B19 IgG Antibodies Research Articles

Human parvovirus B19 infection in a renal transplant recipient: a case report

BackgroundParvovirus B19 presents tropism for human erythroid progenitor cells, causing chronic anemia in organ transplant recipients, due to their suppressed humoral and cellular responses. Diagnosis may be achieved through serological tests for detection of anti-B19 antibodies. However, renal transplant recipients are not routinely tested for parvovirus B19 infection, since there is scanty data or consensus on screening for B19 infection, as well as for treatment or preventive management of transplanted patients.Case presentationHerein we report a kidney transplant recipient, who was unresponsive to treatment of severe anemia, and presented hypocellular hematopoietic marrow, megaloblastosis and hypoplasia of erythroid lineage with larger cells with clear nuclei chromatin and eosinophilic nuclear inclusions. This patient was seropositive for Epstein-Barr and Cytomegalovirus infections and negative for anti-parvovirus B19 IgM and IgG antibodies, although symptoms were suggestive of parvoviruses infection. A qualitative polymerase chain reaction testing for B19 in serum sample revealed positive results for B19 virus DNA.ConclusionThis case report suggests that the diagnostic process for parvovirus B19 in renal transplant recipients should include a polymerase chain reaction assay to detect B19-DNA, since specific serological tests may be unreliable given their impaired humoral responses. These results also indicate the importance of considering parvovirus B19 infection in the differential diagnosis of persistent anemia in transplanted patients.

Seroprevalence of parvovirus B19 antibodies and evidence of viremia among Nigerian patients with sickle cell anemia.

Clinical, biochemical and molecular evidence for the sickle cell anemia (SCA) crisis in Nigerian patients arising from parvovirus b19 infection remains inadequate. This study determined the prevalence and correlates of anti-parvovirus b19 antibodies in a population of SCA patients and non-SCA healthy controls in Lagos, Nigeria. In this prospective cross-sectional study, we enrolled 73 confirmed SCA patients from 5 district hospitals in Lagos and 81 sex and age-matched non-SCA healthy controls. Serum sample from each study participant was screened for anti-parvovirus b19 by ELISA and PCR techniques. Standard biomedical assays were also done. Anti-parvovirus b19 IgM and IgG antibodies were detected in 22 (14.3%) and 97 (62.9%) of the 154 sera screened, 13 (17.8%) and 45 (61.6%) in SCA patients; 9 (11.1%) and 52 (64.2%) in non-SCA controls. The overall seronegativity rate was 19.5%. Parvovirus B19 DNA was found in 2 (11.1%) of the 18 IgM seropositive SCA serum samples screened. On the whole, parvovirus b19 infection was more commonly asymptomatic in non-SCA controls but caused significant elevation in liver enzymes in infected SCA patients (P < 0.05). The risk of acute parvovirus b19 infection increased 65 times during unsteady state among the SCA patients. Although no deaths of infected patients were recorded during the study, age below 12 years, hospitalization and overcrowded environment were risk factors for infection. We conclude that parvovirus b19 is common in SCA patients, incurring greater susceptibility to infections.

Detection of human parvovirus B19 in cancer patients using ELISA and real-time PCR

Purpose: Parvovirus B19 (B19) is associated with a wide range of diseases in humans, whose severity depends on the immunological and haematological status of the host. Objective: To determine the incidence of B19 DNA and specific IgM and IgG frequency among patients suffering from different haematological malignancies and to determine the viral load using real-time PCR. Materials and Methods: A total of 70 patients were included in the study, in addition to a control group consisting of 20 apparently healthy volunteers. B19 DNA quantitative analysis was performed using real-time PCR while screening for IgM and IgG anti-B19 antibodies was performed using ELISA. Results: B19 DNA was detected in 26 patients (36.14%) and 3 controls (15%) using real-time PCR. Anti-parvovirus B19 IgM antibodies were detected in 9 patients (12.6%) and 2 controls (10%). Anti-parvovirus B19 IgG antibodies were detected in 32 patients (45.71%) and 5 controls (25%). The difference between the patient and control groups was found to be statistically non-significant in all of the three tests (P < 0.05). The difference in B19 incidence among patients receiving multiple transfusions and non-transfused patients was also found to be statistically non-significant (P < 0.05). Conclusion: We found a high incidence of B19 infection among patients diagnosed with different types of haematological malignancies. We recommend that all cases of haematological disorders should be examined for specific antibodies and tested for the presence of B19 DNA in serum by PCR technique.

The Sero-Prevalence of Parvovirus Antibodies among Children with Sickle Cell Anaemia in Zaria

Parvovirus is an erythrovirus that infects red cell precursors in individuals with conditions characterised by a high red cell turnover like sickle cell anaemia and thalassaemia. Arthritis, vasculitis, carditis, bone marrow failure, and the slapped cheek appearance have been associated with Parvovirus B19 infection. Recurrent blood transfusion is a risk factor for the B19 serotype of Parvovirus infection, with the P antigen as the mediator for erythroid invasion presenting as transient erythroblastopaenia (TEB). Although TEB is self-limiting a few cases may progress to aplastic anaemia. Previous studies report seroprevalence rates of between 44 and 71%, but the dearth of data on the seroprevalence of B19 parvovirus strain in our region prompted this study. Venous blood samples from 239 children aged 1to 15 years of consenting parents and guardians were screened for Parvovirus B19 IgG antibodies using the ELISA technique and antibody titer assessed spectrophotometrically. All the participants have sickle cell anaemia, but were in the steady state. Of this serum samples from 204 (85.4%) participants were positive for IgG antibodies against Parvovirus B19 while 35 (14.6%) were negative for the IgG antibodies.). The age-group with the highest prevalence is 10-12year group with seroprevalence rate of 88.9%. The overall seroprevalence of Parvovirus B19 antibodies is 85.4 %. The seroprevalence of Parvovirus B19 antibodies is high in all socio-economic groups. Antibody prevalence is higher in thenon-transfused group suggesting that other factors than transfusion play a role in the spread of the B19 strain of Parvovirus B19.

Continued Transmission of Parvovirus B19 in Plasma-Derived Factor Concentrates After the Implementation of B19 Nucleic Acid Plasma Minipool Screening,

Abstract 3378 Background:Parvovirus B19 (B19) is a small, non-enveloped virus that causes a typically benign flu-like illness most commonly in childhood. However, B19 has been associated with arthritis and poses a hazard to the fetus of a pregnant woman. Because infection is common and viremia can occur before symptoms develop, about 1% of blood donations can be contaminated with B19 virus. The virus is resistant to current viral inactivation steps used in the manufacture of plasma-derived (P-D) anti-hemophilic factor concentrates and B19 transmission through these products has been documented. Since 2000, manufacturers have used a B19 nucleic acid test (NAT) to screen plasma pools and withhold from fractionation those with B19 DNA exceeding an established threshold. No study of populations using these products has been conducted to assess the impact of the screening on B19 transmission. Methods:Blood specimens obtained from participants of the CDC-sponsored Universal Data Collection (UDC) surveillance system of persons with bleeding disorders conducted by specialized US bleeding disorders clinics were used in a B19 seroprevalence study. Since B19 NAT screening began in 2000, only participants born after January 1, 2001 were eligible for study. Data collected on treatment products used by participants both prior to and after enrolment in UDC were used to categorize lifetime exposure as 1) no products, 2) recombinant (recomb) products only, 3) P-D products only, or 4) both recomb and P-D products. The proportions of participants with B19 IgG antibodies were compared across age and product exposure categories to determine whether users of products were at higher risk of past infection with B19 compared to those exposed to B19 only by the usual respiratory route. Results:A total of 1,643 specimens from 1,043 participants aged 2 – 7 years were tested. Demographic and clinical characteristics of study participants are shown in Table 1. Compared to subjects with no exposure to products, subjects in nearly every age group exposed to either P-D products alone or to both P-D and recomb products had a higher B19 prevalence (Table 2). In a logistic regression analysis that controlled for differences in the distribution of age, sex, bleeding disorder, treatment type, number of bleeds in previous 6 months, hemophilia inhibitor status, and year specimen obtained, participants exposed to P-D products alone were 1.7 times more likely to have B19 antibodies than those unexposed to blood or factor products (p = 0.002). In addition, there was a significant overall trend of increasing B19 prevalence over time.Table 1Characteristics of 1,043 children with bleeding disorders tested for exposure to Parvovirus B19.TotalCharacteristicN (%)Race/EthnicityWhite634 (60.8)Black125 (12.0)Hispanic194 (18.6)Other90 (8.6)SexMale870 (83.4)Female173 (16.6)Bleeding disorderHemophilia A537 (51.5)Hemophilia B141 (13.5)VWD322 (30.9)Other43 (4.1)Treatment typeEpisodic713 (68.4)Prophylaxis330 (31.6)Bleeds in past 6 mos.None462 (44.3)1 to 3363 (34.8)4+218 (20.9)Table 2Percent of specimens testing B19 positive by subject age and product exposure group.Age (years)NoneRecombinant onlyRecombinant and Plasma-derivedPlasma-derived only212.2 (90)19.0 (116)26.7* (15)32.3* (31)[7.0–20.6]323.5 (102)24.2 (124)15.4 (13)38.8* (49)[15.9–33.2]431.8 (126)35.6 (118)42.9* (21)48.7* (39)[23.9–40.7]538.8 (116)40.0 (125)50.0* (22)35.6 (45)[30.0–48.3]644.7 (94)50.4 (127)60.0* (15)56.2* (32)[34.5–55.3]750.0 (54)55.0 (129)50.0 (18)63.6 (22)[36.2–63.7]Number of samples tested in parentheses.Numbers in brackets are 95% confidence intervals (CI) for the proportion B19 seropositive.*p < 0.05 Discussion/Conclusion:P-D factor products are important therapies for people with VWD, hemophilia inhibitors and rarer factor deficiencies. Although we had no data on clinical illness, these serologic data provide evidence for continued transmission of B19 through these products after implementation of B19 NAT screening. Lowering the B19 threshold for plasma pool rejection should be considered. More importantly, effective viral inactivation processes are needed to protect users of these products not only from infection with B19 but from other as yet unidentified or emerging viruses that would not be detected by B19 NAT. Disclosures:Kessler:Novo Nordisk Inc.: Consultancy.

L’infection par l’érythrovirus B19 chez le drépanocytaire au Mali : une étude cas-témoins

Human parvovirus B19 (HP-19) is the only Parvoviridae known to be pathogenic in human. Studies of HP-19 infection and its associated life-threatening complications in sickle cell anemia patients have been reported in Europe and the US. These results justify the development of HP-B19 prevention and strategies to reduce the incidence of severe and life-threatening complications associated with the infection in patients with sickle cell anemia, particularly in sub-Saharan Africa where the sickle cell anemia burden is high. In light of these considerations, we conducted a case-control study including 163 patients with sickle cell anemia and 163 controls. HP-B19 diagnosis was based on the detection of IgG and IgM antibodies specific for HP-B19 using commercially available enzyme immunoassays. Anti-human parvovirus B19 IgG antibodies were found in 105 of 193 (64.8%) patients vs 79 of 193 controls (48.4%). IgM antibodies were found at a higher frequency in sickle cell anemia patients than in controls. This higher frequency was found to be age-dependent. However, the reticulocyte count showed no significant decrease in Malian patients with sickle cell anemia. Further studies are needed to better characterize the implication of HP-B19 infection in sickle cell anemia mortality and morbidity and to develop preventive strategies and efficient management of the resulting complications.

The prevalence of human parvovirus B19 DNA and antibodies in blood donors from four Chinese blood centers

Human parvovirus B19 is a common human pathogen that causes a variety of diseases with outcomes ranging from asymptomatic to severe, especially in immunocompromised patients. The B19 virus can be transmitted via blood and/or blood products and its resistance to common viral inactivation and/or removal methods raises the importance of B19-related blood safety. However, the existence, variation, and loading of B19 in Chinese blood donors have not been determined. Quantitative polymerase chain reaction (PCR) was developed to detect all three genotypes of the human erythrovirus DNA in plasma samples. In total, 3957 donations from four Chinese blood centers were screened for B19 by real-time minipool nucleic acid amplification technology (NAT). The positive samples were then confirmed by nested PCR and subjected to sequence analysis and alignment for phylogenetic studies. An enzyme-linked immunosorbent assay-based experiment was also performed to identify the prevalence of immunoglobulin (Ig)G and/or IgM antibodies specific to the B19 structural proteins in acquired samples. Of 3957 blood donors, 23 (0.58%) specimens were found positive for B19 DNA. The quantitative DNA levels ranged from 2.48 × 10(2) to 6.38 × 10(4) copies/mL. The phylogenic analyses showed that the prevalent genotypes in Chinese blood donors belong to B19 Genotype 1. A total of 448 samples from Chinese blood donors were investigated for the seroprevalence of B19 antibodies, among which 24.6 and 6.9% of specimens were seropositive for B19 IgG and IgM antibodies, respectively. A total of 2.5% of these samples were positive for both antibody isotypes. Whether B19 NAT screening of blood and blood products should be launched in China, larger studies are needed to facilitate an informed decision.

Parvovirus B19 antibodies and correlates of infection in pregnant women attending an antenatal clinic in central Nigeria

Human parvovirus B19 infection is associated with spontaneous abortion, hydrops foetalis, intrauterine foetal death, erythema infectiosum (5th disease), aplastic crisis and acute symmetric polyarthropathy. However, data concerning Nigerian patients with B19 infection have not been published yet. The purpose of this study was to establish the prevalence of B19 IgG and IgM antibodies, including correlates of infection, among pregnant women attending an antenatal clinic in Nigeria. Subsequent to clearance from an ethical committee, blood samples were collected between August-November 2008 from 273 pregnant women between the ages of 15-40 years who have given their informed consent and completed self-administered questionnaires. Recombinant IgG and IgM enzyme linked immunosorbent assay kits (Demeditec Diagnostics, Germany) were used for the assays. Out of the 273 participants, 111 (40.7%) had either IgG or IgM antibodies. Out of these, 75 (27.5%) had IgG antibodies whereas 36 (13.2%) had IgM antibodies, and those aged 36-40 years had the highest prevalence of IgG antibodies. Significant determinants of infection (p < 0.05) included the receipt of a blood transfusion, occupation and the presence of a large number of children in the household. Our findings have important implications for transfusion and foeto-maternal health policy in Nigeria. Routine screening for B19 IgM antibodies and accompanying clinical management of positive cases should be made mandatory for all Nigerian blood donors and women of childbearing age.

Parvovirus B19 and C-reactive protein in blood bank donors: implications for hygiene hypothesis research

Exposure to certain environmental factors during childhood may influence the developing immune system, causing predisposing or protective effects toward development of autoimmune disorders. This study examines the hypothesis that past infection with parvovirus B19, a common childhood infection, is associated with altered levels of subclinical inflammatory activity in presumably healthy adults. Qualitative anti-parvovirus B19 IgG antibody and high-sensitivity C-reactive protein were determined in serum samples from adult blood bank donors. C-reactive protein values of B19 IgG-positive and B19 IgG-negative groups were compared. Analysis was performed on 282 blood bank donor serum samples. Among donors aged 17-49 years (n = 152), B19 IgG-positive samples (57.9%) were associated with significantly lower C-reactive protein levels compared with B19 IgG-negative samples (median C-reactive protein: 1.30 mg/l vs. 2.65 mg/l; p = 0.012 unadjusted (Mann-Whitney U-test); p = 0.014 adjusted for gender and age (logistic regression)). Among donors aged >49 years, median C-reactive protein levels were identical by B19 IgG status. The association of B19 IgG antibody with lower C-reactive protein levels in the serum of younger adults supports the hypothesis that infection in childhood may contribute long-term beneficial adaptive immune responses.

Standardization of B19 IgG ELISA to study the seroepidemiology of parvovirus B19 in North Indian voluntary blood donors

Backgound and Objectives:Parvovirus B19 (B19) being a non-enveloped DNA virus is hence thermo-stable to the current methods of viral inactivation. Therefore transfusion of blood or its component from a viremic donor to non-immune recipients may result in transfusion-transmitted B19 infection with occasional sinister complications. The serologically naïve blood donor population in our country has not been studied. Hence a study was designed to find the sero-status of B19 virus in normal voluntary blood donor population (relatives of recipients) as an indirect measure of the susceptibility to B19 in north Indians together with seroepidemiology of B19.Methods:An in-house anti-B19 IgG ELISA was standardized using cloned, baculovirus expressed, and purified VP1/VP2 capsid proteins as antigen. Anti-B19 IgG antibodies in sera (diluted 1:400) of 1000 healthy voluntary blood donors (18-60 years; mean 30.5 years) were analyzed and their epidemiologic data were documented.Results:A total of 399 (39.9%) donors were seropositive for B19 virus. Seroprevalence was higher in males than females (44% vs 27%) and it increased with increasing age (P<0.01). Socioeconomically, B19 IgG antibody positivities were 61.8%, 61.1%, and 44.4% in low, medium, and high income groups respectively with unskilled laborers having higher seroprevalence in low (48.5%) and middle (58.7%) income group (P<0.05). Housing conditions revealed B19 seroprevalence as 42.6% in donors living in small houses compared to 20.4% in larger houses (P<0.01) but no difference with religion.Conclusions:Seroprevalence to B19 in normal voluntary blood donors was low leaving a large proportion of north Indians susceptible to B19 infection.

Gender differences in the relationship of anti-parvovirus B19 IgG with antinuclear antibody and C-reactive protein in clinical adult serum samples

Human parvovirus B19 (B19) infection is often suspected as an etiologic agent in a variety of rheumatologic diseases. It has been hypothesized that this virus potentially induces immune dysregulation by abnormal cytokine expression in susceptible hosts. The objective of this study is to examine the relationship between anti-parvovirus B19 IgG antibody (B19 IgG) and two common markers of immune dysregulation-antinuclear antibody (ANA) and C-reactive protein (CRP) in clinical sera. Qualitative B19 IgG antibody and levels of high-sensitivity CRP were determined in adult serum samples submitted to a university hospital clinical laboratory for ANA testing. Prevalence of B19 IgG was compared among groups by ANA status and CRP tertile. B19 IgG was detected in 72.3% of 318 samples. Among women above the first quartile of age (>38 years), presence of B19 IgG was associated with CRP tertile rank (P = 0.008) and CRP levels > or =1 mg/L (P = 0.001) independent of age and ANA status. B19 IgG was less frequent in ANA-positive than ANA-negative women < or =38 years of age (P = 0.009). Viral antibody was not associated with either biomarker in men. These data suggest parvovirus B19 infection may be associated with chronic inflammation in some women after the third decade of life.

Parvovirus B19 in Solid Organ Transplant Recipients

Parvovirus B19 is a common, ubiquitous human pathogen.It is a small, single-stranded linear, nonenveloped DNAvirus classified into three different genotypes (genotype1, Au and Wi strains; genotype 2, LaLi and A6 strains; andgenotype 3, V9 strains). Its worldwide genetic variability islow, and there is no clear correlation between genotypeand distinctive clinical manifestation. Parvovirus B19 repli-cates most efficiently and preferentially in human erythro-cyte precursors; thus, the virus is classified as a memberof the Erythrovirus genus of the Parvoviridae family. Mostpeople are infected between the ages of 5 and 15 years;by adulthood, up to 80% are seropositive (1). Infection ap-pears to confer lifelong immunity to immunocompetenthosts, but reinfection is possible in a minority of cases(2). It has been hypothesized that Parvovirus B19 can per-sist in the bone marrow and other tissues (3), support-ing possible reactivation rather than reinfection in certainseropositive patients. Parvovirus B19 infection can be ei-ther symptomatic or asymptomatic, depending on the age,hematologic and immunologic status of the host. Whilemostpatientsrecollectonlynonspecificflu-likesymptoms,distinctive clinical entities have been associated with Par-vovirus B19 infection in both immunocompetent hosts (4)and solid organ transplant (SOT) recipients (5). The mostcommonclinicalmanifestationsofParvovirusB19aresum-marizedinTable1.Although large, prospective surveillance studies are lack-ing, earlier studies reported an incidence of Parvovirus B19disease of

Seroprevalence of Erythrovirus B19 IgG Antibody among Paediatric Patients in Makkah and Jeddah, Kingdom of Saudi Arabia

Objective: To estimate the prevalence of IgG antibodies against B19 virus (B19V) in Makkah and Jeddah, Saudi Arabia. Methods: B19V-specific IgG antibodies were detected by a commercial indirect enzyme-linked immunosorbent assay in sera of 400 paediatric patients (185 males and 215 females) aged 1–17 years. Results: Of the 400 patients, 80 (20%) had sera positive for B19V-specific IgG. The difference in the prevalence of the antibodies between genders was not statistically significant (p = 0.9). The prevalence of anti-B19V antibodies increased significantly in the age group of 12–17 years as compared to younger patients (37.5 vs. 18% in those aged 1–11 years; p = 0.006). Conclusion: This study indicated a high prevalence of IgG antibodies against B19V in paediatric patients with an increase in age.

Children Transient Pancytopenia Preceding Hybrid Acute Leukemia

Transient pancytopenia preceding acute lymphoblastic leukemia (pre-ALL) is a rare event usually affecting children and adolescents. The aplastic episode may last for only some days or a few weeks and is generally followed by temporary normalization of peripheral blood counts prior to the subsequent development of overt ALL. ALL, usually of B-cell common type and infrequently of T-cell type, occurs in most of such cases within 6 months from the onset of the marrow aplasia. To the best of our knowledge, pre-ALL with a hybrid acute leukemia (HAL) immunophenotype has not been reported. The mechanism of pre-ALL remains obscure. Parvovirus B19, which exhibits a marked tropism to human BM and replicates only in erythroid progenitor cells causing anemia, thrombocytopenia, neutropenia, or a combination of all three in immunocompromised patients, may be one of possible explanations. We present the first case of B19-associated pre-ALL characterized by a HAL (T lymphocyte and myelocyte) immunophenotype. An 11-year-old boy presented with fever and rhinorrhagia. On physical examination, he had no lymphadenopathy or hepatosplenomegaly. A complete blood cell count revealed severe pancytopenia with haemoglobin 3.5g/L, white blood cells (WBC) 0.65×109/L and platelet count 3×109/L. Iliac bone marrow aspiration (BMA) showed hypoplasia with an absence of lymphoblasts. A diagnosis of acute aplastic anaemia was suspected, and he was treated with supportive treatment (antibiotics, granulocyte colony-stimulating factor, transfusion of blood and platelets). During a follow-up visit, 2 weeks after presentation, peripheral blood parameters and BMA became normal, and traditional Chinese drug was administered. At 8 weeks after presentation, he presented with leukocytosis. Physical examination Revealed extensive superficial lymphadenopathy, with no hepatosplenomegaly. Parvovirus B19 IgG and IgM antibodies were positive by enzymelinked immunosorbent assay, whereas B19- specific DNA was negative. Hepatitis virus A, B and C, HIV, EBV, and CMV serology were negative. The peripheral blood counts revealed WBC of 24×109/L with 5% blast cells and a BMA showed hyperplasia with 95% blast cells. Analysed by flow cytometry, the blast cells were divided into 2 groups: the major one (68% of all cells), being positive for the CD38, CD10, CD7, CD4, m/C CD3 antigens; another minor one (23%), being positive for the MPO, CD33, CD11, CD13, CD15, CD38, CD10, CD4, CD7, m/C CD3 antigens. Positive expression of membrane antigens supported a diagnosis of HAL (T lymphocyte and myelocyte). Conventional cytogenetic analysis revealed normal karyotype and T-cell receptor γ gene rearrangement was noted. The patient achieved complete remission after one cycle of VDCAD regimen (vincristin, daunorubicin, cyclophosphamide, cytarabine and dexamethasone). However, 1 months after complete remission, the patient relapsed. He achieved the second complete remission after reinduction regimen and gived up further chemotherapy. In this report, we document that pre-ALL may precede HAL (T lymphocyte and myelocyte) for the first time. B19 is possibly one of several factors capable of triggering the onset of pre-ALL.

Seroprevalence of human parvovirus B19 in a suburban population in São Paulo, Brazil

OBJECTIVE: To analyze the prevalence of IgG antibodies to human parvovirus B19. METHODS: Cross-sectional study in a suburban community in São Paulo, Southeastern Brazil, between November 1990 and January 1991. Randomly selected (N=435) representative samples of sera were collected from healthy children older than 15 days old and adults up to 40 years old. IgG antibodies were detected using ELISA. RESULTS: High prevalence of IgG antibodies to B19 parvovirus was found in 87% of newborns. The prevalence of maternally derived IgG antibodies exponentially plunged up to the 19th month of age. Low prevalence of antibodies was found in the first 4 years of life, increasing up to 72% in those aged 31-40 years. It was estimated that the average age of first infection in this population is 21 ± 7 years old and the optimal age for vaccination with a hypothetical vaccine would be 1 year of age. CONCLUSIONS: Parvovirus B19 IgG antibody prevalence was high in newborns and those aged 31-40 years. The analysis by age groups showed a pattern similar to that found in previous studies, i.e., low prevalence of infection in children that increases with age.

Seroprevalence of human parvovirus B19 in a suburban population in São Paulo, Brazil

To analyze the prevalence of IgG antibodies to human parvovirus B19. Cross-sectional study in a suburban community in São Paulo, Southeastern Brazil, between November 1990 and January 1991. Randomly selected (N=435) representative samples of sera were collected from healthy children older than 15 days old and adults up to 40 years old. IgG antibodies were detected using ELISA. High prevalence of IgG antibodies to B19 parvovirus was found in 87% of newborns. The prevalence of maternally derived IgG antibodies exponentially plunged up to the 19th month of age. Low prevalence of antibodies was found in the first 4 years of life, increasing up to 72% in those aged 31-40 years. It was estimated that the average age of first infection in this population is 21 +/- 7 years old and the optimal age for vaccination with a hypothetical vaccine would be 1 year of age. Parvovirus B19 IgG antibody prevalence was high in newborns and those aged 31-40 years. The analysis by age groups showed a pattern similar to that found in previous studies, i.e., low prevalence of infection in children that increases with age.

Parvovirus B19 infection in Tunisian patients with sickle-cell anemia and acute erythroblastopenia

BackgroundHuman parvovirus B19 is the etiologic agent of erythema infectiosum in children. It is also associated with other clinical manifestations in different target groups. Patients with chronic hemolytic anemia are at high risk of developing acute erythroblastopenia following infection by the virus. They usually become highly viremic and pose an increased risk of virus transmission. Close monitoring of such high risk groups is required for epidemiologic surveillance and disease prevention activities. Here we report a molecular epidemiological study on B19 virus infection in Tunisian patients with chronic hemolytic anemia.MethodsThis study was conducted on 92 young chronic hemolytic anemia patients who attended the same ward at the National Bone Marrow Transplantation Center of Tunis and 46 controls from a different hospital. Screening for IgM and IgG anti-B19 antibodies was performed using commercially available enzyme immunoassays and B19 DNA was detected by nested PCR in the overlapping VP1/VP2 region. DNA was sequenced using dideoxy-terminator cycle sequencing technology.ResultsAnti-parvovirus B19 IgG antibodies were detected in 26 of 46 sickle-cell anemia patients, 18 of 46 β-thalassemia and 7 of 46 controls. Anti-parvovirus B19 IgM antibodies were detected only in 4 of the sickle-cell anemia patients: two siblings and two unrelated who presented with acute erythroblastopenia at the time of blood collection for this study and had no history of past transfusion. B19 DNA was detected only in sera of these four patients and the corresponding 288 bp nested DNA amplicons were sequenced. The sequences obtained were all identical and phylogenetic analysis showed that they belonged to a new B19 virus strain of Genotype1.ConclusionA new parvovirus B19 strain of genotype1 was detected in four Tunisian patients with sickle-cell anemia. Virus transmission appeared to be nosocomial and resulted in acute erythroblastopenia in the four patients. The possibility of independent transmission of this B19 variant to the patients is unlikely in light of the present epidemiological data. However this possibility cannot be ruled out because of the low genetic variability of the virus.

Comparative evaluation of two commercial enzyme immunoassays for serodiagnosis of human parvovirus B19 infection

The present study describes the performance of two commercial enzyme immunoassays (EIAs) employing recombinant capsid proteins derived from baculovirus or from yeast for diagnosis of human parvovirus B19 (B19) infection. At first, 450 sera from routine daily practice submitted consecutively for B19 antibody testing during a 2-week period in March 2006 were tested. Eighty percent of the routine sera were from pregnant women. There was a high degree of accordance between the two assay systems in detection of B19 IgG antibodies (98.9%) and B19 IgM antibodies (98.7%). Specific antibody concentrations of serum specimens with discordant test results ( n = 11) were within or close to the equivocal range of the respective assay. Subsequently, specificity and sensitivity of the IgM EIAs were assessed in detail by testing 160 sera collected from patients with a defined disease state. Specificity ranged between 94.2 and 98.5% in patients ( n = 70) with other acute infections or autoimmune diseases. In sera from pregnant women ( n = 30) and children ( n = 30) with acute B19 infection, both assays were 100% sensitive. Whereas sensitivity varied from 63.0 to 70.0% in pregnant women ( n = 30) investigated 8–12 weeks after onset of disease. According to our evaluation the diagnostic performance of the two assay systems appears to be substantially equivalent. Fetal hydrops is sometimes a late complication of gestational B19 infection and maternal B19 IgM antibodies may already have declined to undetectable levels at the time of clinical diagnosis. A negative B19 IgM test during pregnancy should therefore be interpreted with caution.

Improved detection of acute parvovirus B19 infection by immunoglobulin M EIA in combination with a novel antigen EIA

Although parvovirus B19 is a significant blood product contaminant, few methods other than polymerase chain reaction (PCR) have been developed to detect the presence of the virus. A B19 antigen enzyme immunoassay (EIA) has been developed and the sensitivity of detection is ascertained using dilutions of the B19 capsid protein VP2 and 10-fold dilutions of B19 viraemic serum. Once the assay cut-off was established, a panel of viraemic donations (n = 70) was screened by the antigen EIA. The B19 immunoglobulin M (IgM) and IgG status of these specimens was also determined. During screening of blood donor units by quantitative PCR, 70 individuals were identified with levels of B19 DNA greater than 10(6) IU/ml at the time of blood donation. The sensitivity of the B19 antigen EIA was estimated to be equivalent to between 10(8) and 10(9) IU/ml B19 DNA or 1-10 pg/ml of recombinant capsid protein. B19 detection was significantly enhanced when viraemic specimens were pretreated with a low pH proprietary reagent. Unlike other virus-detection assays, detection of the B19 antigen was not affected by the presence of B19 IgM or IgG antibodies. In addition, the assay was capable of detecting all three genotypes of human erythrovirus. Combined specimen analysis by the B19 antigen assay and a B19 IgM assay facilitated the detection of 91% of acute B19 infections in the test population. In combination with B19 IgM detection, application of the B19 antigen EIA is a flexible and efficient method of detecting recent B19 infection and can be used as an alternative to PCR.

Prevalência de anticorpos IgG antiparvovírus B19 em gestantes durante o atendimento pré-natal e casos de hidropisia fetal não imune atribuídos ao parvovírus B19, na Cidade do Rio de Janeiro

With the aim of measuring the prevalence of anti-parvovirus B19 IgG antibodies during pregnancy up to 24 weeks of gestation and detecting cases of nonimmune hydrops fetalis, 249 sera from pregnant women attending a reference hospital in Rio de Janeiro city, from June 2003 to November 2004 were collected. They were followed-up until the end of pregnancy, with 17 cases of fetal hydrops detected. Four cases were caused by parvovirus B19 and two of them occurred in pregnant women living in the western zone of the city, during February 2005. Anti-parvovirus B19 IgG antibodies were found in 172 (71.6%) pregnant women (CI 95% 65.5%-77.7%); this antibody prevalence is similar to results found for others Brazilian cities. The only variable associated with previous acquisition of IgG antibodies to parvovirus B19 was number of pregnancies greater than one (p= 0.02, CI 95% 0.36-0.94).