Longitudinal assessment of the CXCL10 blood and urine concentration in kidney transplant recipients with BK polyomavirus replication-a retrospective study.

In kidney transplant recipients (KTRs), BK polyomavirus (BKPyV) replication may progress to polyomavirus-associated nephropathy (PVAN). In this retrospective study, we assessed the chemokine CXCL10 in urine and blood samples consecutively acquired from 85 KTRs who displayed different stages of BKPyV replication and eventually developed PVAN. In parallel to progression toward PVAN, CXCL10 gradually increased in blood and urine, from baseline (prior to virus replication) to BKPyV DNAuria (median increase in blood: 42.15 pg/ml, P = 0.0156), from mere DNAuria to low- and high-level BKPyV DNAemia (median increase: 52.60 and 87.26 pg/ml, P = 0.0010 and P = 0.0002, respectively) and peaked with histologically confirmed PVAN (median increase: 145.00 pg/ml, P < 0.0001). CXCL10 blood and urine levels significantly differed among KTRs with respect to simultaneous presence of human cytomegalovirus (P < 0.001) as well as in relation to the clinical severity of respective BKPyV DNAemia episodes (P = 0.0195). CXCL-10 concentrations were particularly lower in KTRs in whom BKPyV DNAemia remained without clinical evidence for PVAN, as compared to individuals who displayed high decoy cell levels, decreased renal function and/or biopsy-proven PVAN (median blood concentration: 266.97 vs. 426.42 pg/ml, P = 0.0282). In conclusion, in KTRs CXCL10 rises in parallel to BKPyV replication and correlates with the gradual development of PVAN.

The Chemokine CXCL-10 Is a Marker of Infection Stage in Individuals With DNAemia Due to Parvovirus B19.

Background: Accurate diagnosis of parvovirus B19 (B19V) infection requires the differentiation between acute and past infection, which is especially important when DNAemia due to B19V (hereafter, "B19V DNAemia") is detected in pregnancy. Here, we explored whether the level of the chemokine CXCL-10, in combination with findings of molecular and serological assays, can discriminate between acute and past B19V infection. Methods: B19V DNA-positive serum samples from 222 immunocompetent individuals were analyzed for (1) viral DNA loads, (2) anti-B19V immunoglobulin M (IgM) and immunoglobulin G (IgG), (3) anti-VP1 IgG avidity, (4) anti-VP-2 epitope type specificity (ETS), and (5) CXCL-10 serum levels. Results: Anti-B19V IgM and IgG, avidity, and ETS assays were used to categorize individuals with B19V DNAemia as having acute or past B19V infection. Acute B19V infection caused a significant increase in the serum concentration of CXCL-10, compared with the concentration at baseline, before infection. Higher CXCL-10 serum levels were furthermore detected in acute B19V infection as compared to past infection. As a marker, CXCL-10 serum levels could discriminate between acute and past B19V infection, with an excellent discriminatory capacity when CXCL-10 and B19V DNA levels were used as combined parameters. Conclusion: Acute B19V infection is associated with increased CXCL-10 production, and measurement of CXCL-10 serum levels thus allows for the staging of B19V infection in individuals with B19V DNAemia.

Microsphere-based antibody assays for human parvovirus B19V, CMV and T. gondii.

BACKGROUND: Human parvovirus B19 (B19V), cytomegalovirus (CMV) and Toxoplasma gondii (T. gondii) may cause intrauterine infections with potentially severe consequences to the fetus. Current serodiagnosis of these infections is based on detection of antibodies most often by EIA and individually for each pathogen. We developed singleplex and multiplex microsphere-based Suspension Immuno Assays (SIAs) for the simultaneous detection of IgG antibodies against B19V, CMV and T. gondii. METHODS: We tested the performances of SIAs as compared to in-house and commercial reference assays using serum samples from well-characterized cohorts. RESULTS: The IgG SIAs for CMV and T. gondii showed good concordance with the corresponding Vidas serodiagnostics. The B19V IgG SIA detected IgG in all samples collected >10 days after onset of symptoms and showed high concordance with EIAs (in-house and Biotrin). The serodiagnostics for these three pathogens performed well in multiplex format. CONCLUSIONS: We developed singleplex and multiplex IgG SIAs for the detection of anti-B19V, -CMV and -T. gondii antibodies. The SIAs were highly sensitive and specific, and had a wide dynamic range. These components thus should be suitable for construction of a multiplex test for antibody screening during pregnancy.

Original antigenic sin with human bocaviruses 1-4.

Human bocavirus (HBoV) 1 is a widespread parvovirus causing acute respiratory disease in young children. In contrast, HBoV2 occurs in the gastrointestinal tract and is potentially associated with gastroenteritis, whilst HBoV3 and -4 infections are less frequent and have not yet been linked with human disease. Due to HBoV1 DNA persistence in the nasopharynx, serology has been advocated as a better alternative for diagnosing acute infections. In constitutionally healthy children, we previously noted that pre-existing HBoV2 immunity in a subsequent HBoV1 infection typically resulted in low or non-existent HBoV1-specific antibody responses. A phenomenon describing such immunological events among related viruses has been known since the 1950s as 'original antigenic sin' (OAS). The aim of this study was to characterize this putative OAS phenomenon in a more controlled setting. Follow-up sera of 10 rabbit pairs, inoculated twice with HBoV1-4 virus-like particles (VLPs) or control antigens, in various combinations, were analysed with HBoV1-4 IgG enzyme immunoassays with and without depletion of heterotypic HBoV antibodies. There were no significant IgG boosts after the second inoculation in either the heterologously or the homologously HBoV-inoculated rabbits, but a clear increase in cross-reactivity was seen with time. We could, however, distinguish a distinct OAS pattern from plain cross-reactivity: half of the heterologously inoculated rabbits showed IgG patterns representative of the OAS hypothesis, in line with our prior results with naturally infected children. HBoVs are the first parvoviruses to show the possible existence of OAS. Our findings provide new information on HBoV1-4 immunity and emphasize the complexity of human bocavirus diagnosis.

Diagnostic methods for and clinical pictures of polyomavirus primary infections in children, Finland.

We used comprehensive serodiagnostic methods (IgM, IgG, and IgG avidity) and PCR to study Merkel cell polyomavirus and trichodysplasia spinulosa-associated polyomavirus infections in children observed from infancy to adolescence. Comparing seroconversion intervals with previous and subsequent intervals, we found that primary infections with these 2 viruses were asymptomatic in childhood.

Identification of past and recent parvovirus B19 infection in immunocompetent individuals by quantitative PCR and enzyme immunoassays: a dual-laboratory study.

Parvovirus B19 (B19V) is a member of the family Parvoviridae, genus Erythrovirus. B19V-specific IgG and IgM react differently against conformational and linear epitopes of VP1 and VP2 antigens, leading to the development of IgG avidity and epitope type specificity (ETS) enzyme immunoassays (EIAs) for distinguishing past from recent infection. Additionally, B19V viral load determination (by quantitative PCR [qPCR]) is increasingly used in the staging of B19V infection. In this study, the utility of these methods is compared. A panel of 78 sera was jointly tested by the Virus Reference Department (VRD), London, United Kingdom, and the Haartman Institute (HI), Helsinki, Finland, using a number of EIAs, e.g., B19V-specific IgG and IgM, IgG avidity, and ETS EIAs. At VRD, the sera were also tested by a B19V viral load PCR (qPCR). By consensus analysis, 43 (55.1%) sera represented past infection, 28 (35.9%) sera represented recent infection, and 7 (9.0%) sera were indeterminate. Both VRD B19V qPCR and HI B19V VP2 IgM EIA gave the highest agreement with consensus interpretation for past or recent infection, with an overall agreement of 99% (95% confidence interval [CI], 92 to 100) and positive predictive value (PPV) of 100% (95% CI, 87 to 100). Nine sera designated as representing past infection by consensus analysis were B19V IgM positive by a commercial VRD B19V IgM EIA and B19V IgM negative by a new HI in-house B19V VP2 IgM EIA. A new VRD B19V IgG avidity EIA showed good (>95%) agreement (excluding equivocal results) with consensus interpretations for past or recent infection. Correct discrimination of past from recent B19V infection was achieved through application of qPCR or by appropriate selection of EIAs.

Increased risk of human parvovirus B19 infection in day-care employees: a cohort study among pregnant workers during an epidemic in Finland.

BACKGROUND: Human parvovirus B19 (B19V) infection during early pregnancy increases the risk of miscarriage. Studies have inconsistently shown an elevated risk of infection among women with occupational contacts with children. Methodological differences, particularly in defining occupational exposure and in the type of reference group, may explain the conflicting findings. METHODS: This cohort study compared B19V infections in pregnant day-care employees and healthcare professionals during a B19V epidemic in Finland. Women were identified from the files of nationwide trade unions and the National Supervisory Authority for Welfare and Health. Early-pregnancy maternal B19V IgG was analysed in 3710 women, and infections were defined as seroconversions after analysing in parallel the available umbilical cord blood samples of the 847 seronegative mothers. Independently of the serological status, the actual employment during pregnancy was assessed using registered information on employment history. RESULTS: B19V infections were more common among day-care employees (22/331, 6.6%), than among those working in healthcare (12/326, 3.7%). The adjusted HRs of B19V infection, using proportional hazard regression, was 2.63 (95% CI 1.27 to 5.46) among all women and 5.59 (95% CI 1.40 to 22.4) among nulliparous women. CONCLUSIONS: Day-care employees are at an increased risk of B19V infection, which warrants preventive measures.

Human bocaviruses are commonly found in stools of hospitalized children without causal association to acute gastroenteritis.

UNLABELLED: Human bocaviruses (HBoVs) may be grouped into respiratory (HBoV1) and enteric (HBoV2-4) types. We examined this association of HBoV types and clinical symptoms in 955 children who had acute gastroenteritis (AGE, n = 172), acute respiratory tract infection (ARTI, n = 545) or symptoms of both (n = 238). Both nasal swab and stool specimens were studied for such patients. HBoV1 DNA was detected in 6.2 % of patients with ARTI and 9.2 % of patients with symptoms of both ARTI and AGE, but in only 1.7 % of patients with AGE alone. In about one half of the cases, HBoV1 was detected concomitantly in nasal swab and stool samples. HBoV2 was found in stool samples of patients with AGE (5.8 %), ARTI (5.1 %) and symptoms of both (5.5 %) but only rarely in nasal swabs. HBoV3 was found in the stools, but not in nasal swabs, in 0.6, 1.1 and 0.8 % of patients with, respectively, AGE, ARTI and both. HBoV4 was not found. All but one HBoV-positive stool sample of AGE patients contained a known gastroenteritis virus (rotavirus, norovirus, sapovirus, astrovirus or enteric adenovirus) that was probably responsible for the symptoms of the respective case. Sera of 30 HBoV-positive patients were available, and IgM antibodies for HBoVs were found in ten cases and HBoV DNA in eight of these. CONCLUSIONS: HBoV2 and HBoV3 were more commonly found in stool than in nasal swab samples, but the findings could not be causally linked with AGE. HBoV1 was commonly found in stool samples during ARTI, with or without gastrointestinal symptoms.

Possible involvement of human bocavirus 1 in the death of a middle-aged immunosuppressed patient.

An immunosuppressed 61-year-old man went to the hospital with fever, nonproductive cough, and increasing shortness of breath. The subject died 8 days later of respiratory complications. PCR of respiratory samples as well as a blood sample revealed exceptionally high DNA levels of the emerging pathogen, human bocavirus 1 (HBoV1), a recently found pathogen associated with respiratory symptoms in young children. We describe the clinical progression of the case and discuss the potential role of HBoV1 in the outcome.

Association of human bocavirus 1 infection with respiratory disease in childhood follow-up study, Finland.

Human bocavirus 1 (HBoV1) DNA is frequently detected in the upper airways of young children with respiratory symptoms. Because of its persistence and frequent co-detection with other viruses, however, its etiologic role has remained controversial. During 2009-2011, using HBoV1 IgM, IgG, and IgG-avidity enzyme immunoassays and quantitative PCR, we examined 1,952 serum samples collected consecutively at 3- to 6-month intervals from 109 constitutionally healthy children from infancy to early adolescence. Primary HBoV1 infection, as indicated by seroconversion, appeared in 102 (94%) of 109 children at a mean age of 2.3 years; the remaining 7 children were IgG antibody positive from birth. Subsequent secondary infections or IgG antibody increases were evident in 38 children and IgG reversions in 10. Comparison of the seroconversion interval with the next sampling interval for clinical events indicated that HBoV1 primary infection, but not secondary immune response, was significantly associated with acute otitis media and respiratory illness.

Occurrence of human bocaviruses and parvovirus 4 in solid tissues.

Human bocaviruses 1-4 (HBoV1-4) and parvovirus 4 (PARV4) are recently discovered human parvoviruses. HBoV1 is associated with respiratory infections of young children, while HBoV2-4 are enteric viruses. The clinical manifestations of PARV4 remain unknown. The objective of this study was to determine whether the DNAs of HBoV1-4 and PARV4 persist in human tissues long after primary infection. Biopsies of tonsillar tissue, skin, and synovia were examined for HBoV1-4 DNA and PARV4 DNA by PCR. Serum samples from the tissue donors were assayed for HBoV1 and PARV4 IgG and IgM antibodies. To obtain species-specific seroprevalences for HBoV1 and for HBoV2/3 combined, the sera were analyzed after virus-like particle (VLP) competition. While HBoV1 DNA was detected exclusively in the tonsillar tissues of 16/438 individuals (3.7%), all of them ≤8 years of age. HBoV2-4 and PARV4 DNAs were absent from all tissue types. HBoV1 IgG seroprevalence was 94.9%. No subject had HBoV1 or PARV4 IgM, nor did they have PARV4 IgG. The results indicate that HBoV1 DNA occurred in a small proportion of tonsils of young children after recent primary HBoV1 infection, but did not persist long in the other tissue types studied, unlike parvovirus B19 DNA. The results obtained by the PARV4 assays are in line with previous results on PARV4 epidemiology.

Seroepidemiology of human bocaviruses 1-4.

BACKGROUND: Recently, 3 new members of the genus Bocavirus, human bocavirus 2 (HBoV2), human bocavirus 3 (HBoV3), and human bocavirus 4 (HBoV4), were discovered. HBoV2-4 occur mainly in the gastrointestinal tract but rarely in the respiratory tract, contrary to human bocavirus 1 (HBoV1). METHODS: To investigate HBoV1-4 seroepidemiology among 195 adults and 252 wheezing children, we conducted immunoglobulin G (IgG) and immunoglobulin M (IgM) enzyme immunoassays with recombinant viruslike particles (VLPs). The children's sera were also tested for HBoV1-4 DNA by quantitative polymerase chain reaction (qPCR). RESULTS: Both rabbit and human antibodies to HBoV1-4 VP2 VLPs were found to be cross-reactive. After depletion of HBoV1-reactive antibodies, the HBoV2-4 approximate seroprevalences in adults were 34%, 15%, and 2% and in children aged 1-2 years 25%, 10%, and 5%, respectively. After depletion of HBoV2-4-reactive antibodies, the HBoV1 seroprevalence among adults decreased from 96% to 59%. No cross-reactivity of human anti-HBoV IgG was observed with bovine parvovirus1, parvovirus B19 or PARV4. No child was HBoV2-4 viremic. CONCLUSIONS: HBoV2-4 infect humans less commonly and elicit weaker B-cell responses than HBoV1. In our study HBoV2-4 did not seem to have a major etiological role in wheezing. Cross-reactivity with HBoV2-4 IgG partially accounts for the high HBoV1 seroprevalences previously reported. Correction for cross-reactivity is a prerequisite for VLP-based HBoV seroepidemiology.

Serodiagnosis of primary infections with human parvovirus 4, Finland.

To determine the prevalence of parvovirus 4 infection and its clinical and sociodemographic correlations in Finland, we used virus-like particle-based serodiagnostic procedures (immunoglobulin [Ig] G, IgM, and IgG avidity) and PCR. We found 2 persons with parvovirus 4 primary infection who had mild or asymptomatic clinical features among hepatitis C virus-infected injection drug users.

Comparison of approaches for IgG avidity calculation and a new highly sensitive and specific method with broad dynamic range.

BACKGROUND: Antimicrobial IgG avidity is measured in the diagnosis of infectious disease, for dating of primary infection or immunization. It is generally determined by either of two approaches, termed here the avidity index (AI) or end-point ratio (EPR), which differ in complexity and workload. While several variants of these approaches have been introduced, little comparative information exists on their clinical utility. METHODS: This study was performed to systematically compare the performances of these approaches and to design a new sensitive and specific calculation method, for easy implementation in the laboratory. The avidities obtained by AI, EPR, and the newly developed approach were compared, across parvovirus B19, cytomegalovirus, Toxoplasma gondii, rubella virus, and Epstein-Barr virus panels comprising 460 sera from individuals with a recent primary infection or long-term immunity. RESULTS: With optimal IgG concentrations, all approaches performed equally, appropriately discriminating primary infections from past immunity (area under the receiver operating characteristic curve (AUC) 0.93-0.94). However, at lower IgG concentrations, the avidity status (low, borderline, high) changed in 17% of samples using AI (AUC 0.88), as opposed to 4% using EPR (AUC 0.91) and 6% using the new method (AUC 0.93). CONCLUSIONS: The new method measures IgG avidity accurately, in a broad range of IgG levels, while the popular AI approach calls for a sufficiently high antibody concentration.

Microsphere-Based IgM and IgG Avidity Assays for Human Parvovirus B19, Human Cytomegalovirus, and Toxoplasma gondii.

Human parvovirus B19 (here B19), human cytomegalovirus (HCMV), and Toxoplasma gondii infections during pregnancy can lead to severe complications. While traditional diagnosis of infections is mostly confined to one pathogen at a time, a multiplex array is a feasible alternative to improve diagnostic management and cost-efficiency. In the present study, for these three pathogens, we developed microsphere-based suspension immunoassays (SIAs) in multiplex and monoplex formats for the detection of antimicrobial IgM antibodies as well as corresponding chaotrope-based IgG avidity SIAs. We determined the diagnostic performances of the SIAs versus in-house and commercial reference assays using a panel of 318 serum samples from well-characterized clinical cohorts. All the newly developed assays exhibited excellent performance compared to the corresponding high-quality reference methods. The positive and negative percent agreements of the IgM SIAs in comparison with reference methods were 95 to 100% and 98 to 100%, and those of the IgG avidity SIAs were 92 to 100% and 95 to 100%, respectively. Kappa efficiency values between the SIAs and the corresponding reference assays were 0.91 to 1. Furthermore, with another panel comprising 391 clinical samples from individuals with primary infection by B19, HCMV, or T. gondii, the IgM SIAs were highly sensitive for the detection of acute infections, and the IgG avidity SIAs were highly specific for the separation of primary infections from past immunity. Altogether, the strategy of IgM multiplex screening followed by IgG avidity reflex testing can provide high-throughput and accurate means for the detection and stage determination of B19, HCMV, and T. gondii infections.IMPORTANCE Human parvovirus B19, human cytomegalovirus, and Toxoplasma gondii are ubiquitous pathogens. Their infections are often asymptomatic or mild in the general population yet may be transmitted from mother to fetus during pregnancy. Maternal infections by these pathogens can cause severe complications to the fetus or congenital abnormalities. As a rule, the risk of maternal transmission is critically related to the infection time; hence, it is important to determine when a pregnant woman has acquired the infection. In this study, we developed new diagnostic approaches for the timing of infections by three pathogens. All the new assays appeared to be highly sensitive and specific, providing powerful tools for medical diagnosis.

Clinical assessment and improved diagnosis of bocavirus-induced wheezing in children, Finland.

Human bocavirus (HBoV) is a widespread respiratory virus. To improve diagnostic methods, we conducted immunoglobulin (Ig) G and IgM enzyme immunoassays with recombinant virus-like particles of HBoV as antigen. Acute-phase and follow-up serum samples from 258 wheezing children and single serum samples from 115 healthy adults in Finland were examined. Our assays had a sensitivity of 97% and a specificity of 99.5%. Of adults, 96% had immunity; none had an acute infection. Of 48 children with serologically diagnosed acute HBoV infections, 45 were viremic and 35 had virus in nasopharyngeal aspirates (NPAs). Of 39 HBoV NPA PCR-positive children co-infected with another virus, 64% had a serologically verified HBoV infection. HBoV caused illness of longer duration than rhinovirus and of equal severity to that of respiratory syncytial virus. Among children with bronchiolitis, >25% had acute HBoV infections. Accurate HBoV diagnosis requires serologic analysis or PCR of serum; PCR of NPAs alone is insufficient.

Acute human bocavirus 1 infection in child with life-threatening bilateral bronchiolitis and right-sided pneumonia: a case report.

BACKGROUND: Human bocavirus 1 is a commonly detected human parvovirus. Many studies have shown human bocavirus 1 as a pathogen in association with acute respiratory tract infections in children. However, because human bocavirus 1 persists in the upper airways for extensive time periods after acute infection, the definition and diagnostics of acute human bocavirus 1 infection is challenging. Until now, detection of human bocavirus 1 exclusively, high viral load in respiratory samples, and viremia have been associated with a clinical picture of acute respiratory illness. There are no studies showing detection of human bocavirus 1 messenger ribonucleic acid in the peripheral blood mononuclear cells as a diagnostic marker for acute lower respiratory tract infection. CASE PRESENTATION: We report the case of a 17-month-old Latvian boy who presented in intensive care unit with acute bilateral bronchiolitis, with a history of rhinorrhea and cough for 6 days and fever for the last 2 days prior to admission, followed by severe respiratory distress and tracheal intubation. Human bocavirus 1 was the only respiratory virus detected by a qualitative multiplex polymerase chain reaction panel. For the diagnosis of acute human bocavirus 1 infection, both molecular and serological approaches were used. Human bocavirus 1 deoxyribonucleic acid (DNA) was detected simultaneously in nasopharyngeal aspirate, stool, and blood, as well as in the corresponding cell-free blood plasma by qualitative and quantitative polymerase chain reaction, revealing high DNA-copy numbers in nasopharyngeal aspirate and stool. Despite a low-load viremia, human bocavirus 1 messenger ribonucleic acid was found in the peripheral blood mononuclear cells. For detection of human bocavirus 1-specific antibodies, non-competitive immunoglobulin M and competitive immunoglobulin G enzyme immunoassays were used. The plasma was positive for both human bocavirus 1-specific immunoglobulin M and immunoglobulin G antibodies. CONCLUSIONS: The presence of human bocavirus 1 genomic DNA in blood plasma and human bocavirus 1 messenger ribonucleic acid in peripheral blood mononuclear cells together with human bocavirus 1-specific immunoglobulin M are markers of acute human bocavirus 1 infection that may cause life-threatening acute bronchiolitis.

Serodiagnosis of human bocavirus infection.

BACKGROUND: A new human-pathogenic parvovirus, human bocavirus (HBoV), has recently been discovered and associated with respiratory disease in small children. However, many patients have presented with low viral DNA loads, suggesting HBoV persistence and rendering polymerase chain reaction-based diagnosis problematic. Moreover, nothing is known of HBoV immunity. We examined HBoV-specific systemic B cell responses and assessed their diagnostic use in young children with respiratory disease. PATIENTS AND METHODS: Paired serum samples from 117 children with acute wheezing, previously studied for 16 respiratory viruses, were tested by immunoblot assays using 2 recombinant HBoV capsid antigens: the unique part of virus protein 1 and virus protein 2. RESULTS: Virus protein 2 was superior to the unique part of virus protein 1 with respect to immunoreactivity. According to the virus protein 2 assay, 24 (49%) of 49 children who were positive for HBoV according to polymerase chain reaction had immunoglobulin (Ig) M antibodies, 36 (73%) had IgG antibodies, and 29 (59%) exhibited IgM antibodies and/or an increase in IgG antibody level. Of 22 patients with an increase in antibody levels, 20 (91%) had a high load of HBoV DNA in the nasopharynx, supporting the hypothesis that a high HBoV DNA load indicates acute primary infection, whereas a low load seems to be of less clinical significance. In a subgroup of patients who were previously determined to have acute HBoV infection (defined as a high virus load in the nasopharynx, viremia, and absence of other viral infections), 9 (100%) of 9 patients had serological evidence of primary infection. In the control group of 68 children with wheezing who had polymerase chain reaction results negative for HBoV in the nasopharynx, 9 (13%) had IgM antibodies, including 5 who displayed an increase in IgG antibody levels and were viremic. No cross-reactivity with human parvovirus B19 was detected. CONCLUSIONS: Respiratory infections due to HBoV are systemic, elicit B cell immune responses, and can be diagnosed serologically. Serological diagnoses correlate with high virus loads in the nasopharynx and with viremia. Serological testing is an accurate tool for disclosing the association of HBoV infection with disease.

Purification and analysis of polyhistidine-tagged human parvovirus B19 VP1 and VP2 expressed in insect cells.

Human parvovirus B19 is an autonomously replicating human pathogen with a specific tropism for human erythroid progenitor cells. There is an interest in producing empty nucleocapsids of B19 as they can be used as tools in molecular biology and diagnostics. Native B19 virus particles are formed from two structural viral proteins, VP1 and VP2. The VP2 protein alone is able to self assemble and consequently form virus-like particles (VLPs) in heterologous expression systems. Purification of recombinant VLPs has been conducted using various traditional methods. These include laborious and time-consuming, e.g. cesium chloride or sucrose gradient ultracentrifugation steps, allowing limited working volumes to be processed. Therefore, an alternative purification method enabling process scale-up was developed and evaluated. Polyhistidine-tagged versions of B19 VP1 and VP2 capsid proteins were engineered and produced using the baculovirus expression system. The recombinant protein products were purified by immobilized metal-ion affinity chromatography (IMAC) and analyzed by SDS-PAGE, immunoblotting, electron microscopy, and enzyme-linked immunosorbent assays. Further, the immunological properties of the recombinant proteins were evaluated. The results showed that the VP2 fusion protein assembled into capsid-like structures and that both VP1 and VP2 following purification by IMAC have potential as antigens for diagnosis of a B19 infection.