Persistent parvovirus B19 infections in humans

Parvovirus B19 DNA and antibodies in Chinese plasma donors, plasma pools and plasma derivatives

BACKGROUND

Human parvovirus B19 (B19V) is a common contaminant found in plasma pools and plasma derivatives. Previous studies were mainly focused on limited aspects, further assessment of prevalence of B19V DNA and antibodies in plasma donors, the contamination of B19V in pooled plasma and plasma derivatives should be performed in China.

STUDY DESIGN AND METHODS

Individual plasma donors' samples from four provinces and pooled plasma from four Chinese blood product manufacturers were collected and screened using B19V DNA diagnostic kits between October 2018 and May 2020. The positive samples were investigated for the seroprevalence of B19V antibodies and subjected to sequence analysis and alignment for phylogenetic studies. Moreover, 11 plasma donors who were B19V DNA-positive at their first testing were also followed during the later donation period. Additionally, 400 plasma pools and 20 batches of plasma derivatives produced by pooled plasma with a viral load of B19V DNA exceeding 104IU/mL were also collected and tested for B19V DNA and antibodies.

OBJECTIVES

To comprehensively and systematically determine the frequency and viral load of B19V DNA in plasma donors, pooled plasma, and plasma derivatives from four Chinese blood product manufacturers.

RESULTS

A total of 17,187 plasma donors were analyzed and 44 (0.26%) specimens were found positive for B19V DNA. The quantitative DNA levels ranged from 1.01 × 101 to 5.09 × 1012 IU/mL. Forty-four DNA-positive specimens were also investigated for the seroprevalence of B19V antibodies, 75.0% and 2.3% of which were seropositive for B19V IgG and IgM antibodies, respectively. The phylogenic analyses showed that the prevalent genotypes in the four provinces' plasma donors belonged to B19V Genotype 1. Eleven individual plasma donors who were B19V DNA-positive at the first donation were then followed for a period, and in general, the DNA levels of B19V gradually decreased. Moreover, 64.8% (259/400) of the pooled plasma was contaminated by B19V, with concentrations of 1.05 × 100-3.36 × 109IU/mL. Approximately 72.6% of the DNA-positive plasma pools were only moderately contaminated (<104 IU/mL), while 27.4% contained >104 IU/mL. Twenty batches of plasma derivatives produced by pooled plasma with a viral load of B19V DNA exceeding 104IU/mL were also tested. B19V was detected in 5/5 PCC samples and 5/5 factor VIII samples but was not found in the intravenous immune globulin and albumin samples.

CONCLUSION

The contamination of B19V in pooled plasma and plasma-derived clotting factor concentrates is serious. Whether B19V nucleic acid testing (NAT) screening of plasma and plasma derivatives is launched in China, blood product manufacturers should spontaneously perform B19V NAT screening in plasma donors and mini-pool plasma. These measures can ensure that samples with high titer B19V DNA are discarded in order to prevent and control this transfusion transmitted virus.

Surveillance of densoviruses and mesomycetozoans inhabiting grossly normal tissues of three Aotearoa New Zealand asteroid species

Asteroid wasting events and mass mortality have occurred for over a century. We currently lack a fundamental understanding of the microbial ecology of asteroid disease, with disease investigations hindered by sparse information about the microorganisms associated with grossly normal specimens. We surveilled viruses and protists associated with grossly normal specimens of three asteroid species (Patiriella regularis, Stichaster australis, Coscinasterias muricata) on the North Island / Te Ika-a-Māui, Aotearoa New Zealand, using metagenomes prepared from virus and ribosome-sized material. We discovered several densovirus-like genome fragments in our RNA and DNA metagenomic libraries. Subsequent survey of their prevalence within populations by quantitative PCR (qPCR) demonstrated their occurrence in only a few (13%) specimens (n = 36). Survey of large and small subunit rRNAs in metagenomes revealed the presence of a mesomycete (most closely matching Ichthyosporea sp.). Survey of large subunit prevalence and load by qPCR revealed that it is widely detectable (80%) and present predominately in body wall tissues across all 3 species of asteroid. Our results raise interesting questions about the roles of these microbiome constituents in host ecology and pathogenesis under changing ocean conditions.

A cross-sectional study on risk factors for infection with Parvovirus B19 and the association with anaemia in a febrile paediatric population in Ghana

Parvovirus B19 (B19V) occurs globally and can cause severe anaemia. The role of co-infections with Plasmodium falciparum (P. falciparum) has been controversially discussed. The study aimed to determine prevalence and severity of B19V infection, and the effect of co-infections on the risk for anaemia. Between November 2013 and April 2015 a total of 1186 hospital visits of children with fever admitted to a hospital in Ghana were recorded. Malaria, B19V and additional diagnostics for fever causes were performed. Recent B19V infection was defined as PCR and/or IgM positivity. Risk factors for a B19V infection and for anaemia were analysed. The prevalence of anaemia was compared between children with/without B19V infection, stratified for the presence of malaria. B19V IgM/PCR was positive in 6.4% (n = 76; 40 IgM + , 30 PCR + , 6 IgM + and PCR +). Among the B19V cases 60.5% had a simultaneous P. falciparum infection. B19V IgM positivity but not PCR positivity was associated with moderate-severe anaemia (OR = 2.6; 95%-CI: 1.3-5.3; P < 0.01 vs. OR = 0.9; 95%-CI: 0.4-1.8; P = 0.70). P. falciparum and IgM positive B19V infection were independent risk factors for anaemia with no evidence of effect modification. Our data show a significant association between B19V infection, defined as IgM but not PCR positivity, and moderate-severe anaemia. A multiplicative effect of B19V and P. falciparum infection was not found.

High-sensitivity virus and mycoplasma screening test reveals high prevalence of parvovirus B19 infection in human synovial tissues and bone marrow

Background

Latent microorganism infection is a safety concern for the clinical application of mesenchymal stem cells (MSCs). The aim of this study is to investigate the frequencies and sensitivities of the latent virus and mycoplasma infections in synovium, bone marrow, peripheral blood cells, and blood plasma and cultured synovial MSCs.

Methods

Total DNA and RNA of the synovium (n = 124), bone marrow (n = 123), peripheral blood cells (n = 121), plasma (n = 121), and 14-day cultured synovial MSCs (n = 63) were collected from patients who underwent total knee arthroplasty or anterior ligament reconstruction after written informed consents were obtained. The multiplex polymerase chain reaction (PCR) primers were designed to quantitatively measure the representative genomes of 13 DNA viruses, 6 RNA viruses, and 9 mycoplasmas. Multi-spliced mRNA detection and virus spike test were also performed to demonstrate the sensitivity of synovial MSCs to the candidate pathogens.

Results

In synovium and bone marrow, the positive rates of parvovirus B19 genome were significantly higher than in peripheral blood cells (18.7% and 22% vs. 0.8%, respectively). Multi-alignment analysis of amplified and sequenced viral target genes showed the proximity of the parvovirus B19 gene from different tissue in the same patients. Synovial MSCs cultured for 14 days were positive for virus infection only in two patients (2/62 = 3%). Parvovirus B19 multi-spliced mRNAs were not detected in these two samples. Virus spike test demonstrated the sensitivity of synovial MSCs to herpes simplex virus (HSV)1 and cytomegalovirus (CMV), but not to parvovirus B19.

Conclusion

This study revealed a relatively high incidence of latent parvovirus B19 in synovium and bone marrow tissue.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0811-7) contains supplementary material, which is available to authorized users.

Persistent and Prolonged Parvovirus B19 Viremia in a Pediatric Patient With Acute Lymphoblastic Leukemia

Parvovirus B19 is a small single-stranded DNA virus of the Parvoviridae family. Depending on host factors, it may produce a wide array of clinical disease states. Disease severity can range from self-limited to severe, requiring significant supportive care. Immunocompromised patients are generally affected more severely but rarely develop prolonged and persistent infections. Here, we describe a patient who was diagnosed with parvovirus during maintenance therapy for acute lymphoblastic leukemia and required therapy with intravenous immunoglobulin; the patient remained parvovirus positive according to a polymerase chain reaction testing but had no clinical symptoms for 27 months off chemotherapy.

Frequency and genotype of human parvovirus B19 among Iranian patients infected with HIV

The human parvovirus B19 (B19) usually causes a subclinical infection in immunocompetent individuals. Whereas immunocompromised individuals such as patients infected with HIV are at risk of persistent anemia due to B19 infection. Only few studies have been carried out on distribution and molecular epidemiology of B19 in Iran. We aimed to determine the frequency and genotype of B19 among Iranian patients infected with HIV. We conducted a survey on 99 HIV patients and 64 healthy controls. IgG and IgM antibodies against B19 were detected by ELISA and B19 DNA was assessed by nested PCR. PCR products were subjected to direct sequencing and classified after phylogenetic analysis. The prevalence of B19 immunoglobulin was 11.1% for IgG and 1% for IgM. B19 DNA was detected in 13.1% of cases. The prevalence of B19 IgG, IgM, and DNA in control group was 25%, 1.6%, and 9.4%, respectively. B19 IgG was significantly lower in HIV group than in normal controls. There was no significant difference regarding anemia between cases and controls. All sequenced B19 isolates belonged to genotype 1A with low genetic diversity. Our findings indicated that in the HAART era, the importance of B19 infections in HIV patients may be limited whereas persistent B19 viremia in the circulation of healthy controls raises a potential concern in blood donations.

Status of immunity against PVB19 in HIV-infected patients according to CD4(+) cell count, and antiretroviral therapy regimen groups

Background:

Human Parvovirus B19 (PVB19) is among the aetiology of aplastic crisis in human immunodeficiency virus (HIV)-infected patients. Several studies have indicated the importance of an infection agent in bringing about complications in immuno-compromised patients. The current study aims to determine the seroprevalence of IgM and IgG antibodies to PVB19 among HIV-positive patients and its association with clinical and epidemiological factors.

Materials and Methods:

In a case control study, 90 HIV-positive patients were compared with 90 sex and age matched healthy controls in terms of anti-PVB19 IgG and IgM along with other primary clinical and laboratory features.

Results:

The overall prevalence of positive anti-PVB19 IgG among HIV patients and controls were 81.1% and 28.9%, respectively (P < 0.001). None of the subjects showed positive results for anti-PVB19 IgM. Patients with CD4⁺ cell count <200 showed higher seroprevalence of positive anti-PVB19 IgG which did not reach statistically significant. However, anti-PVB19 IgG seropositivity differed significantly between HIV patients on different regimens of antiretroviral therapy (ART) (P < 0.05).

Conclusion:

Immunity against PVB19 is more prevalent among HIV-positive patients compared to healthy controls. However, positive HIV status is not associated with acute PVB19 infection. The presence of anti-PVB19 IgG does not necessarily protect the body from further complications like anaemia. Given the results of the study, AIDS patients are recommended to undergo screening for parvovirus antibody in order to prevent complications like aplastic anaemia.

Human immunodeficiency virus/human parvovirus B19 co-infection in blood donors and AIDS patients in Sichuan, China

BACKGROUND

Human parvovirus B19 (B19) is a common pathogen which causes a variety of diseases. Persistent B19 infection is related to the degree of host immunodeficiency in patients with human immunodeficiency virus (HIV) infection. However, the existence, loading, virus evolution and distribution of B19 in Chinese HIV-positive patients have not been determined.

MATERIALS AND METHODS

We investigated 573 HIV-positive blood donors and AIDS patients in Sichuan, China in the last two decades. Bl9-specific serology and quantitative polymerase chain reaction were used to determine the prevalence of B19/HIV co-infection. Viral genome fragments were subjected to phylogeny and haplotype analysis.

RESULTS

B19 genomic DNA was found in 26 of 573 (4.5%) HIV-positive individuals, a higher prevalence than in blood donors. DNA levels ranged from 5.3×10(2)-1.1×10(5) copies/mL. The seroprevalence of IgG was significantly lower in HIV-positive samples than in HIV-negative blood donors, indicating deficient production of B19-specific IgG in the former. The B19 isolates were genotype-1 subtype B19-1A which formed a monophyletic group; seven distinct haplotypes were discovered with 60% of the B19/HIV co-infected variants sharing one central haplotype.

DISCUSSION

This study on the prevalence, phylogeny and distribution of human parvovirus B19 in Sichuan, China, demonstrates the persistence of B19 in the circulation of both immunocompetent and immunocompromised subjects, with implications for blood safety.

A cluster of parvovirus B19 infections in renal transplant recipients: a prospective case series and review of the literature

Up to 9% of renal transplant recipients have severe multifactorial erythropoietin-resistant anemia. Human parvovirus B19 (PVB19) infection can cause severe anemia and is likely underreported. Sparse information on epidemiology and management in this population exists. To address these issues, after our first index case, we modified our clinical practice to prospectively screen patients with persistent hemoglobin (Hb) <10 mg/dL for PVB19 infection after excluding common causes of anemia including erythropoietin resistance. Potentially infected patients were further evaluated by serology, qualitative polymerase chain reaction (quPCR) and bone marrow biopsy (BMB) for cytomegalovirus, Epstein-Barr virus, PVB19 and other etiologies. Over 3 months, 212 kidney recipients visited outpatient clinics. Of 52 recipients with anemia, 8 had an Hb <10 mg/dL with erythropoietin resistance and were screened for PVB19 infection. Three cases had PVB19 infection by quPCR and often-inconclusive serology/BMB results. Cases had immunosuppression reduced and received IVIG (0.5 gm/kg x 4 doses) with recovery from anemia, viral clearance in two cases and one recurrence. PVB19-mediated anemia occurred in up to three out of eight (38%) screened kidney recipients with Hb <10 mg/dL resistant to erythrypoietin. We recommend prospective risk stratification for this population, high indices of suspicion using at least qualitative techniques for diagnosis and treatment goal for viral eradication.

Exposure of hematologic patients to parvovirus B19 as a contaminant of blood cell preparations and blood products

BACKGROUND

Patients with hematologic malignancies often require blood products, and parvovirus B19 is known to be transmitted by this route. Primary infection with parvovirus B19 shows a wide variety of disease manifestation. In immunocompromised patients, symptoms are severe and viral clearance is delayed or missing.

STUDY DESIGN AND METHODS

A total of 2123 blood products given to all patients of a hematologic ward over a period of 6 months were retrospectively examined for the presence of parvovirus B19 DNA by an in-house real-time polymerase chain reaction (PCR; TaqMan). Patients who had received B19 DNA-positive blood products were further investigated serologically and by PCR for the presence of parvovirus B19 antibodies and DNA.

RESULTS

Twenty-one (1%) of 2123 blood products tested positive for the presence of B19 DNA (2% of pooled products, 0.7% of single-donor products, and 17.6% of allogeneic peripheral blood progenitor cells), the median viral load was 700 genome equivalents per mL. During the study period, 114 patients were treated on the ward, and 14 (12%) of them received B19 DNA-positive blood components. None of them developed symptoms of an acute B19 infection, although one had a short low-level viremia.

CONCLUSIONS

Although B19 DNA was detected in 1 percent of blood products given to hematologic patients, the exposure of 12 percent of patients did not result in symptomatic infections.

Detection and differentiation of human parvovirus variants by commercial quantitative real-time PCR tests

Parvovirus B19 causes a variety of diseases in humans, with outcomes ranging from asymptomatic to severe, such as chronic anemia in immunocompromised patients or fetal hydrops and death after maternal infection during pregnancy. The virus may be transmitted via plasma-derived products. According to the results of solvent-detergent safety studies, an upper limit of B19 DNA in plasma pools was recently defined. To restrict the input of B19 virus into production pools, a quantitative nucleic acid test is a prerequisite. We examined the suitability of the two commercial quantitative B19 PCR tests, LightCycler-Parvovirus B19 quantification kit (Roche Diagnostics) and RealArt Parvo B19 LC PCR (Artus) for detection, quantification, and differentiation of the three known B19 genotypes, including the newly described erythrovirus variants (genotypes 2 and 3). The former kit was highly sensitive for genotype 1 but was not suitable for detection of genotype 2 or one of two genotype 3 strains. The latter kit detected and differentiated all three genotypes, albeit with lower sensitivity for one of the genotype-3 strains. We furthermore assessed the prevalence of the three B19 virus genotypes in blood donors, by screening pooled plasma samples derived from 140,160 Finnish blood-donor units. None of the pools contained detectable levels of B19 virus genotypes 2 or 3. The origin, mode of transmission, and clinical significance of these genotypes are unknown and deserve further study. The RealArt Parvo B19 LC PCR is suitable for detection, quantification, and differentiation of all three B19 virus genotypes in molecular and clinical research.

Parvovirus B19 and the pathogenesis of anaemia

Human parvovirus B19 (B19) infection causes human bone marrow failure, by affecting erythroid-lineage cells which are well-known target cells for B19. The anaemia induced by B19 infection is of minor clinical significance in healthy children and adults, however, it becomes critical in those afflicted with haemolytic diseases. This condition is called transient aplastic crisis, and the pathogenesis is explained by the short life-span of red blood cells. Similarly, fetuses are thought to be severely affected by B19-intrauterine infection in the first and second trimester, as the half-life of red blood cells is apparently shorter than RBC at the bone marrow haematopoietic stage. On the other hand, B19 is also the causative agent of persistent anaemia in immunocompromised patients, transplant recipients and infants. The deficiencies of appropriate immune responses to B19 impair viral elimination in vivo, which results in enlargement of B19-infected erythroid-lineage cells. The B19-associated damage of erythroid lineage cells is due to cytotoxicity mediated by viral proteins. B19-infected erythroid-lineage cells show apoptotic features, which are thought to be induced by the non-structural protein, NS1, of B19. In addition, B19 infection induces cell cycle arrests at the G(1) and G(2) phases. The G(1) arrest is induced by NS1 expression prior to apoptosis induction in B19-infected cells, while the G(2) arrest is induced not only by infectious B19 but also by UV-inactivated B19, which lacks the ability to express NS1. In this review, we address the clinical manifestations and molecular mechanisms for B19-induced anaemia in humans and a mouse model, and of B19-induced cell cycle arrests in erythroid cells.

Recurrent high level parvovirus B19/genotype 2 viremia in a renal transplant recipient analyzed by real-time PCR for simultaneous detection of genotypes 1 to 3

Organ transplant recipients infected with parvovirus B19 frequently develop persistent viremia associated with chronic anemia and pure red cell aplasia. In this study, a male renal transplant recipient who had been infected with parvovirus B19/genotype 2 after renal transplantation at the age of 34 years is described. The patient was repeatedly treated with high dose intravenous immunoglobulin (IVIG) that resulted in the resolvement of symptoms but not in virus eradication. During an observation period of 33 months after transplantation three phases associated with high parvovirus B19 viremia were observed. Both the first and the second viremic phases were combined with severe anemia. Parvovirus B19 specific IgM-antibodies were initially detected at the beginning of the second phase in continually rising concentrations. Initially eradication of the virus by immunoglobulin therapy was reported after the first viremic phase [Liefeldt et al. (2002): Nephrol Dial Transplant 17:1840-1842]. Retrospectively this statement has to be corrected. It was based on the use of a qualitative PCR assay specific for parvovirus B19 genotype 1 associated with reduced sensitivity for detection of genotype 2. After sequence analysis of the viral DNA and adjustment of a real-time PCR assay (TaqMan) for quantitative detection of all three B19 virus genotypes analysis of consecutive serum samples allowed the demonstration of long lasting phases with reduced viral loads following IVIG-treatment. These results demonstrate that IVIG treatment of parvovirus B19-triggered anemia in transplant recipients offers an opportunity to resolve symptoms, but does not guarantee eradication of the virus. Since reactivation of parvovirus B19 infection can result in high virus load associated with the recurrence of symptoms repeated screening for viral DNA is recommended using the TaqMan system established for quantitative detection of all three genotypes of parvovirus B19.

B19 virus infection in renal transplant recipients

BACKGROUND

B19 virus infection with persistent anaemia has been reported in organ transplant recipients. Detection of B19 virus DNA in serum is the best direct marker of active infection.

OBJECTIVE

The present study evaluated the incidence and clinical role of active B19 virus infection in renal transplant recipients presenting with anaemia.

STUDY DESIGN

Forty-eight such recipients were investigated by nested PCR on serum samples. The controls were 21 recipients without anaemia. Active HCMV infection was also investigated as a marker of high immunosuppression.

RESULTS AND CONCLUSIONS

In 11/48 (23%) patients B19 virus DNA was demonstrated in serum versus only 1/21 (5%) of the controls. Ten of these 11 patients had already been seropositive at transplantation and active infection occurred in eight of them during the first 3 months after transplantation. The remaining patient experienced a primary infection 9 months after transplantation. Eight (73%) of these 11 patients displayed a concomitant HCMV infection and four (36%) showed increasing serum creatinine levels but none developed glomerulopathy; 3/11 (27%) recovered spontaneously from anaemia whereas 8/11 (73%) needed therapy. In conclusion, the relatively high occurrence (23%) of B19 virus infection in patients presenting with anaemia, suggests that it should be considered in the differential diagnosis of persistent anaemia in renal transplant recipients. Presence of the viral DNA should be assessed early from transplantation and the viral load should be monitored to follow persistent infection and better understand the relation between active infection and occurrence of anaemia, and to assess the efficacy of IVIG therapy and/or immunosuppression reduction in clearing the virus.

Chronic parvovirus B19 infection in a pediatric lung transplanted patient

In immunocompromised patients, clinical manifestations of human parvovirus B19 (PVB19) infection are mostly reported as acute or chronic hematological disorders. Recently, PVB19 infection has been associated with nonhematological symptoms. Four years after lung transplantation, a 9-year-old girl developed a severe anemia with reticulocytopenia requiring blood transfusion. PVB19 DNA was found by polymerase chain reaction in blood. Blood marrow aspiration revealed typical features of PVB19 infection. She was successfully treated with high dose of i.v. Ig. Then, she exhibited recurrent nonregenerative anemia requiring another course of i.v. Ig. PVB19 DNA has been persisted in blood with no specific immune response. At the same time, she suffered from several lung infection syndromes with no microorganism found except PVB19 DNA. Recurrent mild renal dysfunction was noticed with no other explanation than PVB19 infection. This report indicates that pediatric transplanted patients are at risk of chronic PVB19 infection, which can be associated with lung and/or renal disorders.

Efforts in minimizing risk of viral transmission through viral inactivation

The viral safety of blood and blood products has improved substantially over the last decade on account of the development of new viral screening and virucidal procedures. For nearly 15 years, virally inactivated blood derivatives, prepared by using advanced virucidal procedures, have amassed an extraordinary safety record with respect to hepatitis B and C and HIV. This record of safety has spawned the development of newer virucidal procedures designed to eliminate nonenveloped viruses from blood derivatives and viruses and other pathogens from blood components, including cellular components. Ongoing tests that include clinical studies will demonstrate how close we are to achieving a blood supply that is free of viruses, bacteria, and parasites.

Thrombotic microangiopathy associated with parvovirus B 19 infection after renal transplantation

Human parvovirus B19 is considered an etiologic agent of aplastic anemia in immunosuppressed patients. Microscopic vasculitis, with or without renal involvement, has recently been attributed to this viral infection in immunocompetent patients. This study describes four cases of thrombotic renal graft microangiopathy presumably secondary to B19 infection. Twelve to 50 days after transplantation, four patients presented a renal graft dysfunction with creatinine rising to 360 to 1088 micromol/L and requiring hemodialysis in three cases. Renal involvement appeared after a systemic illness characterized by fever, fatigue and arthralgia, aplastic anemia (hemoglobin ranged from 5.3 to 7.8 g/dl), and thrombocytopenia. A thrombotic microangiopathy was observed in the renal biopsies, and the parvovirus B19 genome was isolated by PCR from the specimens. All four patients also became IgM-positive for parvovirus. Three of the four renal biopsies taken at the time of transplantation (T0) from the same patients were found positive for the B19 genome. Graft function recovered, with resolution of the aplastic anemia, within 22 to 110 d. Twenty biopsies performed as routine controls or for suspected acute rejection and nine T0 biopsies of patients with no signs of B19 infection were used. The B19 genome was found in two of 20 posttransplant biopsies and in one of nine T0 biopsies. The temporal association between aplastic anemia and the onset of thrombotic graft microangiopathy, isolation of the viral genome in renal specimens, seroconversion, and endothelial tropism of the virus suggests that B19 could be the etiologic agent of thrombotic microangiopathy in these cases. The development of the disease after infection could depend on other detrimental cofactors, which make the patient more susceptible to microthrombi formation in the renal microvasculature. The renal graft could represent the route of B19 transmission.

Unusual bone marrow manifestations of parvovirus B19 infection in immunocompromised patients

Parvovirus B19 is responsible for a spectrum of disease in humans. The usual bone marrow findings in acute parvovirus infections are marked erythroid hypoplasia and occasional giant erythroblasts. Intranuclear inclusions in developing erythroid precursors are rarely described in children or adults with parvovirus infection, although abundant intranuclear inclusions are commonly observed in the placenta and other tissues in infected fetuses. In this study, 8 patients are reported in whom the first evidence of parvovirus infection was the recognition of numerous intranuclear inclusions in erythroid precursors on bone marrow biopsy sections. Six of the 8 patients had documented immunodeficiencies; 4 had acquired immune deficiency syndrome (AIDS), and 2 were on chemotherapy. Five of 7 patients were negative for immunoglobulin G (IgG) antiparvovirus antibodies, including all 4 with AIDS. Unlike the typical pattern in parvovirus infection, the bone marrow was hypercellular in most of the patients, and erythroid precursors were usually increased with the entire spectrum of normoblast maturation represented; abundant intranuclear inclusions were observed similar to the finding in fetuses. The inclusions were variably eosinophilic and compressed the chromatin against the nuclear membrane. In situ hybridization showed parvovirus B19 DNA in numerous erythroid precursors in all cases. The findings of erythroid maturation and abundant viral inclusions in these immunocompromised patients is consistent with the hypothesis that failure to produce effective IgG parvovirus neutralizing antibodies may lead to persistent infection through viral tolerance that allows erythroid development of infected cells past the pronormoblast stage. Identification of parvovirus inclusions in marrow biopsies and subsequent confirmation of infection by in situ hybridization can be important in the assessment of anemia in immunodeficient patients because serological studies for parvovirus B19 are frequently negative.

Clinical and laboratory evidence for a trilineage haematopoietic defect in patients with refractory Diamond-Blackfan anaemia

Diamond-Blackfan anaemia (DBA) is a constitutional pure red cell aplasia presenting in early childhood. In some patients, neutropenia and/or thrombocytopenia have also been observed during the course of the disease. We have followed 28 patients with steroid-refractory DBA for up to 13 years with serial peripheral blood counts and bone marrow (BM) aspirates and biopsies. In 21/28 (75%) patients, moderate to severe generalized BM hypoplasia developed, with overall cellularities ranging from 0% to 30%. Marrow hypoplasia correlated with the development of neutropenia (9/21; 43%) and/or thrombocytopenia (6/21; 29%) in many patients. No patient had either cytogenetic abnormalities or progressed to acute leukaemia, although one 13-year-old developed marked marrow fibrosis and trilineage dysplasia. We used the in vitro long-term culture-initiating cell (LTC-IC) assay to quantify multilineage, primitive haematopoietic progenitors in a representative subset of these patients. LTC-IC assays showed equivalent frequencies of cobblestone area-forming cells (CAFCs) with a mean of 5.42/10(5) cells +/- 1.9 SD and 6.13/10(5) cells +/- 2.6 SD in nine patients and six normal controls respectively. The average clonogenic cell output per LTC-IC, however, was significantly lower in DBA patients (mean 2.16 +/- 1.2 SD vs. 7. 36 +/- 2.7 SD in normal controls, P = 0.0008). Our results suggest that the underlying defect in patients with severe refractory DBA may not be limited to the erythroid lineage, as was evidenced by the development of pancytopenia, bone marrow hypoplasia and reduced clonogenic cell output in LTC-IC assays.

Mouse parvovirus infection potentiates allogeneic skin graft rejection and induces syngeneic graft rejection

BACKGROUND

The recently identified autonomous mouse parvovirus designated mouse parvovirus-1 (MPV-1) persists in adult BALB/c mice for at least 9 weeks, infects lymphoid tissues, interferes with the ability of cloned T cells to proliferate, and exhibits immunomodulatory properties. As a consequence of these findings, the present studies were undertaken to characterize further the inmunomodulatory effects of MPV-1 on T cell-mediated immune responses in vivo and in vitro.

METHODS

To evaluate the effect of MPV-1 infection on CD8+ T cell-mediated responses, BALB/c-H2dm2 mice were infected after transplantation of allogeneic BALB/c skin.

RESULTS

MPV-1 potentiated the rejection of allogeneic skin grafts. This potentiation was not a result of virus infecting the cellular or vascular component of the graft as determined by in situ hybridization, but was mediated by T cells. However, the proliferative capacity of alloantigen-reactive lymphocytes from graft-sensitized infected mice was diminished. MPV-1 also induced the rejection of syngeneic skin grafts, and T cells from these infected graft-sensitized mice lysed syngeneic P815 target cells.

CONCLUSIONS

These results suggest that MPV-1 infection of skin-grafted mice may disrupt normal mechanisms of peripheral tolerance and provide a unique model to study virus-induced autoimmunity.

Rheumatic manifestations of parvovirus B19 infection

Human parvovirus B19 is an emerging DNA virus. B19 infection is common and widespread. Major manifestations of B19 infection are transient aplastic crisis, erythema infectiosum, hydrops fetalis, acute and chronic rheumatoid-like arthropathy, and, in the immunocompromised host, chronic or recurrent bone marrow suppression. A number of less common manifestations of B19 infection include various rash illnesses, neuropathies, and acute fulminant liver failure. Of rheumatologic interest, B19 infection must be differentiated from early presentation of more classic erosive rheumatoid arthritis and, in some cases, systemic lupus erythematosus. It is unlikely that B19 plays a role in classic erosive rheumatoid arthritis, but understanding pathogenesis of B19 arthropathy may provide insights into the mechanisms by which rheumatoid arthritis develops. Evidence for persistence of B19 infection suggests that human parvovirus B19 infection may serve as a model for the study of virus-host interactions and the role of viruses in the pathogenesis of rheumatic diseases.

Human parvovirus B19 in bone marrows from adults with acquired immunodeficiency syndrome: a comparative study using in situ hybridization and immunohistochemistry

Human parvovirus B19, which infects and lyses erythroid precursors, can cause severe anemia in patients with immunodeficiency. The incidence of parvovirus infection in adult acquired immunodeficiency syndrome (AIDS) patients is unknown. Eighty-one archival formalin-fixed, paraffin-embedded (FFPE) bone marrow biopsies from 73 AIDS adults were immunostained with monoclonal R92F6 against B19 VP1 and VP2 capsid proteins using streptavidin peroxidase and streptavidin alkaline phosphatase techniques. In addition, the same tissues were hybridized in situ with a digoxigenin-labeled parvovirus B19 DNA probe. Five FFPE bone marrows, from 3 HIV-negative patients with positive immunoglobulin M (IgM) serology for parvovirus B19, and 1 parvovirus B19-infected fetal liver were positive controls. By immunoperoxidase, all tissues were negative with R92F6 except the fetal liver, which exhibited strong positivity predominantly in viral inclusions. With immunoalkaline phosphatase, all positive controls were immunoreactive with R92F6; however, the AIDS marrows were negative. With in situ hybridization (ISH), all positive controls and 7 of 81 (8.6%) of AIDS marrows were positive for B19 parvovirus DNA. We conclude that ISH is more sensitive than R92F6 immunohistochemistry in parvovirus B19 detection. A small but significant number of bone marrows from AIDS adults shows evidence of human parvovirus B19 infection.

Lymphoproliferative responses after infection with human parvovirus B19

Immunity after infection with the parvovirus B19 is assumed to be conferred by a humoral immune response with development of neutralizing antibody. In contrast, little is known about the nature of T-cell-mediated responses to parvovirus B19 infection in humans. We used recombinant proteins VP1, VP2, and NS1, as well as a recombinant VP1-specific amino-terminal sequence, to test the proliferative responses of peripheral blood mononuclear cells after infection of otherwise healthy individuals with parvovirus B19. These proteins were used as antigens for the stimulation of freshly isolated cells. The results show that a B19 virus-specific cellular immunity develops that is directed against the capsid proteins VP1 and VP2. We also demonstrate that viral determinants are presented to CD4+ T cells by HLA class II molecules.

The prevalence of antibody to parvovirus B19 in hemophiliacs and in the general population

The prevalence of antibodies to parvovirus B19 (B19) was measured in the sera of 566 hemophiliacs and 524 individuals of the general population by immunofluorescence assays, using antigen expressed by the baculovirus system. In the general population, anti-B19 IgG seroprevalence was found to continuously decline from 64 percent at birth to 0 percent in the age of 9-11 months and thereupon to increase to 61 percent in the age of 12 years. In younger adults and older people, IgG seroprevalence only slowly increased with age, reaching 77 percent in people aged 60 and above. In contrast, in hemophilic children treated exclusively with virally inactivated clotting factor concentrates, neither decrease nor increase of B19 IgG antibody was detectable and the overall seroprevalence was 92 percent. In the group of hemophiliacs older than 12 years and treated before 1984 with non-inactivated clotting factor concentrates, 98 percent showed antibody to B19. Anti-B19 IgM seroprevalence was significantly higher in hemophilic than in non-hemophilic individuals older than 12 years. Since it seems to be unlikely that the high seroprevalence in hemophiliacs is acquired by immunization with inactivated viral antigen, the results suggest that infection with B19 is transmitted by clotting factor concentrates, even if subjected to virucidal methods.

Comparative evaluation of virological and serological methods in prenatal diagnosis of parvovirus B19 fetal hydrops

Human parvovirus B19 infection in pregnancy represents a potential hazard to the fetus since fetal loss or fetal hydrops can occur. The risk of fetal loss due to transplacental B19 transmission has been evaluated in several studies using different diagnostic methods on maternal and fetal specimens. We analyzed the diagnostic value of virological and serological techniques on maternal serum, fetal cord blood, and amniotic fluid specimens obtained at the time of clinical diagnosis of fetal hydrops in 18 cases of B19 fetal hydrops. B19 DNA was detected by nested PCR, dot blot hybridization, and in situ hybridization assay. Anti-B19 immunoglobulin M and G antibodies were detected by immunoassays using recombinant B19 antigens. Our data suggest that for maternal sera, virological and serological methods have a complementary role in diagnosis, while for fetal specimens the in situ detection of B19 DNA in fetal cord blood is the most sensitive diagnostic system.

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.

Autoantibodies following parvovirus B19 infection

This study was undertaken to assess the incidence and significance of autoantibody production following B19 infection, 53 patients with acute B19 infection (positive for serum anti-B19 IgM) were studied; symptoms were rash and arthralgia (n = 26), rash (n = 7), arthralgia (n = 16), aplastic crisis (n = 3), and intrauterine death (n = 1). These patients were followed for 26-85 months (mean 57 months) and re-assessed for persistent symptoms, serum anti-B19 antibodies, and serum autoantibodies. At follow-up, 14 test and two control patients had one or more serum autoantibodies (anti-nuclear antibody, anti-smooth muscle antibody, gastric parietal cell antibody, anti-reticulin antibody, anti-mitochondrial antibody, rheumatoid factor) at a titre of > or = 40 (P = 0.004). Seven test patients and no control patients had serum autoantibody at a titre > or = 160. Of these seven test patients, only one had persistent symptoms. At follow-up assessment, this woman was 48-year-old, had persistent arthralgia for 4 years following acute B19 infection, rheumatoid factor at a titre of 160 (1920 IU/ml), and had been independently diagnosed as having rheumatoid arthritis. In conclusion, results of the present study showed that low titre autoantibody production was common following symptomatic B19 infection, however, while interesting from a virological standpoint, this finding may be of little significance for future development of autoimmune disease.

Automated detection of digoxigenin-labelled B19 parvovirus amplicons by a capture hybridization assay

An automated method to identify B19 amplicons, directly labelled with digoxigenin during amplification reaction was developed. The labelled amplicons were hybridized with a biotinylated B19 oligo-probe and captured on commercially available test tubes coated with streptavidin. The hybridized amplicons labelled with digoxigenin were detected using anti-digoxigenin Fab fragments conjugated to peroxidase and the colourimetric reaction automatically evaluated as an immunoenzymatic assay. Fifty serum samples were tested by the assay and the results were in accordance with those obtained by Southern blot analysis of amplified products. Due to the high sensitivity, specificity and reproducibility shown, the assay seems to be a practical and reliable test for the diagnosis of B19 infection and can be easily adapted to identify any digoxigenin-labelled amplified product of viral genomes.

Persistence of parvovirus B19 in synovial fluid and bone marrow

OBJECTIVES

To determine whether parvovirus B19 (B19) persists in rheumatoid arthritis (RA).

METHODS

Polymerase chain reaction (PCR) was used to detect parvovirus B19 genome in the synovial fluid cells or peripheral blood mononuclear cells from 61 patients with early RA; bone marrow from one patient was also studied. The synovium or synovial fluid cells from 28 patients with advanced RA, and synovial fluid cell samples from 18 patients with reactive arthritis (as controls) were studied. Two separate sets of primers and probe were used.

RESULTS

Parvovirus B19 specific gene sequences were detected in two patients with early arthritis fulfilling the criteria for RA.

CONCLUSION

Parvovirus B19 does not play a significant role in the aetiopathogenesis of RA. However, a few cases of a disease indistinguishable from RA may be triggered by parvovirus B19 infection.

Persistent B19 parvovirus infections in haemophilic HIV-1 infected patients

B19 infection can be acquired by transmission with blood factors in patients with congenital bleeding disorders, requiring clotting factor concentrates. In immunodeficient patients, the failure of immunity to clear B19 virus may produce persistent infections. The presence of B19 DNA in blood samples from seven haemophilic patients with concomitant HIV-1 infection was studied over a period of three-to-four years. Dot blot hybridization assays with DNA and RNA probes were used to detect medium high viremias, and polymerase chain reaction (PCR) to detect very low viremic titres. Three patients were negative for B19 DNA in all the blood samples, while four patients were persistently positive for B19 DNA. Viral persistence, which in one patient was detected throughout the study period (40 months), occurred at low titre in all four positive patients with some recurrent increases in viral titre. In the four patients persistently positive for B19 DNA, acute or chronic clinical symptoms and signs that could be associated with B19 were not noted when virus was present at low titre (B19 DNA detectable only by PCR). When patients had a higher viral titre (B19 DNA detectable by dot blot hybridization) acute manifestations (aplastic crisis, Fifth disease, fevers, pneumonitis) were found.

B19 parvovirus

B19 parvovirus is pathogenic in man and causes a variety of clinical illnesses, among them several haematological diseases. Acute infection of a host with underlying haemolysis produces transient aplastic crisis; of the midtrimester fetus, hydrops fetalis; and of an immunocompromised patient, pure red cell aplasia. The target of B19 parvovirus infection is the human erythroid progenitor cell. Infection is cytotoxic due to expression of the viral nonstructural protein. The virus can be propagated in cultures of human bone marrow, blood, and fetal liver. Humoral immunity normally terminates infection, and commercially available immunoglobulin can be used to treat persistent infection. Recombinant capsids, produced in a baculovirus system, are suitable as a vaccine reagent.

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

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

Parvovirus B19 as a cause of acquired chronic pure red cell aplasia

Parvovirus B19 infection causes chronic anaemia in immunodeficient individuals by selective suppression of erythropoiesis. The bone marrow morphology is characteristic of pure red cell aplasia (PRCA). To determine the frequency of B19-induced PRCA we retrospectively analysed a series of 57 PRCA patients. B19 DNA was present in serum of eight patients (14%) and could be extracted from bone marrow aspirate slides from five of these patients. Recent exposure to the virus was confirmed by the presence of anti-B19 IgM in sera from four and by the finding of giant pronormoblasts in marrow aspirates from five of the B19 DNA-positive patients. The sensitivities of anti-B19 IgM and of giant pronormoblasts were only 50% and 63%, respectively; specificities were 90% and 92%. Unexpectedly, PRCA in two B19 DNA-positive patients remitted after antilymphocyte globulin or cyclosporin A therapy, suggesting that the clinical course of B19-induced PRCA may be indistinguishable from other forms of PRCA. As therapy with immunoglobulin is uniformly effective for treatment of B19-associated anaemia, our data suggest that all patients with acquired PRCA should be evaluated for evidence of B19 infection. B19 DNA analysis is the most reliable method to demonstrate infection.

Chronic parvovirus B19 infection and systemic necrotising vasculitis: opportunistic infection or aetiological agent?

We describe three patients who had infection with human parvovirus B19 in association with new-onset systemic necrotising vasculitis syndromes, two with features of polyarteritis nodosa and one with features of Wegener's granulomatosis. Chronic B19 infection, lasting 5 months to more than 3 years, was shown by enzyme immunoassay for IgG and IgM antibodies to B19 and polymerase chain reaction for B19 DNA in serum and tissue samples. The patients had atypical serological responses to the B19 infection, although none had a recognisable immunodeficiency disorder. Treatment with corticosteroids and cyclophosphamide did not control vasculitis. Intravenous immunoglobulin (IVIG) therapy led to rapid improvement of the systemic vascultis manifestations, clearing of the chronic parvovirus infection, and long-term remission. These observations suggest an aetiological relation between parvovirus B19 infection and systemic necrotising vasculitis in these patients and indicate a potentially curative role for IVIG in such disorders.

Fetal damage caused by parvoviral infections

The single-stranded DNA parvoviruses occur in humans and many species of animals. In general, they are species-specific and capable of producing disease at any stage of life. Parvoviruses have a requirement to replicate in cells in a permissive S-phase of DNA mitosis. The infections may be cytolytic to select cell groups resulting in specific developmental defects or may produce more generalized effects such as anemia, pancytopenia, or hemorrhage. The fetus is at particular risk for damage because of the vast number of cells in active mitosis. The teratogenic effects may be severe, often resulting in fetal death. Infections in childhood and adulthood are more frequently mild to subclinical. Some of the teratogenic effects recognized in animal species have been identified in humans. With increased knowledge of parvovirus effects in animals, more pathogenic effects may be related to human parvoviral disease. The need for vaccination, currently used annually in many domestic animal species, continues to be evaluated for humans.

Human immunodeficiency virus type 1 (HIV-1) and human hematopoietic progenitor cells

Besides a progressive depletion of CD4+ T-lymphocytes, other peripheral blood cytopenias, (granulocytopenia, anemia and thrombocytopenia) are frequently observed in HIV-1 seropositive individuals, especially in patients with overt AIDS. Various experimental evidences suggest that HIV-1 could play a direct role in the pathogenesis of HIV-1 related peripheral blood cytopenias, affecting the survival/proliferation capacity of hematopoietic progenitors. CD34+ human hematopoietic progenitors, however, are substantially not susceptible to HIV-1 infection either in vitro and in vivo and their defects seem rather related to an alteration of bone marrow and peripheral blood microenvironments due to the presence of soluble HIV-1 specific products.

Evaluation of strand-specific RNA probes visualized by colorimetric and chemiluminescent reactions for the detection of B19 parvovirus DNA

A dot-blot hybridization assay was developed to detect B19 DNA using strand-specific RNA probes labelled with digoxigenin. The sensitivity of the assays was evaluated either using 'plus' and 'minus' sense RNA probes in two different hybridization assays, or in two successive reactions of the same assay. The hybridized probes were revealed immunoenzymatically using anti-digoxigenin Fab fragments conjugated with alkaline phosphatase. The enzyme was visualized by colorimetric reaction. Since 'minus' sense RNA probe gave the best results in the dot-blot procedures, we increased the sensitivity of the hybridization assay visualizing the 'minus' sense digoxigenin-labelled RNA probe by chemiluminescent reaction. In these experimental conditions up to 20 fg of target B19 DNA could be visualized. In the search for B19 DNA, 4656 serum samples were analyzed by chemiluminescent reaction of 'minus' sense digoxigenin-labelled RNA probe and for comparison with the digoxigenin-labelled DNA probe. Positive results were confirmed by Southern blotting. Out of 4656 serum samples analyzed, 4648 gave negative results, 1 resulted positive to all the hybridization assays, 6 only using RNA probe and 1 only by DNA probe.

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.

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.

Efficient parvovirus B19 DNA purification and molecular cloning

A simple and efficient method of purification and molecular cloning of Parvovirus B19 DNA directly from small quantities of viremic sera was developed. Purified virions were lysed in annealing conditions, then viral DNA purification in double strand (ds) DNA form was achieved using an affinity DNA binding matrix. Affinity purification yielded a consistently high recovery of viral DNA. Using affinity purified ds viral DNA, we efficiently and stably cloned the complete coding internal unique sequence of B19 DNA. In our cloning strategy AatII and BamHI restriction endonuclease sites were exploited. This permitted cleavage of the 5.0 kbp AatII fragment in two AatII-BamHI fragments which could be efficiently cloned in a directional way in pUC18 plasmid vector. The availability of the two cloned AatII-BamHI fragments thus allowed the construction of a full length clone in a single ligation reaction.

Persistence of B19 parvovirus in synovial membranes of patients with rheumatoid arthritis

Recent clinical observations support the hypothesis that persistent parvovirus B19 is a triggering factor of rheumatoid arthritis (RA) in certain genetically predisposed individuals. If this hypothesis is correct, a number of RA patients may exhibit parvovirus B19 DNA in their synovial membranes. We tested the synovial tissue and peripheral blood leukocytes of 20 patients with RA, 24 patients with other arthritides or osteoarthritis (non-RA), and 34 healthy blood donors for the presence of parvovirus B19 DNA using specific DNA amplification by polymerase chain reaction (PCR). Using this technique, parvovirus B19 DNA was demonstrated in the synovial biopsies of 75% of patients with RA but in those of only 16.7% of patients with non-RA. In autologous peripheral blood mononuclear cells the percentage of PCR-positive patients was about 15% in both RA and non-RA groups and did not differ from that in healthy controls. When the PCR data were correlated with the presence of anti-parvovirus B19 IgG antibodies in serum and synovia all patients with parvovirus B19 DNA in peripheral blood alone or in both peripheral blood and synovial membrane were seropositive. In contrast, about 40% of patients with parvovirus B19 DNA restricted to the synovial membrane were seronegative. These data indicate a highly disease-related persistence of parvovirus B19 in the rheumatoid synovium.