Persistent B19 parvovirus infection in patients infected with human immunodeficiency virus type 1 (HIV-1): a treatable cause of anemia in AIDS

Multiple primer pairs for polymerase chain reaction (PCR) amplification of human parvovirus B19 DNA

Human parvovirus B19 is the etiologic agent of erythema infectiosum and transient aplastic crisis in patients with hemolytic anemias and has been associated with fetal death, arthritis, and chronic anemia. Acute B19 infection is best diagnosed by detection of IgM antibodies, whereas the diagnosis of chronic infection often requires the sensitivity of PCR to demonstrate presence of virus over time. To improve our ability to detect B19 DNA by polymerase chain reaction (PCR), we evaluated 19 primers combined into 16 different primer pairs for their ability to detect temporally and geographically diverse B19 isolates. All 16 pairs reacted with all isolates tested but with different sensitivity. Sequence analysis showed few nucleotide changes compared with published sequences. These changes did not explain observed differences in sensitivity between primer pairs. The most sensitive primer pairs detected 350 to 3500 DNA copies after 35 cycles. A second amplification cycle with nested primers improved the sensitivity 100-fold. These 16 primer pairs provide the diagnostic virologist with multiple options for B19 PCR assays.

Persistent human parvovirus B19 infection following an acute infection with meningitis in an immunocompetent patient

A case in which parvovirus B19 infection persisted over a prolonged period of time in the blood of an immunocompetent patient following an acute infection with meningitis is reported. Using a nested polymerase chain reaction assay the viral genome was detected in cerebrospinal fluid as well as in blood at the time of overt disease and in consecutive blood samples collected for up to nine months.

Use of recombinant human parvovirus B19 antigens in serological assays

AIMS--To compare the sensitivity, specificity, and practicality of recombinant proteins in serological tests for the detection of human parvovirus B19 IgG and IgM. METHODS--Indirect enzyme linked immunosorbent assays using B19 structural proteins expressed in Escherichia coli were developed for the detection of B19 specific IgG and IgM (rELISA-G and rELISA-M). Cells infected with baculovirus expressing B19 structural proteins were also used in an indirect immunofluorescence assay for IgG and IgM antibodies (IFA-G and IFA-M). Antibody capture radioimmunoassays for IgG and IgM (GACRIA and MACRIA) were used as comparative assays. RESULTS--Twenty nine pools of intravenous immunoglobulin were clearly positive for B19 IgG by rELISA-G and contained low IgG titres by GACRIA. From 113 samples tested by all methods, sensitivities of 92% (77/84) and 97% (68/70) were obtained for ELISA and immunofluorescence, respectively, when compared with GACRIA. One hundred and sixteen samples from patients presenting with rash or arthralgia were compared by MACRIA, rELISA-M, and IFA-M. Sensitivities of both recombinant tests were more than 95%. Despite pretreatment to remove IgG or rheumatoid factor, false positive results were a problem in the rELISA-M but were not seen with the IFA-M. CONCLUSIONS--The limited supply of native antigen has severely restricted the wide application of serology for parvovirus B19. The use of recombinant antigens permitted the introduction of local screening tests which had many advantages, including quicker results and relief of the burden on the Reference Laboratory. The use of rELISA-M for sensitivity and IFA-M for specificity and confirmation proved a useful and practical combination for diagnosis of recent infection with B19, and rELISA-G allowed the immune response to be determined in selected populations.

Electron microscopic identification of parvovirus virions in erythroid and granulocytic-line cells in a patient with human parvovirus B19 induced pancytopenia

In this short report we describe a patient with human parvovirus B19 (HPV B19)-induced transient pancytopenia. Parvovirus virions were seen by electron microscopy in both erythroid and granulocytic precursors. Erythroid cells are not the only targets in these cases. We draw attention to this disorder so that physicians involved with hematological disorders and transplantation be more aware of this infection.

Human parvovirus B19 infections: routine diagnosis by a new nested polymerase chain reaction assay

A nested primer PCR assay was developed to detect human parvovirus B19 in various clinical specimens in a routine diagnostic laboratory. Under optimized conditions the highly specific assay had a sensitivity of less than 10 genome units. For practical reasons, however, this sensitivity was adjusted to 10-100 virus genomes in diagnostic applications. Using clinical specimens from 200 patients with suspected B19 infection, nested PCR was shown to have important diagnostic advantages over the detection of B19 specific antibodies. The data suggest that on the basis of serological data as obtained with currently available test systems a considerable proportion of B19 infections would be misdiagnosed. Examples for the usefulness of the PCR assay in routine diagnosis are given.

Neutralizing linear epitopes of B19 parvovirus cluster in the VP1 unique and VP1-VP2 junction regions

Presentation of linear epitopes of the B19 parvovirus capsid proteins as peptides might be a useful vaccine strategy. We produced overlapping fusion proteins to span the viral capsid sequence, inoculated rabbits, and determined whether the resulting antisera contained antibodies that neutralized the ability of the virus to infect human erythroid progenitor cells. Antibodies that bound to virus in an enzyme-linked immunosorbent assay were present in antisera raised against 10 of 11 peptides; strongest activity was found for antisera against the carboxyl-terminal half of the major capsid protein. However, strong neutralizing activity was elicited in animals immunized with peptides from the amino-terminal portion of the unique region of the minor capsid protein and peptides containing the sequence of the junction region between the minor and major capsid proteins. The development of neutralizing activity in animals was elicited most rapidly with the fusion peptide from the first quarter of the unique region. A 20-amino-acid region of the unique region of the minor capsid protein was shown to contain a neutralizing epitope. Multiple antigenic peptides, based on the sequence of the unique region and produced by covalent linkage through a polylysine backbone, elicited strong neutralizing antibody responses. Synthetic peptides and fusion proteins containing small regions of the unique portion of the minor capsid protein might be useful as immunogens in a human vaccine against B19 parvovirus.

Nested polymerase chain reaction assay for the detection of B19 parvovirus DNA in human immunodeficiency virus patients

Persistent B19 parvovirus infection has been recognized in immunocompromised patients, often occurring with a low-titer viremia. In this study, nested polymerase chain reaction (PCR) for the detection of B19 parvovirus DNA was carried out on the sera of 49 human immunodeficiency virus (HIV)-1-seropositive patients, negative for the detection of B19 DNA at dot blot hybridization assay and with different values of serum anti-B19 IgM (27 patients proved positive and 22 negative). Of the 49 HIV-seropositive samples tested by nested PCR, seven were positive for the detection of B19 DNA. All seven belonged to the group of subjects seropositive for specific anti-B19 IgM. The study shows that, in the presence of specific B19 IgM, circulating virus may still be present but can be detected only by PCR. In that B19 infection can occur with low-titer viremia in immunocompromised patients, PCR may be the only method for virus detection.

Association between immune activation, changes of iron metabolism and anaemia in patients with HIV infection

The pathogenesis of anaemia associated with human immunodeficiency virus infection is still far from being understood. It cannot be explained by direct effects of the virus on the haematopoietic system. Recent data suggest a role for immune activation. In a cross-sectional study we compared blood cell counts, haemoglobin and erythropoietin levels of 63 HIV-seropositive individuals with immune activation markers (interferon-gamma, serum and urine neopterin, and beta 2-microglobulin) and with parameters or iron metabolism (serum iron, transferrin, free iron binding capacity, ferritin). We found significant correlations between the concentrations of haemoglobin and the immune activation markers and erythropoietin concentrations. Additional significant correlations existed between the parameters of iron metabolism and haemoglobin levels, and ferritin correlated inversely with transferrin. In sum, low haemoglobin levels in patients were associated with enhanced cellular immune activation, as seen by increased interferon-gamma, neopterin and beta 2-microglobulin, and with changes of iron metabolism: low haemoglobin was associated with low transferrin and free iron binding capacity and high ferritin levels. Endogenous release of cytokines such as interferon-gamma-inhibiting erythropoiesis may be one underlying cause of anaemia in these patients.

Successful replication of parvovirus B19 in the human megakaryocytic leukemia cell line MB-02

The pathogenic human parvovirus B19 has been shown to undergo productive replication in the erythroid lineage in primary normal human hematopoietic progenitor cells. However, none of the established erythroleukemia cell lines has allowed B19 virus replication in vitro. The remarkable erythroid tissue tropism of B19 virus was evaluated with a human megakaryocytic leukemia cell line, MB-02, which is dependent on the growth factor granulocyte-macrophage colony-stimulating factor but can be induced to undergo erythroid differentiation following treatment with erythropoietin (Epo). Whereas these cells did not support B19 virus DNA replication in the presence of granulocyte-macrophage colony-stimulating factor alone, active viral DNA replication was observed if the cells were exposed to Epo for 5 to 10 days prior to B19 virus infection, as detected by the presence of the characteristic B19 virus DNA replicative intermediates on Southern blots. No replication occurred if the cells were treated with Epo for 3 days or less. In addition, complete expression of the B19 virus genome also occurred in Epo-treated MB-02 cells, as detected by Northern blot analysis. B19 progeny virions were released into culture supernatants that were biologically active in secondary infection of normal human bone marrow cells. The availability of the only homogeneous permanent cell line in which induction of erythroid differentiation leads to a permissive state for B19 virus replication in vitro promises to yield new and useful information on the molecular basis of the erythroid tissue tropism as well as parvovirus B19-induced pathogenesis.

[Viral risks associated with blood transfusion]

The presence of viruses in blood cells or plasma from asymptomatic donors is the major risk of transmitting an infectious agent through blood transfusion. The main viruses involved are hepatitis viruses and retroviruses. The risk of transmitting hepatitis B virus (HBV) and hepatitis C virus (HCV) has been progressively and efficiently reduced in the last years by the successive introduction of hepatitis B surface antigen (HBsAg) screening, elevated serum alanine aminotransferase (ALT), antibody to hepatitis B core (HBc Ab), and more recently antibody to hepatitis C virus (HCV Ab). The risk of transmitting human retroviruses like human immunodeficiency virus (HIV) and human T-cell leukemia/lymphoma virus (HTLV) has also been reduced drastically thanks to screening for corresponding antibodies. However, except for HBs Ag screening, the immunoassays used for HCV, HIV, or HTLV only detect antibodies. Therefore, although they are infectious, a few blood units may be not discarded. The efficacy of preventive measures depends on the incubation time, the infectivity during this silent phase, and the sensitivity of screening procedures. Human cytomegalovirus (HCMV) and parvovirus B 19 are responsible for common infections. Consequently, 30% to more than 50% adults have serologic evidence of past infection. However, both viruses may cause severe primo-infections in some circumstances, especially in pregnant women or immunodeficient individuals.

Immunophenotyping of fetal haemopoietic cells permissive for human parvovirus B19 replication in vitro

Human parvovirus B19 is known to inhibit erythroid colony formation in vitro, but the precise stage of differentiation at which erythroid precursors become capable of supporting viral replication has not been accurately determined. In order to address this issue, haemopoietic cells derived from first trimester fetal liver were cultured in medium containing B19 antigen-positive serum. Infected cells were phenotyped by combining immunohistology for cell-type specific antigens with non-isotopic in situ hybridization for B19 nucleic acid. Strong nuclear hybridization signal was detected as early as 8 h after infection in erythroid precursors labelling with antibodies to glycophorin A, glycophorin C, CD43, CD36 and HLA-ABC (pronormoblast or normoblast phenotype). Giant erythroid precursors labelling with the same five antibodies were a pathognomonic feature of infected cultures, but contained relatively little B19 nucleic acid. Hybridization signal was not detected in progenitor cells of more primitive erythroid phenotype or in nuclei of cells of other lineages, though B19 DNA was occasionally localized within the cytoplasm of macrophages. Double-labelling with antibody Ki-67 confirmed that proliferating cells were targets for B19 infection. Co-detection of cell-type specific antigens and viral nucleic acid is a powerful tool for investigating host cell specificity, and suggests that proliferating late erythroid precursors are the only haemopoietic cells fully permissive for B19 infection.

Applications of intravenous immunoglobulin in haematology

Intravenous immunoglobulin (IVIgG) has many potential applications in haematology both as antibody replacement therapy and as an immune-modulater in autoimmune disorders. Antibody replacement appears to be of value in the prophylaxis of infection in low-grade B-cell malignancies, in bone marrow transplant recipients and in children with AIDS, although optimal treatment strategies have not been assessed and determining which patients are likely to derive greatest benefit has been problematic. IVIgG appears to be effective in the prevention or amelioration of CMV-related pathology if given frequently and has also dramatically improved the survival of patients with established interstitial pneumonia when used in combination with ganciclovir. Intriguingly, IVIgG appears to moderate the severity of GVHD in adult transplant recipients. IVIgG has short term efficacy in most patients with ITP but, as long term remissions are uncommon, it has become necessary to be more selective in the use of IVIgG in this disorder. The response to IVIgG in other immune-mediated cytopenias is similar with generally transient improvement but also with occasional spectacular cures. The treatment of the acquired haemophilias with IVIgG has yielded in vivo and vitro evidence to support the idiotype-antiidiotype theory of IVIgG immune-modulation and has also demonstrated significant differences in the sensitivity of coagulation factor autoantibodies and alloantibodies to IVIgG therapy. IVIgG has several roles in pregnancy related disorders, including the management of both mother and fetus in ITP during pregnancy, the antenatal and postnatal management of platelet alloimmunisation and also in the management of severe rhesus isoimmunisation. IVIgG is safe and well tolerated. The expense of this therapy should be balanced against the likely gains and the overall costs of alternative approaches.

Parvovirus B19 infection and bone marrow transplantation

Parvovirus B19 lytically infects erythroid progenitor cells and thereby causes cessation of erythropoiesis in infected individuals. Anemia develops only if red cell turnover is increased, as in patients with chronic hemolysis (transient aplastic crisis). In addition to transient marrow failure, B19 can cause chronic anemia and, rarely, pancytopenia in immunodeficient patients who are not able to mount an adequate immune response to clear the virus. Bone marrow transplantation, although causing significant immunosuppression, is rarely complicated by symptomatic B19 infection. This is probably due to effective passive immunotherapy by immunoglobulin infusions immediately after transplantation and early reconstitution of antibody responses after uncomplicated transplantation.

Unique region of the minor capsid protein of human parvovirus B19 is exposed on the virion surface

Capsids of the B19 parvovirus are composed of major (VP2; 58 kD) and minor (VP1; 83 kD) structural proteins. These proteins are identical except for a unique 226 amino acid region at the amino terminus of VP1. Previous immunization studies with recombinant empty capsids have demonstrated that the presence of VP1 was required to elicit virus-neutralizing antibody activity. However, to date, neutralizing epitopes have been identified only on VP2. Crystallographic studies of a related parvovirus (canine parvovirus) suggested the unique amino-terminal portion of VP1 assumed an internal position within the viral capsid. To determine the position of VP1 in both empty capsids and virions, we expressed a fusion protein containing the unique region of VP1. Antisera raised to this protein recognized recombinant empty capsids containing VP1 and VP2, but not those containing VP2 alone, in an enzyme-linked immunosorbent assay. The antisera immunoprecipitated both recombinant empty capsids and human plasma-derived virions, and agglutinated the latter as shown by immune electron microscopy. The sera contained potent neutralizing activity for virus infectivity in vitro. These data indicate that a portion of the amino terminus of VP1 is located on the virion surface, and that this region contains intrinsic neutralizing determinants. The external location of the VP1-specific tail may provide a site for engineered heterologous epitope presentation in novel recombinant vaccines.

Human immunodeficiency virus associated anemia

Anemia in HIV-infected patients is often overshadowed by other disorders associated with this viral disease, but it can markedly contribute to morbidity and limit antiviral therapy. Evaluation of this patient population is difficult because of the probability of a multifactorial etiology and spurious laboratory indicators. Ineffective or reduced erythropoiesis is a hallmark of most anemic HIV-infected patients, leading to usage and continuing research of recombinant hematopoietic cytokine therapy. The continuing explosion in knowledge of this virus, its effects, and treatment possibilities will, hopefully, lead to improved diagnostic and therapeutic options in approaching HIV-associated anemia.

Fibromyalgia syndrome in patients infected with human immunodeficiency virus. The Boston City Hospital Clinical AIDS Team

PURPOSE

To prospectively assess rheumatic manifestations of human immunodeficiency virus (HIV) disease in a municipal hospital clinic population in which intravenous drug use was the most common risk factor for HIV infection.

PATIENTS AND METHODS

Patients with documented HIV infection were evaluated for rheumatic disease using a standardized questionnaire and examination. Patients with fibromyalgia were compared with HIV-infected patients without fibromyalgia and with fibromyalgia patients without known risk factors for HIV infection.

RESULTS

Thirty-seven of 140 patients with HIV infection had muskuloskeletal symptoms. Three of these 37 patients had arthritis, but none had Reiter's syndrome or psoriatic arthritis. Thirty (81%) of 37 patients had chronic musculoskeletal symptoms (for 3 months or longer). Twenty of 30 patients with chronic musculoskeletal symptoms had polyarthralgia, and of those, 15 (75%) were found to have either definite or probable fibromyalgia syndrome. Therefore, fibromyalgia syndrome was found in 41% of HIV-infected patients with musculoskeletal symptoms and in approximately 11% of all HIV-infected patients. Fibromyalgia patients with HIV infection had a longer duration of HIV infection (p = 0.01) and more frequently reported past depressed mood (p = 0.001) than HIV-infected patients without fibromyalgia. Compared with 301 patients with fibromyalgia syndrome and no known risk behavior for HIV, known HIV-infected patients with fibromyalgia were more commonly male (p = 0.001) and reported current depressed mood more frequently (p = 0.0001).

CONCLUSION

Few patients with arthritis were noted among HIV-infected patients who had intravenous drug use as risk behavior. By comparison, fibromyalgia syndrome appeared to be a common cause of musculoskeletal symptoms in this patient population.

Viruses and the blood

Haematological syndromes attributed to viruses demonstrate geographical variations in incidence and great dependence on host factors. Severe haematological disease is the exception rather than the rule in dengue virus infection, and probably depends at least in part on the host immune response to the virus. The increased incidence of hepatitis-associated aplasia in east Asia may reflect distribution of an infectious agent, an environmental toxin, or genetic predisposition, but probably represents some combination of these factors. Agents with apparently universal distribution, such as parvovirus B19 and Epstein-Barr virus, are associated with bone marrow failure only in a very narrow range of hosts. These examples teach us that viral causes cannot automatically be excluded from the differential diagnosis of syndromes whose occurrence is rare or apparently sporadic. Further investigation of these syndromes should include more detailed characterization of host factors, particularly immunological characteristics, and possible infectious and toxic cofactors which are associated with morbidity.

Human parvovirus B19 infection in hemophiliacs first infused with two high-purity, virally attenuated factor VIII concentrates

Human parvovirus B19 can be transmitted by coagulation factor concentrates and is highly resistant to virucidal methods. To evaluate whether the additional removal of virus by chromatographic methods during the manufacture of high-purity concentrates reduces the risk of B19 transmission, we have prospectively evaluated the rate of anti-B19 seroconversion in two groups of susceptible (anti-B19 negative) hemophiliacs infused with high-purity, heated (pasteurized) or solvent-detergent-treated factor VIII concentrates. Both products infected a relatively high proportion of patients (nine of 20).

Replication and cytopathology of human parvovirus B19 in human umbilical cord blood erythroid progenitor cells

Human parvovirus B19 productively infected erythroid progenitor (EP) cells from umbilical cord blood, in vitro as shown by an increase of viral DNA in supernatant fluid assayed by dot blot hybridization and liquid scintillation counting. Progeny virus was released into the supernatant fluid of CD34+ EP cells which had been purified by immunomagnetic separation. This supernatant fluid was infectious for bone marrow cells. Erythroid bursts infected with virus showed characteristic cytopathic effect by electron microscopy consisting of cytoplasmic vacuolization, marginated chromatin, and nuclear inclusions of lattice or crystalline arrays. Cultures of umbilical cord blood EP cells may be useful for the propagation of parvovirus B19 serological testing reagents and the study of virus-host cell interactions.

Replication of parvovirus B19 in hematopoietic progenitor cells generated in vitro from normal human peripheral blood

Erythroid progenitor cells generated in vitro from peripheral human blood in the presence of interleukin-3 and erythropoietin were infected with human parvovirus B19. B19 virus DNA replication was highest 48 to 72 h after infection, and maximum levels of B19 virus proteins were detected in culture supernatants at 72 to 96 h after infection. B19 virus propagated in vitro was infectious. This cell culture system with peripheral blood cells facilitates studies in vitro of B19 virus replication.

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.

Diagnosis of human parvovirus B19 infections by polymerase chain reaction

The polymerase chain reaction (PCR) was used for detecting parvovirus B19 DNA in clinical specimens. A pair of oligonucleotide primers spanning the PstI-fragment of the B19 virus genome was used for PCR, and a PCR product of 727 bp was amplified. B19 virus DNA was detected in all sera (n = 26) of individuals in the incubation period and acute phase of infection. PCR was useful for detecting viral B19 DNA in amniotic fluid and fetal blood of hydropic fetuses, confirming fetal B19 virus infection.

Acute parvovirus B19 infection mimicking myelodysplastic syndrome of the bone marrow

A 36-year-old, previously healthy woman was referred to our institution with pancytopenia and splenomegaly for suspected acute leukemia. Bone marrow aspiration showed marked dysplastic changes, excess of blasts, and only spurious red blood cell precursors. Action was taken to prepare allogeneic bone marrow transplantation from an HLA identical sibling for myelodysplastic syndrome. Repeat cytological examination of the bone marrow revealed striking hyperplasia of the red cell line with presence of abnormal giant proerythroblasts. Acute parvovirus B19 infection was suspected and confirmed by detection of anti-B19 IgM and B19 DNA. The underlying disease for this transient aplastic crisis was a formerly unknown hereditary spherocytosis.

A second neutralizing epitope of B19 parvovirus implicates the spike region in the immune response

We used 18 monoclonal antibodies against B19 parvovirus to identify neutralizing epitopes on the viral capsid. Of the 18 antibodies, 9 had in vitro neutralizing activity in a bone marrow colony culture assay. The overlapping polypeptide fragments spanning the B19 structural proteins were produced in a pMAL-c Escherichia coli expression system and used to investigate the binding sites of the neutralizing antibodies. One of the nine neutralizing antibodies reacted with both VP1 and VP2 capsid proteins and a single polypeptide fragment on an immunoblot, identifying a linear neutralizing epitope between amino acids 57 and 77 of the VP2 capsid protein. Eight of nine neutralizing antibodies failed to react with either of the capsid proteins or any polypeptide fragments, despite reactivities with intact virions in a radioimmunoassay, suggesting that additional conformationally dependent neutralizing epitopes exist.

A rapid method of sample preparation for detection of DNA viruses in human serum by polymerase chain reaction

A rapid method of serum treatment is described that can be used for the detection of viral DNA by polymerase chain reaction (PCR). The key feature of the assay is inactivation of inhibitory serum factors by controlled heating of serum. This method avoids DNA extraction. It is very fast and limited sample handling decreases the chances of contamination by exogenous DNA. It has been successfully used for demonstration of parvovirus B19, hepatitis B virus, and human cytomegalovirus DNA in patient sera. Since pathological components in sera from patients with various diseases do not interfere in the assay, it can be used as a sensitive and safe screening assay for DNA viruses in a routine clinical setting.

Fibromyalgia and parvovirus infection

An infectious cause of fibromyalgia (FM) has been hypothesized based upon the observed similarity of this entity and chronic fatigue syndrome. Three patients developed symptoms of FM after documented episodes of acute parvovirus B19 infections. B19 antibody determinations were obtained approximately 1 month after the symptoms began; both IgM and IgG titers were positive at that time. All 3 patients met criteria for FM. Polysomnography performed on 2 of the patients revealed profound alpha-wave intrusion throughout nonrapid eye movement sleep. A more careful search for viral infections in FM patients whose symptoms appear following a "flu-like" illness appears warranted.

Human parvovirus B19 specific IgG, IgA, and IgM antibodies and DNA in serum specimens from persons with erythema infectiosum

To determine the diagnostic use of different markers of acute parvovirus B19 infection, serum specimens obtained from 128 persons with erythema infectiosum were tested for specific immunoglobulin G (IgG), IgA, and IgM antibodies by capture enzyme immunoassay (EIA) using Chinese hamster ovary (CHO) cell-expressed B19 antigen, and tested for circulating B19 DNA by polymerase chain reaction (PCR). A significant rise in specific IgG and IgA antibodies was detected in 87% and 77%, respectively, of persons from whom acute- and convalescent-phase serum specimens were available. Specific IgA antibodies were detected in single serum specimens from 90% of cases and were present in 22 (18%) of 120 persons from a control group without a history of recent exposure to B19. Specific IgM antibodies were detected in 97% of cases and one person (1%) from the control group. B19 DNA was detected in 94% of cases and was absent in 20 persons from the control group positive for both IgG and IgA antibodies. Serum specimens obtained between 4 and 6 months after onset of illness from six additional persons were also tested. All had specific IgG antibodies, four (67%) had IgA, five (83%) had IgM, and none had detectable B19 DNA. Our data indicate that 1) specific IgA antibodies are too persistent to be a useful indicator of recent B19 infection; 2) specific IgM antibodies are the most sensitive indicator of acute B19 infection in immunologically normal persons but can persist up to 6 months; and 3) B19 DNA can often be detected up to 2 months after onset of illness even in immunologically normal hosts and might be a useful adjunct test for diagnosis of acute B19 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.

Dermatologic therapy: 1990

This article reviews significant therapeutic advances that have been reported in the English-language literature during 1990. Readers should review the original article in full before attempting any new experimental or controversial therapy.

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.