Advances in the Development of Antiviral Strategies against Parvovirus B19

Parvovirus B19 (B19V) is a human pathogenic virus, responsible for an ample range of clinical manifestations. Infections are usually mild, self-limiting, and controlled by the development of a specific immune response, but in many cases clinical situations can be more complex and require therapy. Presently available treatments are only supportive, symptomatic, or unspecific, such as administration of intravenous immunoglobulins, and often of limited efficacy. The development of antiviral strategies against B19V should be considered of highest relevance for increasing the available options for more specific and effective therapeutic treatments. This field of research has been explored in recent years, registering some achievements as well as interesting future perspectives. In addition to immunoglobulins, some compounds have been shown to possess inhibitory activity against B19V. Hydroxyurea is an antiproliferative drug used in the treatment of sickle-cell disease that also possesses inhibitory activity against B19V. The nucleotide analogues Cidofovir and its lipid conjugate Brincidofovir are broad-range antivirals mostly active against dsDNA viruses, which showed an antiviral activity also against B19V. Newly synthesized coumarin derivatives offer possibilities for the development of molecules with antiviral activity. Identification of some flavonoid molecules, with direct inhibitory activity against the viral non-structural (NS) protein, indicates a possible line of development for direct antiviral agents. Continuing research in the field, leading to better knowledge of the viral lifecycle and a precise understanding of virus–cell interactions, will offer novel opportunities for developing more efficient, targeted antiviral agents, which can be translated into available therapeutic options.

Saccharomyces cerevisiae-derived virus-like particle parvovirus B19 vaccine elicits binding and neutralizing antibodies in a mouse model for sickle cell disease

Parvovirus B19 infections are typically mild in healthy individuals, but can be life threatening in individuals with sickle cell disease (SCD). A Saccharomyces cerevisiae-derived B19 VLP vaccine, now in pre-clinical development, is immunogenic in wild type mice when administered with the adjuvant MF59. Because SCD alters the immune response, we evaluated the efficacy of this vaccine in a mouse model for SCD. Vaccinated mice with SCD demonstrated similar binding and neutralizing antibody responses to those of heterozygous littermate controls following a prime-boost-boost regimen. Due to the lack of a mouse parvovirus B19 challenge model, we employed a natural mouse pathogen, Sendai virus, to evaluate SCD respiratory tract responses to infection. Normal mucosal and systemic antibody responses were observed in these mice. Results demonstrate that mice with SCD can respond to a VLP vaccine and to a respiratory virus challenge, encouraging rapid development of the B19 vaccine for patients with SCD.

Safety and immunogenicity of a candidate parvovirus B19 vaccine

Parvovirus B19 is an important human pathogen causing erythema infectiosum, transient aplastic crisis in individuals with underlying hemolytic disorders and hydropsfetalis. We therefore evaluated a parvovirus B19 virus like particle (VLP) vaccine. The safety and immunogenicity of a 25 μg dose of parvovirus B19 recombinant capsid; 2.5 and 25 μg doses of the recombinant capsid given with MF59; and saline placebo were assessed in healthy adults. Because of 3 unexplained cutaneous events the study was halted after enrollment of 43 subjects and before any subject received their third scheduled dose. The rashes developed 5-9 days after the first or second injection and were seen in one placebo recipient (without an injection site lesion) and two vaccine recipients (with injection site reactions). No clear cause was established. Other safety evaluations revealed mostly injection site reactions that were mild to moderate with an increase in pain in subjects receiving vaccine and MF59. After dose 2 the majority of vaccine recipients developed ELISA and neutralizing antibody to parvovirus B19. Given the possible severe consequences of parvovirus B19 infection, further development of a safe and effective vaccine continues to be important.

[Childhood diseases with exanthema]

- Due to high vaccination coverage, measles and rubella (German measles) are now rarely seen in the Netherlands, which makes recognition of these diseases difficult. - Measles can also occur in people who have been immunized, as a result of vaccination failure. - Swift recognition of measles and rubella is necessary in order to manage them adequately and to prevent spreading of the disease. - Measles, rubella, and erythema infectiosum ('fifth disease') may result in complications during pregnancy. - Measles, rubella, scarlet fever, erythema infectiosum, and roseola ('sixth disease') can be difficult to differentiate. - In the Netherlands, diagnosis of a patient with measles or rubella, or of more than 1 patient with erythema infectiosum within one institution, must be reported to the local health authority within 1 working day. - Exclusion from school or a day-care facility is not required for any if the diseases discussed.

Management of an obstetric health care provider with acute parvovirus B19 infection

We report a case of an obstetrician with acute parvovirus B19 infection and the series of exposed pregnant women. Currently, there are no established guidelines regarding management of an obstetric health care provider with acute parvovirus B19 infection. We propose a management scheme of this clinical scenario.

Detection of IgE anti-parvovirus antibodies in human breast milk

Breast milk is a complex fluid, rich in nutrients and non-nutritional bioactive components, including antimicrobial factors, immunoglobulins, cytokines, and anti-inflammatory substances. Although IgE is implicated in viral immunity, its role in breast milk in parvovirus B19 immunity has not been studied. Total immunoglobulin levels of IgE, IgG, and IgE anti-parvovirus B19 antibodies were determined by ELISA and Western blot analysis in breast milk and in sera from a mother and her nursing infant (female, 10 mo). For specific IgE protein determination, breast milk was fractionated by chromatography on G-100 Sephadex; 3 peaks were collected and separated by SDS PAGE. The levels of total IgE in breast milk and its fractions were low (<2.4 ng/ml), and those of maternal and infant serum were negligible (18 and 4.3 IU/ml, respectively). Nevertheless, the breast milk and maternal and infant sera contained IgE anti-parvovirus B19 antibodies, even though the infant was never infected with parvovirus B19. Total serum levels of maternal IgG were within the normal range and those of infant IgG were low (473 mg/dl); total IgG in breast milk was not determined. Maternal serum contained some detectable IgG anti-parvovirus antibodies that were not present in infant serum or breast milk. Total maternal and infant serum levels of IgM and IgA were within the normal ranges. The presence of IgE anti-parvovirus B19 antibodies in breast milk suggests that IgE anti-viral antibodies are transmitted in breast milk and may provide protective responses in nursing children.

Molecular mechanism underlying B19 virus inactivation and comparison to other parvoviruses

BACKGROUND

B19 virus (B19V) is a human pathogen frequently present in blood specimens. Transmission of the virus occurs mainly via the respiratory route, but it has also been shown to occur through the administration of contaminated plasma-derived products. Parvoviridae are highly resistant to physicochemical treatments; however, B19V is more vulnerable than the rest of parvoviruses. The molecular mechanism governing the inactivation of B19V and the reason for its higher vulnerability remain unknown.

STUDY DESIGN AND METHODS

After inactivation of B19V by wet heat and low pH, the integrity of the viral capsid was examined by immunoprecipitation with two monoclonal antibodies directed to the N-terminal of VP1 and to a conformational epitope in VP2. The accessibility of the viral DNA was quantitatively analyzed by a hybridization-extension assay and by nuclease treatment.

RESULTS

The integrity of the viral particles was maintained during the inactivation procedure; however, the capsids became totally depleted of viral DNA. The DNA-depleted capsids, although not infectious, were able to attach to target cells. Comparison studies with other members of the Parvoviridae family revealed a remarkable instability of B19V DNA in its encapsidated state.

CONCLUSION

Inactivation of B19V by heat or low pH is not mediated by capsid disintegration but by the conversion of the infectious virions into DNA-depleted capsids. The high instability of the viral DNA in its encapsidated state is an exclusive feature of B19V, which explains its lower resistance to inactivation treatments.

Blood donor screening for parvovirus B19 in Germany and Austria

BACKGROUND

Although the main transmission pathway of parvovirus B19 (B19) is typically via the respiratory route, several transfusion-transmitted infections have been reported. To increase blood safety, all blood donations to our blood donor service have been screened by a B19 minipool real-time nucleic acid testing (NAT) since April 2000. Additional customers have been screened since the summer of 2003.

STUDY DESIGN AND METHODS

In total, 2.8 million donations from Germany and Austria were screened for B19 by real-time minipool NAT. A subgroup of 50 B19 DNA-positive donors was screened for B19 immunoglobulin G (IgG) and IgM antibodies and B19 DNA over a 6-month period. Results were compared to those of 100 B19 DNA-negative donors.

RESULTS

Data accumulated over the past 6 years indicate a high incidence period from May 2004 to January 2006. In total, the incidence was 12.7 and 261.5 per 100,000 donations with high virus loads equal to or above 10(5) and below 10(5) IU per mL, respectively. Median virus concentration in the case group was 4.85 x 10(7) IU per mL at Time Point T0 and was reduced to 4 x 10(2) IU per mL at the time of the next donation (3 months later). Neutralizing antibodies (VP2) were detected in all donations if virus load was reduced to less than 10(5) IU per mL.

CONCLUSION

The release of B19 DNA-positive blood products with a concentration of less than 105 IU per mL is thought to be safe due to the high level of neutralizing VP2 antibodies and is currently examined in a donor recipient infectivity study. In contrast, blood products with a high B19 DNA concentration (> or =10(5) IU/mL), some of which did not contain neutralizing antibodies, were discarded to protect at risk individuals.

Prevalence and quantitation of parvovirus B19 DNA levels in blood donors with a sensitive polymerase chain reaction screening assay

BACKGROUND

Blood donor parvovirus B19 DNA prevalence with sensitive nucleic acid test assays has recently been demonstrated to be higher than that found with assays designed to detect high viral titers in the plasma manufacturing sector.

STUDY DESIGN AND METHODS

Stored plasma aliquots from 5020 donations collected between 2000 and 2003 at seven US blood centers were tested. Testing was performed with a real-time B19 DNA polymerase chain reaction (PCR; TaqMan, Applied Biosystems) assay with a 50 percent limit of detection (LOD) of 1.6 IU per mL (95% confidence interval [CI], 1.2-2.1 IU/mL) and a 95 percent LOD of 16.5 IU per mL (95% CI, 10.6-33.9 IU/mL). Confirmation and quantitation of B19 DNA was accomplished by retesting of two additional subaliquots. Confirmed-positive specimens were tested for the presence of anti-B19 immunoglobulin M (IgM) and IgG with FDA-licensed assays.

RESULTS

B19 DNA prevalence was 0.88 percent (95% CI, 0.64%-1.2%). Among the 23 donations with B19 DNA titers of at least 20 IU per mL, the median DNA concentration was 105 IU per mL with an interquartile range of 42 to 481 IU per mL; the highest value was 1869 IU per mL. All B19 DNA-positive donations were positive for the presence of IgG and 10 (23%) were also positive for the presence of IgM; IgM seropositivity was associated with increasing DNA levels (p = 0.0013).

CONCLUSION

Low-level B19 DNA was detected in nearly 1 percent of donations. The 23 percent of DNA-positive donations with both IgM and IgG B19 antibody most likely represent acute resolving infection, whereas those with IgG but no IgM are most consistent with a more chronic and possibly persistent phase of B19 infection.

Inactivation of parvovirus B19 in human platelet concentrates by treatment with amotosalen and ultraviolet A illumination

BACKGROUND

The human erythrovirus B19 (B19) is a small (18- to 26-nm) nonenveloped virus with a single-stranded DNA genome of 5.6 kb. B19 is clinically significant and is also generally resistant to pathogen inactivation methods. Photochemical treatment (PCT) with amotosalen and ultraviolet A (UVA) inactivates viruses, bacteria, and protozoa in platelets (PLTs) and plasma prepared for transfusion. In this study, the capacity of PCT to inactivate B19 in human PLT concentrates was evaluated.

STUDY DESIGN AND METHODS

B19 inactivation was measured by a novel enzyme-linked immunosorbent spot (ELISPOT) erythroid progenitor cell infectivity assay and by inhibition of long-range (up to 4.3 kb) polymerase chain reaction (PCR), under conditions where the whole coding region of the viral genome was amplified. B19-infected plasma was used to test whether incubation of amotosalen with virus before PCT enhanced inactivation compared to immediate PCT.

RESULTS

Inactivation of up to 5.8 log of B19 as measured by the infectivity assay, or up to 6 logs as measured by PCR inhibition can be achieved under non-limiting conditions. Inactivation efficacy was found to increase with incubation prior to UVA illumination. Without incubation prior to illumination 2.1 +0.4 log was inactivated as determined by infectivity assay. When measured by PCR inhibition, inactivation varied inversely with amplicon size. When primers that spanned the entire coding region of the B19 genome were used, maximum inhibition of PCR amplification was demonstrated.

CONCLUSION

Under defined conditions, PCT with amotosalen combined with UVA light can be used to inactivate B19, a clinically significant virus that can be transmitted through blood transfusion, and heretofore has been demonstrated to be refractory to inactivation.

Evaluation of a new LightCycler reverse transcription-polymerase chain reaction infectivity assay for detection of human parvovirus B19 in dry-heat inactivation studies

BACKGROUND

Human parvovirus B19 (B19) is a widely distributed infectious agent, which causes a variety of illnesses including erythema infectiosum (fifth disease) especially in children, arthritis, aplastic crisis, and hydrops fetalis. B19 can be transmitted from asymptomatic blood donors to recipients of their blood components. Fifth disease has been reported in patients receiving red blood cells, platelets, solvent/detergent-treated plasma, and clotting factor concentrates.

STUDY DESIGN AND METHODS

A new B19-specific Light Cycler (LC) reverse transcription-polymerase chain reaction (RT-PCR) infectivity assay was developed for quantitative analysis of the infectivity of B19 in virus validation studies. The cycling conditions and the primers of the new assay were designed to amplify spliced RNA forms but not precursor RNA or B19 genome. One 50 percent infectious dose, determined on UT7/Epo-S1 cells of low passage, equaled 3.74+/-0.1 log international units of B19 DNA.

RESULTS

The efficiency of the dry-heat process (100 degrees C) on inactivation of B19 spiked and lyophilized with fibrinogen, a major component of the clotting factor concentrate and hemostatic dressing products, was investigated by use of B19-specific LC RT-PCR infectivity assay. At 1.3 to 1.7 percent residual moisture of fibrinogen, the infectivity of B19 was reduced dramatically by 3.3 to 5.1 log for 1 and 2 hours of dry-heat treatment, respectively. B19 infectivity was reduced 1.5, 2.8, and 3.8 log for 1, 2, and 3 hours of dry-heat treatment, respectively, at 0.5 to 0.7 percent residual moisture level.

CONCLUSION

These findings suggest that level of residual moisture of lyophilized fibrinogen with B19 spike correlated with a different resistance of B19 to dry-heat treatment, and that low moisture may stabilize virus against heat.

Heat sensitivity of human parvovirus B19

BACKGROUND AND OBJECTIVES

To date there has been no published report on a systematic evaluation of the heat sensitivity of human parvovirus B19 (B19) and the related safety of the plasma-derived fractionated products. In this study, we examined the heat sensitivity of B19 by using the infectivity assay with cultured cells.

MATERIALS AND METHODS

The heat sensitivity of B19 was examined by measuring the reduction in viral infectivity titres after heating liquid containing B19 at 60 degrees C. Viral infectivity was assayed by detection of viral antigens or viral mRNA in infected cells. As a control, canine parvovirus (CPV) was also heat-treated.

RESULTS

B19 displayed quite different inactivation kinetics to CPV when both were heated in liquid at 60 degrees C. In sharp contrast to the latter, B19 was rapidly inactivated within 1 h when the virus was suspended in 5% or 25% human serum albumin solution, phosphate-buffered saline, or complete medium. However, B19 appeared to be resistant to heat inactivation in liquid containing 60% sucrose.

CONCLUSIONS

The heat sensitivity of B19 in liquid was clearly different from that of CPV. Significantly, the efficiency to inactivate B19 and reduce its infectivity following heating in liquid was mainly affected by the composition of the solutions used for virus suspension.

TORCH Infections. Toxoplasmosis, Other (syphilis, varicella-zoster, parvovirus B19), Rubella, Cytomegalovirus (CMV), and Herpes infections

Perinatal infections account for 2% to 3% of all congenital anomalies. TORCH, which includes Toxoplasmosis, Other (syphilis, varicella-zoster, parvovirus B19), Rubella, Cytomegalovirus (CMV), and Herpes infections, are some of the most common infections associated with congenital anomalies. Most of the TORCH infections cause mild maternal morbidity, but have serious fetal consequences, and treatment of maternal infection frequently has no impact on fetal outcome. Therefore, recognition of maternal disease and fetal monitoring once disease is recognized are important for all clinicians. Knowledge of these diseases will help the clinician appropriately counsel mothers on preventive measures to avoid these infections, and will aid in counseling parents on the potential for adverse fetal outcomes when these infections are present.

1: Infections in pregnant women

Some infections are more serious in pregnant than non-pregnant women because of the potential for vertical transmission to the fetus or infant (eg, varicella, rubella, cytomegalovirus infection, toxoplasmosis and listeriosis). Pre-pregnancy or routine antenatal screening for presence of, or susceptibility to, some of these infections and appropriate management can prevent adverse fetal or perinatal outcomes; screening should include rubella IgG, hepatitis B surface antigen, serological tests for syphilis and HIV antibody. If certain other vertically transmissible infections are suspected because of a positive antenatal test result, confirmatory tests for maternal and, if indicated, fetal infection are essential before intervention is considered (eg, cytomegalovirus infection). For some vertically transmissible infections that are not readily preventable, appropriate management of maternal infection can reduce fetal damage (eg, toxoplasmosis).

Parvovirus B19 in pregnancy

Parvovirus B19 is a common, self-limiting, usually benign childhood virus that causes erythema infectiosum, also known as fifth disease. Acute infection in pregnancy can cause B19 infection in the fetus, leading to nonimmune fetal hydrops or fetal loss, depending on gestational age at the time of infection. Susceptibility to parvovirus B19 infection should be determined in selected pregnant women at high risk for exposure, and counseling should be provided regarding prevention, testing, and treatment options if exposed.

A rash of exanthems. How they affect children and pregnant women

BACKGROUND

Viral exanthems are a common problem for children, particularly during preschool years. Many of these infections have a dramatic impact on siblings, parents and other contacts. There may also be particular ramifications for pregnant contacts.

OBJECTIVE

To discuss some of the most common viral exanthems affecting children, in terms of the epidemiology, clinical features, diagnosis, and the management of both the patient and the contacts.

DISCUSSION

Recommendations are made for measles, rubella, parvovirus and varicella regarding immunisations, use of immunoglobulin, serological diagnosis and management of pregnant contacts.

Guidance for control of parvovirus B19 infection in healthcare settings and the community

Interventions for parvovirus B19 infection need to balance the low risk of infection at a population level with the potential for serious adverse outcome for particular groups, notably the fetus, people with haemoglobinopathies and the immunocompromised. This guidance aims to assist the local decision-making process to be as evidence-based as the available evidence allows.

[Parvovirus B19 infection]

In 1975, during blood screening for hepatitis B, Cossart et al. discovered the human parvovirus B19 (B19). It is a small, single strand DNA virus of the Parvoviridae family. This virus is widespread with 40-80% of adults showing evidence of infection. It is found in the respiratory secretions of viraemic patients and direct contact has been suggested as the most likely mode of transmission. Parenteral transmission is common during treatment with clotting-factor concentrates, but rarely occurs during transfusion with single donor products. Although B19 usually causes a self-limited illness, complications of infection can be severe and at times life threatening. In pregnant women, infection can lead to spontaneous abortions and hydrops fetalis and, in patients with haemolytic anaemias or in immunocompromised individuals, can induce aplastic crisis and chronic anaemias. The diagnosis can be made by indirect (testing for B19 antibodies) or direct methods (detecting B19 viremia). There are no vaccines or specific therapy currently available. Contact isolation is recommended for hospitalized patients.

Fifth disease in a small rural community. What are the consequences?

OBJECTIVE

To characterise the implications of an outbreak of human parvovirus in a small community.

METHOD

A community survey was conducted over a period of 18 months in a small rural town in Western Australia with a population of approximately 4300 people. Outbreak cases were assessed by the single general practice in the town. Notification of the survey was placed in both the schools and by advertisement in the local paper. Survey questionnaires distributed to community members were returned on a voluntary basis. After 12 months repeat surveys were sent to all adults who had responded to the initial survey.

RESULTS

Eighty-eight definite and 14 equivocal cases were identified as part of the outbreak, which occurred between late July 1994 and February 1995. Serological testing which confirmed human parvovirus B19 infection was available for 29% of cases. The highest attack rate was in the 5-9 year age group. One-third of cases were adults and 9% of them developed symptoms lasting longer than 6 months. Transient anaemia almost certainly due to parvovirus infection was identified in one adult women during the course of the outbreak. No pregnant woman suffered any adverse fetal outcome as a result of human parvovirus infection.

CONCLUSION

In an outbreak of parvovirus, children will be most commonly affected although adults can develop polyarthralgia/arthritis which may persist for several months and some may suffer transient anaemia. Pregnant women are potentially at risk of the development of fetal hydrops and fetal death, but advice to them can be based on the estimate of a less than 1% risk of adverse fetal outcome due to parvovirus infection.

Parvovirus B19 outbreak in a rehabilitation hospital

A nurse (index case) at a rehabilitation hospital was diagnosed with acute parvovirus B19 infection. A 2-year-old male patient was identified as the source patient. The epidemiological investigation focused on 15 individuals with symptomatic disease or risk factors for complications of parvovirus B19 infection. Serologic testing confirmed parvovirus B19 infection in the index case and source patient and identified a second health care worker who possibly contracted acute parvovirus B19 infection through nosocomial transmission. Parvovirus B19 infection can cause serious complications in pregnant women, persons with chronic hemolytic anemia, and persons with immunodeficiencies. Measures to control the transmission of parvovirus B19 infection should be part of the infection control plan at rehabilitation hospitals.

Parvovirus B19 infection

Human parvovirus B19, discovered in 1974, is a single-stranded DNA virus which causes erythema infectiosum, arthralgia, aplastic crisis in patients with red cell defects, chronic anaemia in immunocompromised patients, and fetal hydrops. Seroprevalence in developed countries is 2-10% in children less than 5 years, 40-60% in adults more than 20 years, and 85% or more in those over 70 years. The virus may be transmitted by the respiratory route and by transfusion of infected blood and blood products. After an incubation period of six to eight days, viraemia occurs, during which reticulocyte numbers fall dramatically resulting in a temporary drop in haemoglobin of 1 g/dl in a normal person. Clearance of viraemia is dependent on development of specific antibody to the B19 structural proteins, VP1 and VP2. The red cell receptor for the virus is blood group P antigen. Diagnosis in immunocompetent persons depends on detection of specific IgM in serum. Diagnosis in immunocompromised persons depends on detection of B19 antigen or DNA in serum. There is no specific treatment for B19 infection; however, human normal immunoglobulin may be used as a source of specific antibody in chronically infected persons. A recombinant parvovirus B19 vaccine is under development.

Parvovirus B19: an expanding spectrum of disease

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[Transmission of parvovirus B19 by blood and blood components]

OBJECTIVE

To determine the clinical significance of parvovirus B19 (B19) and the potential risk of transmission by blood or plasma products. Procedures to avoid this transmission are discussed.

DATA SOURCES AND SELECTION CRITERIA

Known physico-chemical data of autonomous parvoviridae, and studies on the incidence of B19 in blood or plasma products, were considered. Data on B19 infection published by the author and/or other investigators.

RESULTS

B19 occurs endemically in Germany. The incidence of B19 virus-positive blood donations is approximate 0.01-0.03%. Despite using virus-inactivating procedures transmission of B19 by clotting factor concentrates cannot be excluded at present.

CONCLUSIONS

Transmission of B19 virus by blood or plasma products can be avoided by testing single donations for B19-specific antibodies by enzyme-immunoassay or B19 DNA by polymerase chain reaction.

B19 parvovirus DNA in solvent/detergent-treated anti-haemophilia concentrates

A transfusional B19 parvovirus infection may have severe consequences in immunocompromised hosts. The presence of B19 DNA was investigated with a polymerase chain reaction (PCR) assay in 30 batches of solvent/detergent-treated clotting factor concentrates (12 batches of factor VIII, 16 batches of factor IX, 1 batch of factor VII, and 1 batch of PPSB). B19 DNA was detected in 6 (20%) batches, including 3 factor VIII and 3 factor IX concentrates. Because of the frequency of B19 DNA in batches of clotting factors, measures to prevent transfusional risk of B19 infection via these blood products are justified, especially in recipients immunocompromised by HIV infection.

Human herpesvirus-6 and parvovirus B19 infections in children

It was proved in the 1980s that human herpesvirus-6 and human parvovirus B19 cause diseases in humans. Human herpesvirus-6, a newly recognized herpesvirus, is a causative agent of exanthem subitum. The virus produces broad clinical features; complications, including fatal outcome, are frequently activated in immunosuppressed conditions such as organ transplantation. Parvovirus B19, a small-DNA virus, infects erythroid progenitor cells. Systemic infection with parvovirus B19 is responsible for several clinical entities, such as erythema infectiosum, arthropathy, aplastic crisis, fetal death, and other disease conditions, including those in immunosuppressed hosts. Reliable diagnostic technologies and carefully designed clinical, immunologic, and virologic studies will fully delineate the clinical significance of both viral infections.

Detection of parvovirus B19 in donated blood: a model system for screening by polymerase chain reaction

A highly sensitive and rapid method for routinely screening large numbers of donated blood units for parvovirus B19 by the polymerase chain reaction (PCR) was developed. Over a 3-month trial period in Edinburgh, B19 DNA was detected in 6 of 20,000 consecutive units of blood (0.03%), in concentrations ranging from 2.4 x 10(4) to 5 x 10(10) copies of viral DNA per ml. Seroconversion for B19-specific immunoglobulin M and immunoglobulin G and disappearance of circulating B19 DNA occurred in the interval between donation and recall in four of the five implicated donors who could be recalled. B19 DNA was detected in 18 of 27 separate batches of non-heat-treated factor VIII and IX concentrate manufactured from donated plasma unscreened for B19 DNA. Dry-heat treatment at 80 degrees C for 72 h reduced but did not always eliminate detectable B19 from factor VIII concentrates, consistent with recent observations that current methods for virus inactivation during blood product manufacture are insufficient to entirely eliminate B19 infectivity. The methods developed in this study for PCR screening could be applied routinely to prevent transfusion of B19 in blood and blood products and could play an important role in the prevention of iatrogenic transmission of infection. PCR screening could also be used for detection and exclusion of a range of other transmission-associated viruses for which current serological detection methods are only partially effective.

Parvovirus B19 outbreak in a children's ward

Parvovirus B19 infection can cause severe complications in pregnant women, individuals with haemolytic anaemia, and those who are immunocompromised. In a hospital outbreak of this infection, a balance should be struck between protection of these individuals and the maintenance of medical services. The index case of an outbreak of parvovirus B19 infection among staff and patients of a paediatric ward was not identified. 58 members of staff were screened for B19 markers and 4 of the 6 susceptible men and 6 of the 24 susceptible women became infected (p = 0.05) as defined by serum IgM and viraemia. 1 of the 11 adults (10 members of staff and 1 parent) infected remained symptom-free. 12 immunocompromised patients were also assessed, and symptom-free infection developed in 2 of these. During the outbreak staff with symptoms were put on sick leave, immunocompromised patients (there were none with haemolytic anaemia) were given normal human immunoglobulin and nursed in single rooms by B19 IgG-positive, IgM-negative staff, and the ward was closed to B19 IgG-negative pregnant women. However, the limitation of spread of infection cannot be attributed with certainty to the measures taken.

[Human Parvovirus B19--really only fifth disease? Unusual disease course in children and adolescents]

The human parvovirus B19 agent causes infectious erythema (fifth disease). However, a wide range of other pathological manifestations may also be seen: atypical exanthema, ARD (also obstructive forms, e.g. bronchiolitis), acute gastroenteritis, chronic anemia or aplastic crises (in constitutional or malignant hematological diseases or immunological deficiency), arthralgia/arthritis (e.g. rheumatoid arthritis, jcA), diseases of the central nervous systems (e.g. febrile convulsions in young children), lymphadenopathies (e.g. lymphadenitis mesenterialis or pseudoappendicitis); prenatal infection can lead to fetal death (not malformations!). Infection occurring concomitantly with vaccination may suggest complications of the latter. To clarify the true etiological situation, modern laboratory investigations are then required. Vaccination against parvovirus B19 (initially indicated in the case of non-immune girls and women wanting children) is a desirable future development.

[Incidence of congenital infections]

The discussions on the pros and cons of obstetric screening for connatal infections have been going on for years. We, therefore, conducted a prevalence study of the most common connatal infections. HIV infection, rubella and syphilis were not subjects of this study. We analysed the relevance of these infections in 512 pregnant women and their newborn infants at the moment of delivery. Further serological tests were run three months post partum, if necessary even for a longer period. Cytomegaly IgG antibodies were found in 46% of the examined women, IgM antibodies in 1.3%. Women under the age of twenty and women of low social standing showed the highest rate of prevalence of infection with CMV. The prevalence of IgG antibodies against parvovirus B 19 was 29%. In 10 mothers, positive IgM titers were found at the time of delivery. In all these women, pregnancies had been uneventful. However, 9 mothers exhibited a significantly raised abortion rate within the last 20 months before delivery. 7 of 512 women turned out to be HBs antigen carriers, 3 women and their babies were anti-HCV positive. The prevalence of toxoplasmosis IgG antibodies was 36%, of IgM antibodies 5.3%. By further investigation (Toxo ISAGA, Toxo IgA) we were able to detect one child with connatal toxoplasmosis. We conclude, that screening for parvovirus B 19 and hepatitis C is required only, if there are contact or clinical hints that the patients might have acquired either one of these infections. But we postulate, that a routine screening programme for hepatitis B and toxoplasmosis should be carried out in all pregnant women.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe nonimmune hydrops secondary to parvovirus B-19 infection: Spontaneous reversal in utero and survival of a term infant

We present a case of intrauterine infection with parvovirus B-19 and accompanying severe nonimmune hydrops at 26 weeks' gestation. The fetus showed progressive recovery on ultrasound. A term infant was delivered with hepatosplenomegaly as the only abnormality.