Detection Of Parvovirus B19 DNA Research Articles

Evaluation of a real-time PCR assay using the LightCycler system for detection of parvovirus B19 DNA.

We evaluated the artus RealArt Parvovirus B19 LC PCR reagent (artus biotech USA, San Francisco, Calif.) for real-time PCR detection of parvovirus B19 DNA by retesting 71 specimens previously submitted to our laboratory. The artus assay, which produces a quantitative result and provides an internal PCR control, appeared to be slightly more sensitive than our conventional qualitative PCR assay.

Quantitative real-time detection of parvovirus B19 DNA in plasma.

As of 2004, the European Pharmacopoeia demands that plasma pools for production of anti-D immunoglobulin should not contain more than 104 IU per mL of parvovirus B19 (B19V) DNA. Hence, before pooling, highly viremic donations have to be identified, and after pooling the level of B19V DNA must be determined. The performance of a new real-time B19V DNA PCR test (Roche, Mannheim, Germany) was studied, using a DNA extractor (NucliSens, bioMerieux, Boxtel, the Netherlands) for isolation of nucleic acid, and using a DNA quantification test (LightCycler apparatus, Roche, Mannheim, Germany) for amplification and detection. Dilutions of the international B19V DNA standard and reference preparations were tested to determine the precision, linear range, and accuracy of the assay and to calculate the factor for conversion of B19V DNA copies to IUs. The internal control signals, invalid test results, and the effect of cryo-poor plasma were studied as a measure for robustness. Routine performance was assessed by testing 164 manufacturing pools (not screened for B19V) and 1048 test pools of 480 donations each. The copies-to-IU conversion factor was calculated to be 3.34 (95% CI, 3.07-3.63). The assay appears linear between 10(3) and 10(7) IU per mL. Between 10(3) and 10(5) IU per mL, the test can discriminate samples differing a factor two in B19V DNA content. Overall, 0.78 percent of the test results were invalid. Of 127 B19V DNA negative control plasma samples, 7 were contaminated with low levels of B19V DNA. Of 164 nonscreened manufacturing plasma pools, 92 contained B19V DNA (56%); 13 contained more than 10(4) IU per mL. Of 503,040 donations, 29 contained more than 5 x 10(6) IU per mL B19V DNA (1:17,346). The B19V DNA quantification test (LightCycler, Roche ) is suitable for quantitative, routine, in-process measurement of B19V DNA levels in plasma pools, using the DNA extractor (NucliSens, bioMerieux) for nucleic acid isolation.

Diagnostic anténatal des infections à parvovirus B19

Parvovirus B19 infection of the pregnant women may sometimes induce hydrops fetalis or fetal loss. Around 50 % of pregnant women may contract this virus infection during pregnancy. The rate of infection vary between 1 and 13 % depending on the period of epidemics. Maternal infection is often asymptomatic but rash and arthralgia may occur. Vertical transmission rate is around 30 %, but only 1 to 10 % of the fetuses develop symptoms. The most specific pattern is the parvovirus B19 second-trimester hydrops fetalis which appears 3 to 10 weeks after maternal infection, and is due to fetal anemia consecutive to viral replication. The diagnosis of infection in hydrops fetalis is ascertained by the detection of parvovirus B19 DNA by PCR in the amniotic fluid or in the fetal serum. The treatment of hydrops fetalis is based on intra-uterine transfusions when fetal hemoglobin falls below 8g/dl. Systematic prenatal testing for specific immunity is not justified.

Detection of parvovirus B19 DNA by polymerase chain reaction in giant cell arteritis: a case-control study.

Detection of parvovirus B19 DNA by polymerase chain reaction in giant cell arteritis: a case-control study.

A quantitative, internally controlled real-time PCR Assay for the detection of parvovirus B19 DNA

Parvovirus B19 is an erythrovirus causing diverse clinical manifestations ranging from asymptomatic or mild, to more severe outcomes in, for example, immune-compromised patients. B19 is spread primarily via the respiratory route, but it can also be transmitted via blood and blood products. Viral loads in blood or plasma donations amount up to 10 11 genome equivalents/ml. Therefore, screening of plasma for fractionation for the presence of B19 and removal of highly loaded donations is a way to limit considerably the input of B19 into production pools and to improve further the safety of plasma products. An assay for the quantitative detection of B19 DNA, based on real-time PCR using ABI Prism SDS7700 (TaqMan) is described here. This assay allows precise quantitation of viral loads over 7 orders of magnitude. An exogenous internal control (internal quality marker) is included in each individual sample to prevent false negative results. A linearized plasmid is used as an internal quality marker that contains the identical sequence of the B19 target sequence but with an altered probe hybridization site. This allows co-amplification of B19 and internal quality marker and co-detection of FAM (6-carboxyfluorescein) or VIC labeled probes respectively. The assay is validated according to current guidelines (of the International Conference on Harmonization, Paul Ehrlich Institute, and the Council of Europe) and is optimized for high throughput screening.

Rapid detection of Parvovirus B19 DNA in children with sickle cell anemia by nested polymerase chain reaction ("Nested" PCR)

Rapid detection of Parvovirus B19 DNA in children with sickle cell anemia by nested polymerase chain reaction ("Nested" PCR)

Tyramide signal amplification of biotinylated probe in dot-blot hybridization assay for the detection of parvovirus B19 DNA in serum samples

Highly sensitive assay systems are necessary for large-scale virological screenings. We evaluated the use of tyramide signal amplification (TSA) for biotinylated probe in dot-blot hybridization assay to detect B19 DNA in serum samples. The probe was constructed by PCR and directly labeled with biotin during amplification reaction. The sensitivity of the dot-blot hybridization assay with TSA detection method was evaluated in comparison with a hybridization assay using the direct detection of biotinylated probe by streptavidin–biotin–alkaline phosphatase substrate. The TSA detection was able to detect 1 pg of B19 DNA and proved to be 10–50 times more sensitive than the hybridization assay with the direct detection of biotinylated probe. The analysis of 720 serum samples by TSA detection of biotinylated probe showed that the assay may be a valid diagnostic tool in routine testing of B19 DNA in serum samples.

Quantitative direct probe method for the detection of parvovirus B19.

Parvovirus B19 infection is associated with anemia and spontaneous abortions. While many qualitative assays are available, a few molecular-based quantitative methods have been described. This study reports the development and optimization of a quantitative direct-probe method for the detection of Parvovirus B19 DNA. Different concentrations of RNA probes were used to identify the optimal conditions for hybridizing to the target DNA. Detection of DNA was linear between concentrations of 2 ng/ml to 200 pg/ml. Because this method requires no enzymatic amplification, it is not susceptible to amplifier contamination or enzymatic inhibitors, and it can be applied to serum samples or paraffin-embedded tissue.

Standardization of a PCR-ELISA in serum samples: diagnosis of active parvovirus B19 infection.

To standardize a PCR assay for the detection of parvovirus B19 DNA in serum samples three different sample treatments were evaluated on the basis of the efficiency of recovery, reproducibility, convenience of sample handling, and presence of PCR inhibitors. Moreover, the presence of an internal standard competitor as the working reagent at one defined concentration in a competitive PCR-ELISA has been suggested as a valid tool to standardize and validate the assay. The results indicated that serum sample treatment by rapid heating fulfilled the criteria for a routine practice in the diagnostic laboratory. Titration experiments carried out to define the optimal amount of the internal standard competitor to use in PCR-ELISA showed that at 2 x10(2) competitor copies, any amplification interferences between target and competitor sequences were avoided. The internal standard competitor in a competitive PCR-ELISA allows the detection of false-negative results due to PCR inhibitors in the samples or large amounts of target DNA. Heating treatment and competitive PCR-ELISA for the detection of parvovirus B19 DNA were applied to the testing of 347 serum samples, which were submitted to the laboratory for B19 investigation. Of the 34 serum samples that were positive for B19 DNA, 15 were from adult patients and 19 from pediatric subjects. B19 infection was associated with haematological disorders, nonimmunological foetal hydrops, atypical rash, arthropathies, hepatic dysfunction, nonspecific symptoms, and congenital infections.

Human parvovirus B19: relevance in internal medicine

Infection by the human parvovirus B19 can lead to several clinical manifestations which are relevant in internal medicine. These include aplastic crisis in chronic haemolytic anaemias, exanthemathous disease and arthropathy, mainly in women, and chronic anaemia in the immunocompromised host. After initial replication, probably in the respiratory tract, the virus enters its target cells in the bone marrow, erythroid precursor cells, through its receptor, the blood group P antigen. Viral replication in these cells leads to an arrest in erythropoiesis, normally lasting approximately 1 week. In this stage, an aplastic crisis can be produced in all patients under ‘erythropoietic stress’. The viraemia disappears as specific antibodies to the virus become detectable in serum, which may give rise to a rash or arthralgia, symptoms that are probably immune-mediated. In immunologically normal individuals the infection is cleared by the humoral immune system within several weeks, whereafter detectable specific IgG confers lifelong immunity to reinfection. In patients with absent or dysfunctional humoral immunity to this virus, however, persistent infection can occur, which results in chronic suppression of erythropoiesis with chronic anaemia. Passive immunization, by means of normal immunoglobulin preparations has been reported to be effective in treating this condition. Diagnosis of parvovirus infection is usually possible by the detection of specific antibodies of IgM class in cases of recent infection. In patients with aplastic crisis and patients with chronic anaemia diagnosis rests upon the detection of parvovirus B19 DNA in serum by polymerase chain reaction. Parvovirus B19 is a ubiquitous virus. By the age of 15, about 50% of individuals have serologic evidence of a past infection, which may present as the common childhood disease erythema infectiosum. At the age of 70, seroprevalence reaches 80 to 100%. A vaccine against this virus is currently being developed.

Parvovirus B19 infection in thoracic organ transplant recipients.

Clinical manifestations of parvovirus B19 infection in immunocompromised patients are mostly reported as acute or chronic hematologic disorders. More recently, respiratory or renal involvement has been described. We started in 1994 a prospective study of parvovirus B19 infection in a group of lung (LTP) and heart-lung (HLTP) transplanted patients, including occasionally heart transplanted (HTP) patients. 62 patients (49 LTP, 11 HLTP, 2 HTP) were included in a serological survey and DNA detection by PCR was performed on each serum sample of the first 29 patients; later we performed it only when serology could suggest an acute episode, or when parvovirus infection could be suspected on clinical or biological observations. A total of 1655 sera were examined by serological tests and DNA detection was done in 500 samples. Specific IgM, seroconversion, significant increase of specific IgG levels, and/or parvovirus B19 DNA detection, were considered as markers of viral infection. We observed the presence of both markers of infection in 24 patients (39%), with an individual combination of positive antibody and PCR results. Acute or chronic anaemia, neutropenia were associated to these laboratory findings in 19 patients, but in five cases, an asymptomatic clinical infection suggested viral persistence. We report parvovirus associated acute or chronic anaemia and pancytopenia in a group of LTP, HLTP and HTP patients, as well as asymptomatic cases of infection. In the hypothesis of a parvoviral persistent or latent infection, current diagnosis methods may be unreliable to identify any other clinical manifestations.

Parvovirus B19 Infection in Pregnancy

Transplacental transmission of human parvovirus B19 (B19 virus) to the fetus is an important cause of intrauterine death, abortion, stillbirth, and nonimmune hydrops fetalis. Adverse outcome of pregnancy can occur after symptomatic and asymptomatic maternal infection. Only rare cases of congenital malformations and fetal disease in live-born infants have been associated with intrauterine B19 virus infection. Laboratory results obtained from paired maternal and fetal cord blood samples indicate that a reliable diagnosis of fetal B19 virus infection should be based on detection of parvovirus B19 DNA.

Detection of parvovirus B19 DNA in bone marrow cells by chemiluminescence in situ hybridization

A chemiluminescence in situ hybridization method was developed for the search of B19 parvovirus DNA in bone marrow cells, employing digoxigenin-labeled B19 DNA probes, immunoenzymatically detected with a highly sensitive 1,2-dioxetane phosphate as chemiluminescent substrate. The light emitted from the in situ-hybridized probe was analyzed and measured by a high-performance luminograph connected to an optical microscope and to a personal computer for the quantification of the photon fluxes from the single cells and for image analysis. The chemiluminescence in situ hybridization was applied to bone marrow cell smears of patients with aplastic crisis or hypoplastic anemia, who had been previously tested by in situ hybridization with colorimetric detection, dot blot hybridization, and nested PCR. The chemiluminescent assay provided an objective estimation of the data, proved specific, and showed an increased sensitivity in detecting B19 DNA compared with in situ hybridization with colorimetric detection.

Incidence of human parvovirus B19 DNA detection in blood donors

1000 serum samples from blood donors were tested for human parvovirus B19 (B19) DNA by a nested PCR assay: six samples were positive for B19 DNA. The frequency was 1/167 (0.6%), considerably higher than previous surveys (0.004-0.03%). Five of the six samples were also positive for anti-B19 IgM, indicating an acute phase of infection. It is recommended to screen for B19 DNA in blood products to prevent transfusion mediated viral infection for those susceptible such as immunocompromised patients and pregnant women.

In situ hybridisation and in situ polymerase chain reaction detection of parvovirus B19 DNA within cells

Modification of an in situ polymerase chain reaction (ISPCR) technique is described for the detection of B19 parvovirus infection. Specific amplification of B19 DNA inside fixed cells was followed by hybridisation with a digoxigenin-labelled probe and then visualised by immunochemical reaction. The assay had higher sensitivity compared to direct in situ hybridisation and still allowed cellular localisation and characterisation of infected cells. This assay can be used as a confirmatory method for PCR in tissues and will allow further identification of tissues permissive for B19 parvovirus infection.

Parvovirus B19 infection in HIV-1 infected patients with anemia.

Serum samples were analysed for IgM and IgG antibodies to parvovirus by ELISA and for parvovirus B19 DNA by polymerase chain reaction (PCR) in 69 HIV-1 infected Swedish patients with anemia and in 37 HIV-1 infected subjects without anemia. In 5/69 anemic patients, parvovirus B19 DNA was detected despite the lack of IgM antibody activity to the virus. The detection of parvovirus B19 DNA was significantly correlated to the degree of anemia in the anemic patients. In two patients who had a chronic anemia, a persistent parvovirus infection was detected by PCR, but not by serology, for 1 and 1.5 years, respectively. The results suggest that persistent parvovirus infection is a rare cause of anemia, but important to identify, since the infection is potentially treatable with intravenous immunoglobulin.

Detection of parvovirus B19 by dot-blot and polymerase chain reaction

Our studies compare detection of parvovirus B19 DNA by dot-blot hybridization and by the polymerase chain reaction (PCR). Compared to detection by dot-blot hybridization with a 32P-oligonucleotide probe, the sensitivity of PCR product detection by ethidium bromide fluorescence is not compromised when the size of the amplification target and number of cycles of amplification are properly selected. Our PCR assay simultaneously amplifies two targets in the B19 genome and yields a sensitivity 10 times greater than 32P-labelled oligonucleotide--dot-blot hybridization (dot-blot). In 126 serum samples from cases of suspected parvovirus B19 infection, viral DNA was detected by PCR in 17% (21/126), whereas dot-blot detected B19 DNA in 0.8% (1/126). Parvovirus B19-specific antibodies were detected in 69% (87/126) of the suspected clinical cases by immunoblot. Nineteen of the antibody-positive specimens were DNA positive of which three were IgM-positive/IgG-negative, 11 IgM-positive/IgG-positive and five IgM-negative/IgG-positive. The only dot-blot DNA positive sample was also PCR-DNA positive but was B19 IgM-negative/IgG-negative. Eighty-six B19 antibody-negative, clinically uninfected controls were also negative for B19 DNA by PCR and by dot-blot. These studies confirm the increased sensitivity of gene amplification by PCR for detection of B19 DNA and demonstrate that two targets in B19 DNA can be amplified simultaneously with resultant increased ease of interpretation. Finally, detection of the two B19-specific products by ethidium bromide fluorescence is documented.

Detection of parvovirus B19 DNA in fetal tissues by in situ hybridisation and polymerase chain reaction.

Attempts were made to detect human parvovirus B19-DNA by in situ hybridisation and the polymerase chain reaction in placental and fetal tissues from a case of intrauterine fetal death. In the in situ hybridisation experiments radioactive and non-radioactive (labelled with 2-acetyl-aminofluorene, AAF) DNA probes were used. B19-DNA was detectable in paraffin wax embedded fetal tissue from the liver, heart, lung, brain and thymus. The resolution with the AAF-labelled probes was higher than with the radiolabelled DNA. Parvovirus B19 DNA sequences were also detected in these tissues by an enzymatic in vitro amplification technique--the polymerase chain reaction. Amplification of a B19-DNA sequence before detection increases the rapidity and sensitivity of detection. The rapid, specific, and sensitive analysis of parvovirus B19 in normal and diseased tissues using these techniques may contribute considerably to determining the role of this virus as a risk factor in the outcome of pregnancy.