An outbreak of erythema infectiosum associated with human parvovirus infection

Preliminary X-ray crystallographic investigation of human parvovirus B19

Crystals that diffract X rays to at least 8 A resolution have been grown from human B19 parvovirus empty capsids. These particles consist of VP-2 derived from a baculovirus expression system. This is possibly the first time that a self-assembled empty viral capsid, grown in other than normal host cells, has been crystallized. Partial X-ray diffraction data have been collected using synchrotron radiation. The space group is P2(1)3 with a = 362 A. The particle position in the crystal cell is given, at least roughly, from packing considerations.

Evaluation of a synthetic-peptide enzyme-linked immunosorbent assay for immunoglobulin M to human parvovirus B19

A synthetic peptide corresponding to a part of the virus protein 1-virus protein 2 overlapping region of human parvovirus B19 was used in an indirect enzyme-linked immunosorbent assay. Antibodies of the immunoglobulin (Ig) M class were measured in serum samples from patients with erythema infectiosum and controls. In comparison with an IgM assay using native B19 viral antigen, the peptide antigen assay was 92% sensitive and 87% specific. B19 IgM reactivities were seen in a limited number of children with other viral diseases. Specific IgM reactivities to short synthetic viral peptides have previously been reported only with Epstein-Barr virus. Since other sources of viral antigen are limited, the peptide antigen assay may be a useful alternative for the diagnosis of B19-associated disease in human beings.

Viruses and bone marrow failure

Many agents are associated with bone marrow failure, including toxins, inherited metabolic defects, ionizing radiation, and viral infection. In most cases, the etiologic agent is unknown. Many of these unclassified cases have symptomatic, immunologic, or epidemiologic similarities to viral infections. Viruses from different taxonomic families have been implicated in bone marrow failure syndromes, and they appear to cause hematosuppression by a variety of mechanisms. Some of the viruses involved in relatively well characterized suppressive interactions will be reviewed, including parovovirus B19, dengue, hepatitis viruses, Epstein-Barr virus, cytomegalovirus and the human immunodeficiency virus.

New oligopeptide immunoglobulin G test for human parvovirus B19 antibodies

A new, highly sensitive and specific enzyme immunoassay using oligopeptides as antigen (enzyme-linked immunosorbent assay [ELISA] B19-OP) for detecting parvovirus B19-specific immunoglobulin G (IgG) was established. As antigens, B19-specific oligopeptides of 24 and 30 kDa derived from a 196-kDa fusion protein of beta-galactosidase and viral capsid protein (VPI) of B19 after CNBr cleavage and separation by high-pressure liquid chromatography were used. Of 139 serum specimens tested in parallel for anti-B19 IgG by standard ELISA using B19 particles as antigen and by ELISA B19-OP, 73 (52.5%) were positive and 63 (45.3%) were negative in both tests, and 3 (2.2%) were negative by standard ELISA but positive by ELISA B19-OP and by immunoblot. By using ELISA B19-OP, it was possible to detect anti-B19 IgG in an asymptomatic blood donor 4 weeks after acute infection, and anti-B19 IgG titers of 10(-5) could be measured in convalescent-phase sera.

Human parvovirus B19 infected fetal liver as a source of antigen for a radioimmunoassay for B19 specific IgM in clinical samples

A radioimmunoassay for human parvovirus B19 IgM was developed using virus antigen derived from infected fetal liver obtained post mortem. The specificity and sensitivity of this assay, compared with an established radioimmunoassay using serum antigen, was determined by testing 126 sera by both techniques. The results obtained demonstrated close concordance. False negative results were not obtained using fetal liver antigen in 58 tests on known B19 IgM negative sera. Sixty-four IgM positive sera gave positive results using fetal liver derived antigen and the results obtained were quantitatively similar. Four sera gave false positive results using liver antigen but at a very low level. In view of these results we were able to establish a routine diagnostic service for B19 IgM using fetal liver derived antigen, and the results obtained on the first 459 clinical specimens are presented.

In situ hybridization for the detection of human parvovirus B19 nucleic acid sequences in paraffin-embedded specimens

Parvovirus infection of pregnant women leading to a transplacentar infection of the fetus may result in hydrops fetalis, and ultimately in intrauterine death of the fetus. In situ hybridization with a biotinylated as well as with a 35S-labeled probe for human parvovirus B19 was performed on formalin-fixed paraffin-embedded (FFPE) tissue from a fetus suffering from non-immunologic hydrops fetalis. Histology was suggestive of viral infection probably with human parvovirus. Parvovirus DNA could be detected and precisely localized mainly in the nuclei of erythroid precursors cells within fetal blood vessels of all organs examined. There was no detection of B19 nucleic acid in parenchymal cells of the placenta or the fetal organs, nor within maternal blood cells. These findings are in agreement with the well-known properties of animal parvoviruses to replicate exclusively in proliferating cells. Taking into consideration the problems in diagnosing human parvovirus infection by light microscopy, we conclude that in situ hybridization with an appropriate non-radioactive probe is a valuable, rapid and safe complementary detection method for the diagnosis and study of human parvovirus infections. The 35S-labeled probe is more sensitive than the biotinylated probe, but has the disadvantages of lower resolution of the signal, longer duration of the assay, the hazard of radioactivity and the shorter shelf-life of the probe.

Erythema infectiosum and pregnancy-related complications

Erythema infectiosum, an acute, communicable viral disease with a highly distinctive exanthem, follows the usual course of a self-limiting benign disease. In pregnant women, however, it may be associated with fetal death and nonimmune hydrops fetalis. Because of the association of human parvovirus (HPV) B19 infection with fetal damage we reviewed the current knowledge of the clinical aspects of erythema infectiosum, focusing on pregnancy and fetal outcome, to determine the magnitude of fetal risk and offer recommendations for management. Among 180 infected pregnant women 44 fetal deaths (24%) occurred, 1 to 12 weeks after the infection was noted. Pregnant women should be advised that (a) because of the high prevalence (up to 65%) of anti-HPV B19 IgG antibody among adults most of them are not at risk and (b) if maternal infection does occur therapeutic abortion is not indicated since intrauterine infection causes fetal death more often than abnormal development. Infection should be suspected in pregnant women who exhibit the symptoms of erythema infectiosum with or without arthropathy. They should be monitored for an elevated serum alpha-fetoprotein level (indicating fetal aplastic crisis) and undergo serial ultrasonography for the detection of hydrops fetalis. Although the incidence of congenital malformation is no higher than the expected rate in the general population (3% to 5%), the precise incidence of fetal adverse outcomes remains unknown and requires investigation in larger, prospective studies.

A review of outbreaks of infectious disease in schools in England and Wales 1979-88

In this review of 66 outbreaks of infectious disease in schools in England and Wales between 1979-88, 27 were reported from independent and 39 from maintained schools. Altogether, over 8000 children and nearly 500 adults were affected. Most of the outbreaks investigated were due to gastrointestinal infections which affected about 5000 children: respiratory infections affected a further 2000 children. Fifty-two children and seven adults were admitted to hospital and one child with measles died. Vaccination policies and use of immunoglobulin for control and prevention of outbreaks in schools have been discussed.

Expression of an antigenic polypeptide of the human parvovirus B19

The DNA fragment of the human parvovirus B19, with 715 nucleotides between nucleotide positions 3141-3856 was expressed in Escherichia coli as a beta-galactosidase fusion protein. The plasmid vector pSS20d used for this purpose permits cleavage of the viral gene product from the beta-galactosidase moiety by collagenase. After purification by p-aminophenyl-beta-D-thiogalactoside-sepharose and superose, a soluble protein with a molecular mass of 28 kDa was isolated. It represents a common part of the viral capsid proteins VP1 and VP2. This bacterially derived parvoviral gene product can be used for detection of anti-B19 antibodies in human sera.

Prospective study of human parvovirus (B19) infection in pregnancy. Public Health Laboratory Service Working Party on Fifth Disease

OBJECTIVE

To determine the fetal infection rate and outcome of pregnancy among women who acquire infection with human parvovirus (B19) in the antenatal period.

DESIGN

Prospective study of infected pregnancies till time of delivery or abortion with virological investigation of fetuses, neonates, and 1 year old infants.

SETTING

England and Wales during 1985-8.

PATIENTS

190 Pregnant women with serologically confirmed B19 infection in pregnancy, their fetuses, neonates, and 1 year old infants.

RESULTS

Of 186 mothers who elected to go to term, 156 (84%) delivered a normal baby. Follow up of 114 of these infants to the age of 1 year disclosed no appreciable abnormalities, although 27 had serological evidence of intrauterine infection. The overall fetal loss rate (30 cases; 16%) was similar to that in an uninfected antenatal sample (unmatched), but there was a pronounced excess of fetal loss in the second trimester in the B19 infected mothers (11.8%; 95% confidence interval 6.8% to 17.8%). Based on virological findings in the aborted fetuses the risk of fetal death due to B19 in an infected pregnancy was estimated to be 9%. The transplacental transmission rate was estimated to be 33%.

CONCLUSIONS

Most women with B19 infection in pregnancy had a satisfactory outcome, but there was nevertheless a substantial risk of fetal loss in the second trimester. In view of the absence to date of any evidence of damage to babies who survive maternal infection therapeutic termination of pregnancy is not indicated.

Transmission of human parvovirus B19 by coagulation factor concentrates

The prevalence of antibody to human parvovirus B19 was determined in 86 children with congenital bleeding disorders. Forty-seven of 53 boys (89%) receiving non-heat-treated factor VIII or prothrombin complex concentrates were anti-B19 IgG positive compared with 38% of their age-matched controls and 48% of children treated with cryoprecipitate. Acute B19 virus infection occurred in 2 boys 3-4 weeks after they had received the same batch of commercial factor VIII concentrate. Of 11 susceptible children who had only received heat-treated National Health Service factor VIII concentrate (8Y), 1 acquired anti-B19 IgG. This suggests that 8Y heat-treated concentrate has a much reduced risk of transmitting B19 virus and, by implication, other less heat-stable viruses such as human immunodeficiency virus.

The prevalence of antibody to human parvovirus B19 in Rio de Janeiro, Brazil

During 1985 and 1986 serum samples were collected from the Rio de Janeiro population and examined for the presence of IgG antibody to human parvovirus B19. No difference in prevalence was found between males and females. Antibody prevalence rose from 35% in children less than five years old to almost 80% in children aged eleven to fifteen years. The antibody prevalence in individuals over 50 years old was over 90%.

Detection of human parvovirus B19 DNA by using the polymerase chain reaction

The polymerase chain reaction (PCR) was investigated for detecting human parvovirus B19 (B19) DNA in sera. Three pairs of oligonucleotides were evaluated as primers. The best oligonucleotide pair spanned 699 nucleotides, including the region common to VP1 and VP2. After PCR amplification of B19 DNA in serum, a 699-nucleotide DNA fragment was detected on agarose gels. This DNA fragment was B19 DNA, because after Southern transfer it hybridized to a 19-nucleotide internal probe and contained a single PstI cleavage site. Dot blot hybridization with a radiolabeled cloned portion of the B19 genome as a probe was compared with PCR. PCR was 10(4) times more sensitive than dot blot hybridization and, with an internal radiolabeled probe, 10(7) times more sensitive than dot blot hybridization. Of 29 serum specimens from 18 patients with proven B19 infections, 24 were PCR positive. None of 20 serum samples from uninfected controls were positive. Of 22 serum samples positive for immunoglobulin M to B19, PCR detected B19 DNA in 17. Seven serum samples lacking immunoglobulin M were PCR positive. PCR detected B19 DNA in urine, amniotic fluid, pleural fluid, ascites, and leukocyte extracts. PCR is a rapid and simple method for diagnosing infections with human parvovirus B19 but must be combined with serologic tests for immunoglobulin M to B19, especially when testing only a single serum sample.

Concurrent outbreaks of influenza and parvovirus B19 in a boys' boarding school

In the spring term of 1985 there was a protracted outbreak of upper respiratory tract febrile illness consistent with a clinical diagnosis of influenza in a boys' boarding school, which lasted from 23 January to 29 March. Although influenza virus infection was confirmed in 89% of cases in the first half of the term, 53% of the cases which occurred in the second half of the term had no evidence of infection with influenza virus. Between 5 February and 31 March 28 boys presented with skin rashes consistent with a clinical diagnosis of erythema infectiosum; 68% of these were associated with parvovirus B19. Investigation of the cases of clinical influenza with no identified respiratory pathogen revealed a 58% infection rate with B19. B19 DNA was identified in either throat swabs or acute stage bloods of nine pupils with influenza-like symptoms. Cohort studies revealed that 44% of pupils aged 15-16 years were immune before the outbreak compared with only 17% of pupils aged 11-12 years. Infection in the younger group was common and was associated with influenza-like illnesses as well as rashes. Forty-eight per cent of those who did not report any symptoms were also infected with B19.

A genetically engineered cell line that produces empty capsids of B19 (human) parvovirus

B19 parvovirus is pathogenic in humans, causing the common childhood exanthem fifth disease and bone-marrow failure, both acute (transient aplastic crisis of hemolysis) and chronic (pure erythrocyte aplasia in immunodeficiency). The virus is tropic for a human red cell progenitor cell, and failure to culture B19 in a cell line has limited its clinical study. We cotransfected the right half of the cloned B19 genome and a minigene derived from the human dihydrofolate reductase gene (DHFR) into dhfr--Chinese hamster ovary cells and screened selected clones by RNA analysis; after amplification in methotrexate, clones were tested for capsid protein expression. A cell line, designated 3-11-5, stably expressed nearly full-length transcripts for the two capsid proteins. These cells produced the major and minor structural protein species in natural proportions that self-assembled into virion capsids. Capsids from 3-11-5 cells could be separated from virions by sucrose gradient sedimentation and had the density on cesium chloride isopycnic sedimentation of empty parvovirus capsids. Capsid protein was present in both nuclei and cytoplasm on immunofluorescence study but fractionated with the cytosol on purification. Empty capsid production was equal to or greater than virion production by infected bone-marrow cells, 1000-2000 capsids per cell, but cell growth was not diminished by capsid production. This cell line will be useful in developing practical assays for B19 parvovirus antibody and a vaccine for the virus, as well as potentially serving as a packaging cell line for gene therapy.

Fifth disease in children living in Belém, Brazil

Acute sera from two children suffering from an illness with an erythematous rash were positive for B 19 virus specific IgM antibody, as tested by a capture radioimmunoassay. The first patient, a two year old boy, presented with a cutaneous rash of six days duration, the second was a four year old girl, sister of the first patient, who was examined at the same time and had a three day history of cutaneous rash.

Erythema infectiosum in a primary school: investigation of an outbreak in Bury

Between January and April 1987, 97 of 302 (32%) children attending a primary school in Bury, Lancashire, were affected by an exanthematous illness. The duration and extent of the episode caused considerable local interest and anxiety. Examination of 6 serum specimens obtained during the subsequent investigation demonstrated evidence of recent Human Parvovirus B19 infection in 3 children and 1 teacher. No evidence of recent rubella virus infection was found. The investigation of the episode is discussed in the context of problems which may occur in the management of similar outbreaks.

Human parvovirus B19 infection among hospital staff members after contact with infected patients

In the spring and summer of 1988, two separate outbreaks of an illness with a rash resembling erythema infectiosum occurred among members of the nursing staff of the Children's Hospital of Philadelphia. The sources were two adolescent patients with sickle cell disease and aplastic crisis who had unsuspected parvovirus infection. Tests for IgM and IgG antibodies to parvovirus B19 were positive in both patients, and electron microscopical examination showed parvovirus-like particles in the early serum samples. Of 40 health care workers exposed to infected patients, 12 (30 percent) were infected, 2 (5 percent) were possibly infected, 8 (20 percent) had evidence of a past infection with B19, and 18 (45 percent) remained seronegative. Attack rates among the susceptible contacts were 36 percent in the first outbreak and at least 38 percent in the second. Clinical symptoms began a mean of 12.6 days after exposure and included malaise, rash, and joint pain. We conclude that hospital workers are at risk of contracting nosocomial erythema infectiosum from patients with parvovirus-associated aplastic crisis. We recommend that all patients with hereditary hemolytic anemias who are admitted with a febrile illness be evaluated for aplasia and promptly placed in respiratory and contact isolation if aplastic crisis is suspected.

Seroprevalence of human parvovirus B19 infection in Sao Tomé and Principe, Malawi and Mascarene Islands

The prevalence of antibodies to human parvovirus B19 (anti-B19 IgG) in sera (n = 577) from Sao Tomé and Principe, Malawi and Mascarene Islands (Mauritius and Rodriguez Islands) was determined by antibody capture ELISA. The B19 prevalence was 51.5% on Sao Tomé and Principe, 58.4% in Malawi, and 55.0% on the Mauritius mainland and 2.2% on Rodriguez Island, indicating that B19 virus is highly prevalent not only in Europe, Japan and the Americas but also in the African region. Rodriguez Islands has a very low B19 prevalence.

Propagation of human parvovirus B19 in primary culture of erythroid lineage cells derived from fetal liver

Erythroid lineage cells derived from fetal liver were demonstrated to be target cells for human parvovirus B19 infection. B19 virus antigen-positive serum was inoculated into primary cultures containing erythroid lineage cells enriched from fetal liver. The B19 virus antigen was detected on about 5% of cells in the culture by immunofluorescence staining, and the stained cells were identified as erythroid lineage cells by double staining with anti-B19 virus-positive serum and anti-erythroid lineage monoclonal antibody. The immunofluorescence staining study also revealed that the B19 virus antigen localized in the nucleus and the periphery of cytoplasm. We also detected B19 virus DNA, which was generated by replication in the infected cells, not only in the cells but also in the culture supernatants, in which the amount of B19 DNA increased depending on the period of culture, indicating that the cells infected with B19 virus produced B19 virus and released it into the medium. The ability of B19 virus released into the medium to infect fetal erythroid lineage cells was demonstrated quantitatively. Because of the absence of any cytopathic effect of B19 virus during culture periods of at least 15 days, this culture system should be useful in the study of B19 virus replication and in vitro generation of B19 virus. In addition, the present study may contribute to a better understanding of the pathogenesis of hydrops fetalis, which is probably associated with B19 virus infection during pregnancy.

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.

Antenatal diagnosis and palliative treatment of non-immune hydrops fetalis secondary to fetal parvovirus B19 infection

Hydrops fetalis was diagnosed at 22 weeks. An ultrasound examination demonstrated cardiomegaly and a fetal blood specimen obtained by cordocentesis revealed thrombocytopenia, anaemia, and neutropenia. Fetal paracentesis yielded straw-coloured fluid with electrolytes indicative of a transudate. Non-enveloped icosahedral viral particles approximately 23 mm in diameter were visualized in the ascitic fluid by electron microscopy. Immune electron microscopy confirmed human parvovirus B19. Direct fetal digitalization led to a reduction in umbilical artery resistance, a decline in the abdominal circumference from 20.3 to 17.8 cm, and resolution of the ascites within 72 h. Despite this dramatic response to therapy, fetal death occurred on day 5 of treatment. The initial maternal serum was positive for anti-B19 IgM and IgG antibodies. Electron microscopy of fetal cardiac tissue obtained post-mortem revealed intranuclear viral particles typical of B19, confirming the antenatal diagnosis of myocarditis. This case demonstrates that direct viral identification is applicable to prenatal diagnosis. To our knowledge, this is the first reported case of the antenatal diagnosis and palliative treatment of fetal viral infection.

Rapid detection of human parvovirus B19 DNA by dot-hybridization and the polymerase chain reaction

The results of a comparison of three DNA-detection methods for human parvovirus B19 DNA are described. The sensitivity of detection of virus from hybridization assays using 32P-radiolabeled DNA and RNA probes was compared with a method for enzymatically amplifying specific target DNA sequences (polymerase chain reaction). B19 virus DNA was detected using a radiolabeled DNA probe at serum dilutions of 10(-3), equivalent to approximately 3 pg of viral DNA. Using radiolabeled RNA probes even 0.3 pg of viral DNA was detectable. The polymerase chain reaction was more sensitive than the hybridization assays: 100 fg of viral DNA was easily detectable by electrophoresis on agarose and after subsequent hybridization with a radiolabeled probe approximately 10 fg of B19 DNA was detected. The sensitivity of the PCR, combined with the simplicity and reduced time scale, demonstrates the potential of this technique as an additional method for routine diagnosis of B19 infections.

A new peptide for human parvovirus B19 antibody detection

A serological assay for human parvovirus B19 was developed. Linear overlapping synthetic peptides were synthesised according to parts of open reading frames 1 and 2. A region at the N-terminus of viral protein VP2 detected serological reactivity in indirect enzyme-linked immunosorbent assays for IgG and IgM with known seropositive human sera. A cyclized peptide taken from this region, amino acids 284-307, gave the best selective reactivity with seropositive and seronegative sera. The peptide assay appears suitable for further studies of B19 infections and their complications.

Viruses and bone marrow failure

Some generalizations can be drawn from a review of virus-associated bone marrow failure. The story of B19 parvovirus illustrates that viral infection may be an occult cause of marrow failure. Although the epidemiology of transient aplastic crisis suggested a viral aetiology, the implication of a single virus was surprising; the sporadic appearance of chronic bone marrow failure in immunosuppressed persons has had none of the features of a viral illness. The incrimination of parvovirus in these cases required development of specific immunological and molecular assays. Human and animal retrovirus studies have shown that small changes in the virus genome can have dramatic effects on the biology of the infectious agent and its pathogenicity in infected hosts. In Epstein-Barr virus infection, the host's immune response may play a more important role in mediating disease than virus cytotoxicity. Finally, the association of aplastic anaemia with hepatitis may be underestimated because of the inability to diagnose virus infection without obvious liver disease. The true spectrum of bone marrow disease due to virus infection is not known.

Parvovirus infections. From benign to life-threatening

Erythema infectiosum, aplastic crisis, intrauterine fetal demise, and an acute polyarthralgia syndrome can all be caused by human parvovirus B19. The major pathophysiologic effect of infection seems to be cessation of erythropoiesis as a result of cytolytic infection of red cell precursors. Erythema infectiosum is a benign disease that usually occurs in childhood. The acute polyarthralgia syndrome is likewise benign, and patients in whom parvovirus infection has been confirmed by serologic testing can be reassured that their joint symptoms are likely to be self-limited. Parvovirus-induced aplastic crisis in a patient with chronic hemolytic anemia is life-threatening but can be reversed with blood transfusions if recognized promptly. Parvovirus infection during pregnancy clearly increases the risk of fetal demise, and parental anxiety is understandably high. An organized approach using a combination of tests to monitor mother and fetus can provide optimal care in these cases.

Erythema infectiosum (fifth disease) occurrence in Iowa

Review of Iowa school nurse surveillance for erythema infectiosum, or fifth disease (FD), since 1973 demonstrated occurrence yearly except 1985 without a clear pattern of disease spread. We conclude that FD is more common than previously recognized. Failure to identify cases representing the background incidence of disease may account for underreporting.

Human parvovirus B19: ELISA and immunoblot assays

An ELISA for the detection of specific IgM and IgG against human parvovirus B19 (anti-B19 IgM and IgG) and B19 antigen is described. With ELISA anti-B19 IgM could be detected for up to 20 weeks after viraemia. Four to five months after B19 infection anti-B19 IgG titres range between 10(-6) and 10(-7). Nonspecific reactions with rheumatoid factor or IgM against rubella were not found. The ELISA for B19 antigen was shown to be as sensitive as DNA hybridisation. With immunoblotting two viral proteins of 83 kd (VP1) and 58 kd (VP2) were demonstrated. After acute infection antibodies to VP2 appear before antibodies to VP1. Immunoblotting might be used in pregnancy to determine the time of maternal infection. In a survey of a B19 outbreak in a school for medical technology, 6 (28.6%) of 21 non-immune females seroconverted.

Human parvovirus B19-induced vesiculopustular skin eruption

Erythema infectiosum, fifth disease, is a usually benign macular or maculopapular exanthem of childhood caused by the human parvovirus B19. A 27-year-old woman with a serologically documented human parvovirus infection who presented with a hemorrhagic exanthem and enanthem with areas of pustules and pseudo-pustules is described. The histologic findings were unusual because they combined the histologic features of morbilliform and vesiculopustular viral lesions. This case serves to underscore the occurrence of human parvovirus infection in adults. Further, it demonstrates the need to include parvovirus infection in the differential diagnosis of virally induced vesiculopustular skin eruptions.

Fetal infection with human parvovirus B19

The case of premature infant with nonimmune hydrops secondary to human parvovirus B19 infection is presented. The infection was not suspected clinically. The fetal autopsy showed intranuclear inclusions in erythroid cells that stained positively with a DNA hybridization probe for B19 parvovirus.

Novel transcription map for the B19 (human) pathogenic parvovirus

The B19 parvovirus, a small single-stranded DNA virus of 5.4 kilobases, is pathogenic in humans. B19 has remarkable specificity for erythroid progenitor cells and has been propagated in vitro only with human erythroid bone marrow. Replication of viral DNA and the viral protein products of B19 appear similar to those of other animal parvoviruses. However, B19 transcription had unusual features in comparison with that in other animal parvoviruses. At least nine overlapping poly(A)+ transcripts were identified in infected cells; all but one contained large introns. B19 differed from other parvoviruses in the initiation of all transcripts at a strong left side promoter (p6) and the absence of a functional internal promoter; the presence of short 5' leader sequences of about 60 bases and very large introns for RNAs encoded by the right side of the genome; two separate transcription termination sites, in contrast to cotermination at the far right side of the genome for other parvoviruses; the probable utilization by three transcripts of a variant polyadenylation signal (ATTAAA or AATAAC) in the middle of the genome; and the abundance of two unique transcripts from the middle of the genome which did not code for capsid proteins. The unusual transcription map of B19 suggests that regulation of the relative abundance of transcripts occurs by splicing and termination-polyadenylation events rather than by promoter strength. In combination with the published nucleotide sequence, the novel transcription map separated the pathogenic B19 virus at a molecular level from other animal parvoviruses and human adeno-associated virus.

Human parvovirus infections

Discovered by chance in 1974, the human serum parvovirus B19 is at present the only recognized, autonomous, pathogenic human parvovirus. For some years following its discovery, B19 was not associated with any defined clinical syndrome; although a high titre viraemia was often noted in infected individuals they were largely asymptomatic. In 1980 the causal association between B19 infection and aplastic crisis in chronic haemolytic anaemia began to emerge with the discovery of B19 as the agent responsible for aplastic crisis in sickle cell anaemia. This fulfilled the expectation of a disease of tissue comprising a large proportion of dividing cells, namely the erythropoietic elements of the bone marrow, anticipated in autonomous parvovirus infection where viral replication is confined to dividing cells. More recently, erythema infectiosum, an illness sharing many of the clinical features of rubella, has been found to be the common result of B19 infection, although a spectrum of disease is now emerging. Much effort is currently directed toward the elucidation of the effects of maternal B19 infection on the developing fetus.

Pruritus in parvovirus infection

An outbreak of slapped cheek syndrome (erythema infectiosum) occurred in Chepstow between March and June 1986. About 50 children with the illness were seen in one general practice. During the same period five women in the practice developed arthritis associated with human parvovirus infection and four of them suffered marked pruritus. It is suggested that if pruritus is a feature in any patient with an acute onset arthritis, parvovirus infection should be considered as a possible cause.

Serological study of rubella-like illnesses

We investigated 627 patients who within a period of 2 1/2 years had had a rubelliform rash and/or symptoms of arthritis and arthralgia. Sera from these patients were investigated for evidence of rubella, human parvovirus B19 (HPV), and measles infection with methods to detect specific IgM and IgG antibodies. Complement fixation tests were used to screen for a wide range of other infectious agents. We detected 229 cases of rubella, 43 cases of HPV infection, 7 cases of measles, and 9 cases of infection by various other aetiological agents. This left a large proportion of rubelliform rashes, 54% (339 cases), whose aetiology was unknown. This study confirmed that the diagnosis of rubella on clinical grounds alone is unreliable. Many (6.8%) of the rashes in the study were due to HPV infection, and the seasonal incidence was the same as for rubella. There was considerable overlap between the features of rubella and HPV infections, although in adults arthralgia occurred more frequently in HPV infections than in rubella. In all cases HPV infection was self-limiting, although, as in rubella, symptoms can be prolonged and one adult's disease lasted almost 9 months. Purpura was noted in only one patient with HPV infection. In this study three patients had HPV infection during pregnancy. Two patients spontaneously aborted one month later. The third patient progressed to full term and delivered a healthy baby.

B19 virus--a pathogenic human parvovirus

B19 virus is the first human virus to be shown to be a member of the parvovirus genus. This review is concerned with the diseases associated with B19 virus, their nature, pathogenesis and diagnosis. The virus was discovered by chance in blood donors but has been shown to be a common infection of childhood. Infection may be asymptomatic or associated with mild, non-specific symptoms. The most common specific clinical manifestation is an erythematous rash illness which often has the classical features of erythema infectiosum. Often, however, it is described simply as rubelliform and only laboratory tests can distinguish B19 and rubella virus infections. Joint involvement is the most common complication of B19 virus infection occurring especially in adult females. It often involves the joints of the hands and wrists, clears rapidly in most patients but may persist for months or years in a few. B19 virus is also the principle cause of the transient aplastic crisis which complicates chronic haemolytic anaemia. This has been demonstrated repeatedly in sickle cell anaemia and hereditary spherocytosis and in individual cases of other haemolytic anaemias. The pathogenesis of the aplastic crisis is related to the ability of B19 virus to infect and damage early erythroid progenitor cells. Volunteer studies in normal individuals have demonstrated that this is a regular event occurring about a week after infection via the respiratory tract. Rash illness and joint involvement occur 7 to 10 days later and are presumably immune mediated. Diagnosis of B19 virus infection can be achieved by detection of the viraemia (aplastic crisis) or by detection of virus specific IgM antibody (all diseases).(ABSTRACT TRUNCATED AT 250 WORDS)

Human parvovirus infection in pregnancy and hydrops fetalis

Human parvovirus is the causative agent of erythema infectiosum, a mild epidemic illness. In a recent outbreak in northeast Scotland, six women had serologic evidence of having contracted human parvovirus infection during pregnancy. Two of the women had midtrimester abortions, and both abortuses were grossly hydropic with anemia. They had similar microscopical histopathological features--a pronounced leukoerythroblastic reaction, hepatitis, excessive iron pigment in the liver, and eosinophilic changes in the hematopoietic cell nuclei. Dot hybridization with radiolabeled human parvovirus DNA probes revealed viral DNA in several tissues from both fetuses, indicating that they had been infected by the virus in utero. The remaining four women had uncomplicated pregnancies and delivered apparently healthy babies, none of whom had human parvovirus-specific IgM antibody at delivery. We conclude that this common virus may pose a serious risk to the fetus after maternal infection.