid progenitor cells (EPCs) cultured and infected following different experimental approaches to replicate in vitro the infection of an expanding erythroid cell population in the bone marrow. B19V replication was selectively inhibited both in infected EPCs extendedly exposed to CDV 500 μM (viral inhibition 82%) and in serially infected EPCs cultures with passages of the viral progeny, constantly under drug pressure (viral inhibition >99%). In addition, a potent inhibitory effect against B19V (>92%) was assessed in a short-term infection of EPCs treated with CDV 500 μM prior to viral infection. This enhanced anti-B19V activity of CDV could be ascribed both to the increased intracellular drug concentration achieved by extended exposure, and to a progressive reduction in efficiency of the replicative process within treated EPCs population
Inhibition of Parvovirus B19 replication by Cidofovir in extendedly exposed erythroid progenitor cells
No full textHuman parvovirus B19 (B19V) commonly induces self-limiting infections but can also cause severe clinical manifestations in patients with underlying hematological disorders or with immune system deficits. Currently, therapeutic options for B19V entirely rely on symptomatic and supportive treatments since a specific antiviral therapy is not yet available. Recently a first step in the research for active compounds inhibiting B19V replication has allowed identifying the acyclic nucleoside phosphonate cidofovir (CDV). Herein, the effect of CDV against B19V replication was characterized in human erythroid progenitor cells (EPCs) cultured and infected following different experimental approaches to replicate in vitro the infection of an expanding erythroid cell population in the bone marrow. B19V replication was selectively inhibited both in infected EPCs extendedly exposed to CDV 500 μM (viral inhibition 82%) and in serially infected EPCs cultures with passages of the viral progeny, constantly under drug pressure (viral inhibition >99%). In addition, a potent inhibitory effect against B19V (>92%) was assessed in a short-term infection of EPCs treated with CDV 500 μM prior to viral infection. This enhanced anti-B19V activity of CDV could be ascribed both to the increased intracellular drug concentration achieved by extended exposure, and to a progressive reduction in efficiency of the replicative process within treated EPCs population
Enhanced inhibition of parvovirus B19 replication by cidofovir in extendedly exposed erythroid progenitor cells
No full textHuman parvovirus B19 (B19V) commonly induces self-limiting infections but can also cause severe clinical manifestations in patients with underlying haematological disorders or with immune system deficits. Currently, therapeutic options for B19V entirely rely on symptomatic and supportive treatments since a specific antiviral therapy is not yet available. Recently a first step in the research for active compounds inhibiting B19V replication has allowed identifying the acyclic nucleoside phosphonate cidofovir (CDV). Herein, the effect of CDV against B19V replication was characterized in human erythroid progenitor cells (EPCs) cultured and infected following different experimental approaches to replicate in vitro the infection of an expanding erythroid cell population in the bone marrow. B19V replication was selectively inhibited both in infected EPCs extendedly exposed to CDV 500 μM (viral inhibition 82%) and in serially infected EPCs cultures with passage of the virus progeny, constantly under drug exposure (viral inhibition 99%). In addition, a potent inhibitory effect against B19V (viral inhibition 92%) was assessed in a short-term infection of EPCs treated with CDV 500 μM 1 day before viral infection. In the evaluated experimental conditions, the enhanced effect of CDV against B19V might be ascribed both to the increased intracellular drug concentration achieved by extended exposure, and to a progressive reduction in efficiency of the replicative process within treated EPCs population
Inhibitory effect of Cidofovir on Parvovirus B19 replication
No full textParvovirus B19 (B19V) is a human ssDNA virus responsible for a wide range of clinical manifestations, still lacking for a specific
antiviral therapy. The identification of compounds active against B19V may add therapeutic options to the treatment of B19V
infections. To this purpose, focus was raised to cidofovir (CDV), an acyclic nucleoside phosphonate broadly active against dsDNA
viruses.
Two model systems were used to assess the inhibitory effect of CDV on B19V replication: 1) the UT7/EpoS1 megakaryoblastoid cell
line, able to support B19V DNA replication; 2) the ex vivo expanded CD36+ erythroid progenitor cells (EPCs), a highly permissive
system for B19V replication and expression. EPCs were generated from peripheral blood, via culture in a medium containing
erythropoietic growth factors (EPO, SCF and Il-3), for up to 18 days. Expression of EPC differentiation markers ranged from a
minimum of 10% at 3-day to a 80% at 15-day culturing. Infection at different stages indicated that the EPC system was fully
permissive to B19V between days 6 and 15 of EPCs in vitro growth and differentiation.
Experiments were carried out at different multiplicity of infection (100 – 104 genomes/cell) and CDV concentrations (0.1 – 500 μM).
The effects of CDV were evaluated by its capacity to inhibit viral nucleic acid synthesis, as determined by means of q PCR assays
for quantification of viral nucleic acids. CDV showed a dose-dependent inhibiting activity on B19V replication within infected UT7/
EpoS1, allowing for the determination of EC50 and EC90 values (7.45–41.27 μM, and 84.73–360.7 μM, respectively). In EPCs, a
significant reduction on B19V DNA amounts was obtained only at 500 μM (68.2–92.8%). However, cell-culture supernatants from
B19V-infected, CDV-treated EPCs were used for serial infection of EPCs in the presence of CDV, leading to a progressive inhibition
of B19V replication compared to untreated controls.
With regard to the host cells, the drug did not interfere with the overall cellular DNA replication and metabolic activity. The effect of
CDV on B19V could be likely related to a specific inhibition on the viral replication process, indicating the possibility of developing
an antiviral strategy against a relevant human pathogenic virus
Parvovirus B19 infection in pregnancy - awareness and opportunities
No full textParvovirus B19 (B19V) is a human pathogenic virus associated with a wide range of clinical conditions. In pregnancy, B19V poses a potential hazard to the fetus as crossing the placental barrier and infecting erythroid progenitor cells in bone marrow and liver, it blocks fetal erythropoiesis leading to profound anemia, hydrops and/or fetal death. The virus is not regarded as a teratogen, however more scientific awareness is emerging on mechanisms and consequences of intrauterine infection and possible sequelae in the neonatal development. Reliable diagnostic procedures and fetal management strategies, including intrauterine transfusion, are established. In spite of being a recognized fetotropic agent possibly leading to fetal loss, testing for B19V is not routinely included in preconception or antenatal screenings, possibly delaying the management of B19V-complicated pregnancies. Continuous advances in B19V research will provide for better diagnostic methods and algorithms, as well as for the development of effective prophylactic interventions and novel therapeutic options
A Parvovirus B19 synthetic genome: sequence features and functional competence
No full textCentral to genetic studies for Parvovirus B19 (B19V) is the availability of genomic clones that may possess functional competence and ability to generate infectious virus. In our study, we established a new model genetic system for Parvovirus B19. A synthetic approach was followed, by design of a reference genome sequence, by generation of a corresponding artificial construct and its molecular cloning in a complete and functional form, and by setup of an efficient strategy to generate infectious virus, via transfection in UT7/EpoS1 cells and amplification in erythroid progenitor cells. The synthetic genome was able to generate virus with biological properties paralleling those of native virus, its infectious activity being dependent on the preservation of self-complementarity and sequence heterogeneity within the terminal regions. A virus of defined genome sequence, obtained from controlled cell culture conditions, can constitute a reference tool for investigation of the structural and functional characteristics of the virus
Hydroxyurea inhibits parvovirus B19 replication in erythroid progenitor cells
No full textParvovirus B19 (B19V) infection is restricted to erythroid progenitor cells (EPCs) of the human bone marrow, leading to transient arrest of erythropoiesis and severe complications mainly in subjects with underlying hematological disorders or with immune system deficits. Currently, there are no specific antiviral drugs for B19V treatment, but identification of compounds inhibiting B19V replication can be pursued by a drug repositioning strategy. In this frame, the present study investigates the activity of hydroxyurea (HU), the only disease-modifying therapy approved for sickle cell disease (SCD), towards B19V replication in the two relevant cellular systems, the UT7/EpoS1 cell line and EPCs. Results demonstrate that HU inhibits B19V replication with EC50 values of 96.2μM and 147.1μM in UT7/EpoS1 and EPCs, respectively, providing experimental evidence of the antiviral activity of HU towards B19V replication, and confirming the efficacy of a drug discovery process by drug repositioning strategy. The antiviral activity occurs in vitro at concentrations lower than those affecting cellular DNA replication and viability, and at levels measured in plasma samples of SCD patients undergoing HU therapy. HU might determine a dual beneficial effect on SCD patients, not only for the treatment of the disease but also towards a virus responsible for severe complications
Antiviral activity of brincidofovir on parvovirus B19
Full text linkParvovirus B19 (B19V), a single-stranded DNA virus in the family Parvoviridae, is a human pathogenic virus responsible for a wide range of clinical manifestations. Currently there is no approved antiviral therapy for parvovirus infection. The acyclic nucleoside phosphonate cidofovir (CDV) has been demonstrated to inhibit replication of B19V in vitro. The aim of the present study was to evaluate whether brincidofovir (BCV), a novel lipid conjugate of CDV, could also inhibit B19V replication. Experiments were carried out in erythroid progenitor cells (EPCs) and UT7/EpoS1 cells, infected with B19V and cultured in the presence of different concentrations of BCV and CDV for comparison. The dynamics of viral replication was evaluated by a qPCR-based assay and the extent of inhibition of viral replication exerted by the compounds determined, along with the effect of the compounds on cell viability and cell proliferation rates. Results confirmed that BCV showed significantly higher antiviral activity against B19V compared to CDV in both cell-based systems. For BCV, the calculated EC50 values were in the range 6.6-14.3 μM in EPCs and 0.22-0.63 μM in UT7/EpoS1 cells. In comparison, the EC50 values for CDV were >300 μM in EPCs and 16.1 μM in UT7/EpoS1 cells. Concurrently, the effects on cell viability were observed at a much higher concentration of BCV, with calculated CC50 values in the range 93.4-102.9 μM in EPCs and 59.9-66.8 μM in UT7/Epos1. The antiviral activity was observed specifically with the metabolically active stereoisomer of BCV suggesting that CDV-diphosphate, the metabolite of both BCV and CDV, was the active antiviral. Our results support a selective role for BCV in the inhibition of B19 viral replication
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