Human erythrovirus B19 and blood transfusion ? an update

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.

Detection frequencies and viral load distribution of parvovirus B19 DNA in blood and plasma donations in England

BACKGROUND AND OBJECTIVES

Infections with human parvovirus B19 (B19V) are transmissible by blood components and plasma-derived medicines. The European Pharmacopoeia regulates maximum levels of virus allowed in manufacturers' plasma pools. To evaluate contamination risk prior to re-introduction of UK-sourced plasma for manufacturing, we investigated viraemia frequencies of B19V in plasma samples collected from blood donors before and during COVID-enforced lockdown.

MATERIALS AND METHODS

Quantitative PCR for B19V DNA was used to screen pools of 96 anonymised plasma samples collected in England from 2017 (n = 29 505), 2020 (n = 3360) and 2021 (n = 43 200). Selected positive pools were resolved into individual samples. Data on donor notifications and related lookback investigations were collected from European countries by on-line survey in 2020.

RESULTS

Screening of 76 065 donations identified 80 B19V-positive pools. While most positive samples had low viral loads (<10⁵  IU ml^-1 ), primarily from 2017 (77/29 505; 0.3%), two contained high levels of B19V DNA (1.3 × 10⁸ and 6.3 × 10⁶ IU ml^-1 ), both likely to contaminate a final manufacturer's pool and lead to discard. The incidence of B19V infection during lockdown was reduced (1/3360 in 2020; 0/43 200 in 2021). Genomic analysis of positive pools resolved to single samples identified B19V genotype 1 in all nine samples. Seroprevalence of anti-B19V IgG antibodies was 75% (143/192). A survey of B19V screening practices in Europe demonstrated considerable variability. Two blood establishments informed infected blood donors of positive B19V results.

CONCLUSION

Information on seroprevalence, incidence and viral loads of B19V viraemia is contributory the evaluation of alternative operational screening strategies for plasma testing.

A Conserved Receptor-Binding Domain in the VP1u of Primate Erythroparvoviruses Determines the Marked Tropism for Erythroid Cells

Parvovirus B19 (B19V) is a human pathogen with a marked tropism for erythroid progenitor cells (EPCs). The N-terminal of the VP1 unique region (VP1u) contains a receptor-binding domain (RBD), which mediates virus uptake through interaction with an as-yet-unknown receptor (VP1uR). Considering the central role of VP1uR in the virus tropism, we sought to investigate its expression profile in multiple cell types. To this end, we established a PP7 bacteriophage-VP1u bioconjugate, sharing the size and VP1u composition of native B19V capsids. The suitability of the PP7-VP1u construct as a specific and sensitive VP1uR expression marker was validated in competition assays with B19V and recombinant VP1u. VP1uR expression was exclusively detected in erythroid cells and cells reprogrammed towards the erythroid lineage. Sequence alignment and in silico protein structure prediction of the N-terminal of VP1u (N-VP1u) from B19V and other primate erythroparvoviruses (simian, rhesus, and pig-tailed) revealed a similar structure characterized by a fold of three or four α-helices. Functional studies with simian parvovirus confirmed the presence of a conserved RBD in the N-VP1u, mediating virus internalization into human erythroid cells. In summary, this study confirms the exclusive association of VP1uR expression with cells of the erythroid lineage. The presence of an analogous RBD in the VP1u from non-human primate erythroparvoviruses emphasizes their parallel evolutionary trait and zoonotic potential.

The detection, treatment of parvovirus B19 infection induced anemia in solid organ transplants: a case series and literature review of 194 patients

BACKGROUND

There are no optimal diagnostic, treatment and post-infection surveillance strategies for parvovirus B19 infection in solid organ transplantation (SOT) recipients.

METHODS

We conducted a retrospective review of all PVB19 infected cases confirmed by qPCR among SOT recipients at our institution over a 3-year period and reviewed the literature from 1990 to 2021.

RESULTS

Eight kidney and two heart transplant patients with refractory anemia had PVB19 infection. The viral DNA load in peripheral blood ranged from 2.62 × 10² to 8.31 × 10⁶ copies/mL. Two patients with the lowest PVB19 DNA load only reduced the use of immunosuppressants and anemia was relieved. Eight received intravenous immunoglobulin (IVIG) (ranging from 0.25 to 0.5 g/kg/day). The median time to anemia improvement (hemoglobulin>100g/L) was 16 days (8-70 days) after treatment. One patient had a PVB19 relapse and viral DNA load > 1.00 × 10⁸ copies/mL at diagnosis. A total of 86 studies involving 194 SOTs were screened from the literature, and the most common symptom was anemia and low reticulocyte count. PVB19 DNA was detected in all cases. Of that, 91.4% of cases received IVIG, 53.8% received IVIG and immunosuppression reduction, 6.5% of cases showed reduced immunosuppression without IVIG, and 2.1% did not receive any special treatment. The recurrence rate was 17.5%.

CONCLUSION

PVB19 infection is a cause of anemia after SOT, and treatment mainly relies on IVIG and/or immunosuppression reduction.

Prevalence and Phylogenetic Analysis of Parvovirus (B19V) among Blood Donors with Different Nationalities Residing in Qatar

Human parvovirus (B19V) is the causative agent of erythema infectiosum in children and is linked to a wide range of clinical manifestations. Studies related to B19V prevalence in the Middle East and North Africa (MENA) region and other parts of Asia are very scarce. The objectives of this study were to estimate the seroprevalence (anti-B19V IgM and IgG), the viremia rate (B19V DNA), and the circulating genotypes of B19V among blood donors in Qatar. Methods: Donors’ blood samples (n = 5026) from different nationalities, mainly from the MENA region and South East Asia, were collected from 2014–2016. Samples were tested for the B19V DNA using RT-PCR. Furthermore, 1000 selected samples were tested to determine the seroprevalence of B19V antibodies using enzyme-linked immunosorbent assay (ELISA). Genotyping was performed on 65 DNA positive samples by sequencing of nested PCR fragments (NS1-VP1u region, 927 nt). Results: Only 1.4% (70/5026) of the samples had detectible B19V DNA in their blood. B19V DNA prevalence statistically decreased with age (p = 0.03). Anti-B19V IgG was detected in 60.3% (561/930) of the tested samples, while only 2.1% (20/930) were IgM-positive and 1.2% (11/930) were both IgM- and IgG-positive. B19V genotyping showed a predominance of Genotype 1 (100%). Sequence analysis of the NS1-VP1u region revealed 139 mutation sites, some of which were amino acid substitutions. Conclusion: Our results indicated a relatively high seroprevalence of B19V in Qatar. Most importantly, B19 DNA was detected among Qatari and non-Qatari blood donors. Therefore, blood banks in Qatar might need to consider screening for B19V, especially when transfusion is intended for high-risk populations, including immunocompromised patients.

Prevalence and Quantity of Parvovirus B19 DNA Among Blood Donors from a Regional Blood Center in Turkey

OBJECTIVE

Parvovirus B19 causes a range of diseases and morbidity in humans and is transmissible by transfusion of blood, blood components and plasma derivatives. The objective of the study was to investigate the prevalence and quantity of B19 DNA among blood donors.

METHOD

Totally 1053 samples were collected from March to July 2016 at a blood bank for detection of Parvovirus B19 DNA and serological status of blood donors. Testing of the presence of viral DNA was performed by a quantitative real-time PCR with a 101 copies/ml detection limit. All DNA positive and randomly selected 267 samples were tested for the presence of anti-B19 IgM and IgG by ELISA.

RESULTS

Age distribution of donors was between 18-64; mean age was 27 and median was 23. Among the 1053 samples, 5 (0.47%) had PB19 DNA. All PB19 DNA positive donations had both B19 IgM and IgG antibodies. The DNA level for positive donations were between 0.9 × 102 to 3.1 × 104 copies/ml. IgG and IgM were present in 59.9% (160/267) and 0,74% (2/267) respectively among the healthy donors without PB19 DNA.

CONCLUSION

Detected DNA concentration was less than 105 copies/ml. The presence of IgM in low level PB19 DNA positive donors may indicate that there might be a risk in transmission of PB19 to particularly immunosuppressed recipients. The clinical follow-up of blood donation with low level of PB19DNA should be considered to answer the questions about blood safety.

The seroprevalence of parvovirus B19 antibody in blood donors at the National Blood Transfusion Center in Kinshasa

BACKGROUND

Human parvovirus B19 (PVB19) is a cosmopolitan DNA virus transmissible parenterally by blood transfusion. Therefore, the risk of transmission through asymptomatic blood donors should be considered and appropriately managed worldwide. PVB19 screening of blood and blood products for transfusion is not done routinely in the Democratic Republic of Congo (DRC). The main objective of this study was to determine the seroprevalence of PVB19 infection in healthy eligible blood donors in Kinshasa, capital of the DRC, located in the western part of the DRC, and the association of infection with the sociodemographic characteristics of blood donors.

MATERIALS AND METHODS

A total of 360 whole blood donors who attended the National Center of Blood Transfusion were examined for anti-PVB19 IgG and IgM antibodies by using enzyme-linked immunosorbent assay kits. Sociodemographic information was collected on the blood donors. All statistical analyses were performed with SPSS 21.

RESULTS

Among the study group, 289 men and 52 women were infected with PVB19. The mean age was 32.7 ± 9.8 years, 48.6% of donors were positive only for PVB19 IgG antibodies while 40.8% were positive for both IgG and IgM antibodies. In addition, 5.3% were positive only for PVB19 IgM antibodies and so were considered as a potential group of PVB19 transfusion-transmission. PVB19 seropositivity was significantly associated with sex, with a higher prevalence in men. In multivariate analysis, male sex and Tshangu district have emerged as major factors associated to PVB19 seropositivity.

CONCLUSIONS

This research showed that recipients of blood and blood products in Kinshasa are at a high risk (5.3%) of transfusion-transmitted PVB19 infection. Therefore, the implementation of PVB19 nucleic acid testing assays capable of detecting all PVB19 genotypes and discard donations with high titer PVB19 DNA for blood products seems to be necessary.

An assessment of the risk, cost-effectiveness, and perceived benefits of anti-parvovirus B19 tested blood products

BACKGROUND

Parvovirus B19 (B19V) can cause severe anemia, hydrops foetalis, and even death in vulnerable patients. To prevent transfusion-transmitted B19V infection of at-risk patients, B19V antibody screening of blood donors was implemented. The cost-effectiveness of this intervention is unclear, as the likelihood of transmission through blood and subsequent complications for recipients are unknown. This study estimates the cost-effectiveness of anti-B19V donor screening in the Netherlands.

STUDY DESIGN AND METHODS

The estimates needed for the cost-effectiveness model were: the occurrence of B19V in Dutch blood donors, the number of anti-B19V tested products required by hospitals, the likelihood of morbidity and mortality given B19V infection, treatment costs, and screening costs. These estimates were obtained from literature and observational data. When data were unavailable, structured expert judgment elicitation and statistical modeling were applied.

RESULTS

The costs of preventing one transfusion transmitted B19V infection are estimated at €68,942 (€42,045 - €102,080). On average, 1.25 cases of morbidity and 0.12 cases of mortality are prevented annually. Although the perceived risk of transfusion transmitted B19V infection was low, half of the treating physicians favored anti-B19V screening.

CONCLUSION

The estimated mortality and morbidity caused by B19V infection was low in the risk groups. The cost-effectiveness ratio is similar to other blood safety screening measures. No guidance exists to evaluate the acceptability of this ratio. The explicit overview of costs and effects may further guide the discussion of the desirability of B19V safe blood products.

Human parvovirus B19 in solid organ transplantation: Guidelines from the American society of transplantation infectious diseases community of practice

Clinical manifestations of human parvovirus B19 infection can vary widely and may be atypical in solid organ transplant (SOT) recipients. However, disease is apparent when there is destruction of erythrocyte progenitor cells leading to severe acute or chronic anemia with lack of an appropriate reticulocyte response in the setting of active parvovirus B19 infection. Serology may not reliably establish the diagnosis. High-level viremia is more likely to be associated with symptomatic disease. Conversely, ongoing DNAemia after infection may not be clinically significant, if detected at low levels. Despite lack of robust data, intravenous immunoglobulin (IVIG) is frequently used for the treatment of SOT recipients with symptomatic parvovirus B19 infection. Although the optimal dosage and duration of IVIG is not known, most patients receive a total of 2 g/kg over a period of 2-5 days. A daily dose of 1 g/kg or more seems to be associated with higher incidence of toxicity. Application of standard and droplet isolation precautions remains the cornerstone for preventing human parvovirus B19 transmission. Additional research is needed to assess the efficacy of current and novel therapies and to develop a safe and effective parvovirus B19 vaccine.

Parvovirus B19 in South African blood donors

BACKGROUND

Parvovirus B19 (PVB19) is transmitted via transfusion of blood and blood products. PVB19 is resistant to viral inactivation methods, which poses a threat to blood safety. We investigated the prevalence of PVB19 antibodies and DNA in healthy blood donors from the South African National Blood Bank Service to evaluate the necessity of PVB19 DNA testing.

STUDY DESIGN AND METHOD

A retrospective analysis of 1500 residual plasma specimens from healthy blood donors from the SANBS repository were screened in mini-pools of 20 for PVB19 DNA using a quantitative polymerase chain reaction (PCR). Positive pools were resolved by individual viral load testing and screened for PVB19 immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies to correlate viral loads with serological status. PVB19 IgG prevalence was determined by testing 90 randomly selected specimens from the 1500 plasma specimens.

RESULTS

The prevalence of PVB19 IgG, IgM and IgG, and DNA was 62.2%, 0.06%, and 0.9%, respectively. Fourteen of the 1500 blood donor specimens received, had detectable PVB19 viral loads. Nine of the fourteen donors with detectable viral loads were PVB19 IgG seropositive. The PVB19 viral loads ranged from 1.81 to 5.32 log IU/mL. Four of the fourteen viraemic donors had a viraemia >10 ⁴ IU/mL.

CONCLUSION

We have demonstrated a low prevalence of PVB19 DNA in SANBS blood donors. The predominance of low-level viraemia and the presence of PVB19 antibodies, suggests that the risk of transfusion transmission of PVB19 among SANBS donors may be relatively low.

Seroprevalence of antibodies to primate erythroparvovirus 1 (B19V) in Australia

Backgroud

Primate erythroparvovirus 1 (B19V) is a globally ubiquitous DNA virus. Infection results in a variety of clinical presentations including erythema infectiosum in children and arthralgia in adults. There is limited understanding of the seroprevalence of B19V antibodies in the Australian population and therefore of population-wide immunity. This study aimed to investigate the seroprevalence of B19V antibodies in an Australian blood donor cohort, along with a cohort from a paediatric population.

Methods

Age/sex/geographical location stratified plasma samples (n = 2221) were collected from Australian blood donors. Samples were also sourced from paediatric patients (n = 223) in Queensland. All samples were screened for B19V IgG using an indirect- enzyme-linked immunosorbent assay.

Results

Overall, 57.90% (95% CI: 55.94%–59.85%) of samples tested positive for B19V IgG, with the national age-standardized seroprevalence of B19V exposure in Australians aged 0 to 79 years estimated to be 54.41%. Increasing age (p < 0.001) and state of residence (p < 0.001) were independently associated with B19V exposure in blood donors, with the highest rates in donors from Tasmania (71.88%, 95% CI: 66.95%–76.80%) and donors aged 65–80 years (78.41%, 95% CI: 74.11%–82.71%). A seroprevalence of 52.04% (95% CI: 47.92%–56.15%) was reported in women of child-bearing age (16 to 44 years). Sex was not associated with exposure in blood donors (p = 0.547) or in children (p = 0.261) screened in this study.

Conclusions

This study highlights a clear association between B19V exposure and increasing age, with over half of the Australian population likely to be immune to this virus. Differences in seroprevalence were also observed in donors residing in different states, with a higher prevalence reported in those from the southern states. The finding is consistent with previous studies, with higher rates observed in countries with a higher latitude. This study provides much needed insight into the prevalence of B19V exposure in the Australian population, which has implications for public health as well as transfusion and transplantation safety in Australia.

Ultraviolet C light efficiently inactivates nonenveloped hepatitis A virus and feline calicivirus in platelet concentrates

BACKGROUND

Nonenveloped transfusion-transmissible viruses such as hepatitis A virus (HAV) and hepatitis E virus (HEV) are resistant to many of the common virus inactivation procedures for blood products. This study investigated the pathogen inactivation (PI) efficacy of the THERAFLEX UV-Platelets system against two nonenveloped viruses: HAV and feline calicivirus (FCV), in platelet concentrates (PCs).

STUDY DESIGN AND METHODS

PCs in additive solution were spiked with high titers of cell culture-derived HAV and FCV, and treated with ultraviolet C at various doses. Pre- and posttreatment samples were taken and the level of viral infectivity determined at each dose. For some samples, large-volume plating was performed to improve the detection limit of the virus assay.

RESULTS

THERAFLEX UV-Platelets reduced HAV titers in PCs to the limit of detection, resulting in a virus reduction factor of greater than 4.2 log steps, and reduced FCV infectivity in PCs by 3.0 ± 0.2 log steps.

CONCLUSIONS

THERAFLEX UV-Platelets effectively inactivates HAV and FCV in platelet units.

Parvovirus B19: What Is the Relevance in Transfusion Medicine?

Parvovirus B19 (B19V) has been discovered in 1975. The association with a disease was unclear in the first time after the discovery of B19V, but meanwhile, the usually droplet transmitted B19V is known as the infectious agent of the “fifth disease,” a rather harmless children’s illness. But B19V infects erythrocyte progenitor cells and thus, acute B19V infection in patients with a high erythrocyte turnover may lead to a life-threatening aplastic crisis, and acutely infected pregnant women can transmit B19V to their unborn child, resulting in a hydrops fetalis and fetal death. However, in many adults, B19V infection goes unnoticed and thus many blood donors donate blood despite the infection. The B19V infection does not impair the blood cell counts in healthy blood donors, but after the acute infection with extremely high DNA concentrations exceeding 10¹⁰ IU B19V DNA/ml plasma is resolved, B19V DNA persists in the plasma of blood donors at low levels for several years. That way, many consecutive donations that contain B19V DNA can be taken from a single donor, but the majority of blood products from donors with detectable B19V DNA seem not to be infectious for the recipients from several reasons: first, many recipients had undergone a B19V infection in the past and have formed protective antibodies. Second, B19V DNA concentration in the blood product is often too low to infect the recipient. Third, after the acute infection, the presence of B19V DNA in the donor is accompanied by presumably neutralizing antibodies which are protective also for the recipient of his blood products. Thus, transfusion-transmitted (TT-) B19V infections are very rarely reported. Moreover, in most blood donors, B19V DNA concentration is below 1,000 IU/ml plasma, and no TT-B19V infections have been found by such low-viremic donations. Cutoff for an assay for B19V DNA blood donor screening should, therefore, be approximately 1,000 IU/ml plasma, if a general screening of blood donors for single donation blood components is considered at all: for the overwhelming majority of transfusion recipients, B19V infection is not relevant as well as for the blood donors. B19V DNA screening of vulnerable patients after transfusion seems to be a more reasonable approach than general blood donor screening.

Parvovirus B19 in the Context of Hematopoietic Stem Cell Transplantation: Evaluating Cell Donors and Recipients

Background

Parvovirus B19 (B19V) is a common human pathogen, member of the family Parvoviridae. Typically, B19V has been found to infect erythroid progenitors and cause hematological disorders, such as anemia and aplastic crisis. However, the persistence of genomic deoxyribonucleic acid (DNA) has been demonstrated in tonsils, liver, skin, brain, synovial, and testicular tissues as well as bone marrow, for both symptomatic and asymptomatic subjects. Although the molecular and cellular mechanisms of persistence remain undefined, it raises questions about potential virus transmissibility and its effects in the context of allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients.

Methods

With this aim, we retrospectively screened allogeneic stem cell donors from 173 patients admitted for allo-HSCT from January 2008 to May 2013 using a seminested polymerase chain reaction approach.

Results

We found 8 positive donor samples, yielding a 4.6% of parvovirus prevalence (95% confidence interval, 2.36-8.85). Pre- and post-HSCT samples (n = 51) from the 8 recipients of the positive donors were also investigated, and 1 case exhibited B19V DNA in the post-HSCT follow-up (D + 60). Direct DNA sequencing was performed to determine the genotype of isolates and classification, performed by phylogenetic reconstruction, showed a predominance of genotype 1a, whereas the rare genotype 3b was detected in 2 additional patients. By molecular cloning, different B19V 1a substrains polymorphisms were evidenced in the single case in which donor and its recipient were B19V+.

Conclusions

Our results suggest that HSCT allografts are not a main source for B19V transmission, pointing to potential events of reinfection or endogenous viral reactivation.

A new protoparvovirus in human fecal samples and cutaneous T cell lymphomas (mycosis fungoides)

We genetically characterized seven nearly complete genomes in the protoparvovirus genus from the feces of children with diarrhea. The viruses, provisionally named cutaviruses (CutaV), varied by 1-6% nucleotides and shared ~76% and ~82% amino acid identity with the NS1 and VP1 of human bufaviruses, their closest relatives. Using PCR, cutavirus DNA was found in 1.6% (4/245) and 1% (1/100) of diarrhea samples from Brazil and Botswana respectively. In silico analysis of pre-existing metagenomics datasets then revealed closely related parvovirus genomes in skin biopsies from patients with epidermotropic cutaneous T-cell lymphoma (CTCL or mycosis fungoides). PCR of skin biopsies yielded cutavirus DNA in 4/17 CTCL, 0/10 skin carcinoma, and 0/21 normal or noncancerous skin biopsies. In situ hybridization of CTCL skin biopsies detected viral genome within rare individual cells in regions of neoplastic infiltrations. The influence of cutavirus infection on human enteric functions and possible oncolytic role in CTCL progression remain to be determined.

Parvovirus B19 Passive Transmission by Transfusion of Intercept® Blood System-Treated Platelet Concentrate

BACKGROUND

Pathogen reduction methods for blood components are effective for a large number of viruses though less against small, non-enveloped viruses such as Parvovirus B19 (B19V). This article describes the passive transmission by transfusion of two B19V-contaminated pooled platelet concentrates (PCs) which were treated with the Intercept® blood pathogen reduction system.

CASE REPORTS

Two transfusion cases of B19V-contaminated Intercept-treated pooled PCs were described. Due to the analysis delay, the PCs were already transfused. The viral content of each donation was 4.87 × 10(10) IU/ml in case 1and 1.46 × 10(8) IU/ml in case 2. B19V (52 IU/ml) was detected in the recipient of the case 1 PC, whereas no virus could be detected in the case 2 PC recipient. A B19V IgM response and a transient boost of the underlying B19V IgG immune status and was observed in recipient 1. Recipient of the case 2 PC remained B19V IgG- and IgM-negative. B19V DNA sequence and phylogenetic analysis revealed a 100% homology between donor and recipient.

CONCLUSION

This report describes passive B19V transmission by a PC with very high B19 viral load which elicited a transient boost of the B19V immunity, but not by a PC with a lower B19V content, suggesting that there is a B19 viral load threshold value at which B19V inactivation is exceeded.

Validation of new real-time polymerase chain reaction assays for detection of hepatitis A virus RNA and parvovirus B19 DNA

BACKGROUND

To meet European guidelines for plasma for fractionation, plasma fractionators have implemented parvovirus B19 (B19V) and hepatitis A virus (HAV) nucleic acid test (NAT) screening on test pools. In this study we evaluate recently developed in-house NAT assays for B19V DNA and HAV RNA. The B19V NAT was designed to target two different regions of the B19V genome.

STUDY DESIGN AND METHODS

The B19V DNA and HAV RNA tests were validated according to commonly used guidelines. The performance of the B19V and HAV assays was evaluated during routine screening of more than 2 × 10(6) donations.

RESULTS

The 95% lower limit of detection (LLD) of the HAV NAT was 1.34 IU/mL. The 95% LLD for B19V was 39.1 IU/mL for the NS1 region and 76.9 IU/mL for the VP2 region. The B19V test showed good accuracy, precision, robustness, and no cross-contamination was observed. Both assays detected B19V Genotypes 1 to 3 and HAV Genotypes I to III. During routine screening 103 donations showed B19V DNA loads of more than 1.25 × 10(6) IU/mL and one donation was reactive in the HAV NAT.

CONCLUSION

The dual-target B19V polymerase chain reaction (PCR) showed good accuracy (<0.1 log IU/mL) at the crucial concentration of 10 IU/µL for the NS1 and the VP2 region of the B19V genome and detected all known genotypes with similar sensitivity for each genotype. In addition, the dual target format reduces the chance that molecular variants of B19V are wrongly quantified. The HAV RNA assay showed high sensitivity for Genotypes I to III. Both new PCR assays have been successfully introduced for plasma screening in test pools of 480 or 96 donations.

Look-back study on recipients of Parvovirus B19 (B19V) DNA-positive blood components

BACKGROUND AND OBJECTIVES

To assess the relevance of Parvovirus B19 (B19V) DNA at low to intermediate concentrations in blood donors for the recipients of their blood components.

MATERIAL AND METHODS

We studied recipients of B19V DNA-positive blood components [red blood cell concentrates (RBCs), pooled platelet concentrates and fresh frozen plasma]. This included archived pretransfusion samples as well as follow-up samples investigated by ELISA or NAT and genome sequence analysis.

RESULTS

In 132 out of 424 recipients, we could detect no anti-B19V IgG before transfusion. In 67 out of 132 sero-negative recipients, a follow-up sample was available. Sixty-five of these received blood components from donors with <10(4) IU B19V DNA/ml plasma and had no evidence of transfusion-transmitted (TT)-B19V infection. Homology in genome sequences in donor and recipient provided evidence for a TT-B19V infection in two recipients. Both patients received RBC containing 3.4 × 10(6) and 1.8 × 10(4) IU B19V DNA/ml plasma, respectively. The anti-B19V IgG titres in the donors were 2 and 76 IU/ml plasma, respectively. The antibodies in the second donor were directed against capsid proteins and are thus considered as potential neutralizing antibodies.

CONCLUSIONS

TT-B19V infections through blood components with low (<10(4) IU/ml plasma) B19V DNA concentrations did not occur in our study. One of the TT-B19V infections occurred from RBC with intermediate B19V DNA concentration despite the presence of potential neutralizing antibodies in the donor, but its clinical significance was low.

Characterization of Markers of the Progression of Human Parvovirus B19 Infection in Virus DNA-Positive Plasma Samples

BACKGROUND

Accurate characterization of the infection stage in parvovirus B19(B19V)-positive plasma donations would help establish the donation deferral period to contribute to a safe fractionation pool of plasma.

METHODS

Viral DNA load of 74 B19V DNA-positive plasma samples from whole blood donations was determined by titration using nucleic acid testing. Markers of cellular (neopterin) and humoral (B19V-specific IgM and IgG) immune response were determined by ELISA in 32 B19V DNA-positive samples and in 13 B19V DNA-negative samples. The infection progression profile was estimated according to B19V DNA load and the presence of immune response markers.

RESULTS

B19V DNA load in the 74 samples was 10(6)-10(13) IU/ml. The distribution of 14 out of 32 selected B19V DNA-positive samples plus 2 B19V DNA-negative samples with no immune response marker followed along an upward curve according to B19V DNA load. After the peak, the distribution of 18 immune marker-positive samples followed along a downward curve according to their B19V DNA load and was grouped as follows: neopterin (n = 4), neopterin+ IgM (n = 8), neopterin + IgM + IgG (n = 3), IgM + IgG (n = 2), IgM (n = 1). There were 11 B19V DNA-negative IgG-positive samples.

CONCLUSION

This study of B19V-DNA load and levels of neopterin, IgM, and IgG allows for reliable characterization and distribution into the different stages of B19V infection.

Large animal evaluation of riboflavin and ultraviolet light-treated whole blood transfusion in a diffuse, nonsurgical bleeding porcine model

BACKGROUND

The Mirasol system has been demonstrated to effectively inactivate white blood cells (WBCs) and reduce pathogens in whole blood in vitro. The purpose of this study was to compare the safety and efficacy of Mirasol-treated fresh whole blood (FWB) to untreated FWB in an in vivo model of surgical bleeding.

STUDY DESIGN AND METHODS

A total of 18 anesthetized pigs (40 kg) underwent a 35% total blood volume bleed, cooling to 33°C, and a standardized liver injury. Animals were then randomly assigned to resuscitation with either Mirasol-treated or untreated FWB, and intraoperative blood loss was measured. After abdominal closure, the animals were observed for 14 days, after which the animals were euthanized and tissues were obtained for histopathologic examination. Mortality, tissue near-infrared spectroscopy, red blood cell (RBC) variables, platelets (PLTs), WBCs, and coagulation indices were analyzed.

RESULTS

Total intraoperative blood loss was similar in test and control arms (8.3 ± 3.2 mL/kg vs. 7.7 ± 3.9 mL/kg, p = 0.720). All animals survived to Day 14. Trended values over time did not show significant differences-tissue oxygenation (p = 0.605), hemoglobin (p = 0.461), PLTs (p = 0.807), WBCs (p = 0.435), prothrombin time (p = 0.655), activated partial thromboplastin time (p = 0.416), thromboelastography (TEG)-reaction time (p = 0.265), or TEG-clot formation time (p = 0.081). Histopathology did not show significant differences between arms.

CONCLUSIONS

Mirasol-treated FWB did not impact survival, blood loss, tissue oxygen delivery, RBC indices, or coagulation variables in a standardized liver injury model. These data suggest that Mirasol-treated FWB is both safe and efficacious in vivo.

Persistence of Parvovirus B19 (B19V) DNA and humoral immune response in B19V-infected blood donors

BACKGROUND AND OBJECTIVES

Parvovirus B19 (B19V) DNA seems to persist in the plasma of B19V-infected blood donors. The relevance of this for recipients of single-donor blood components is yet unclear.

MATERIAL AND METHODS

We studied serial archive and follow-up samples from 75 B19V-infected blood donors to obtain more data about the duration and degree of viraemia and the presence of IgG and IgM anti-B19V. IgG antibodies were further characterized by Western blot analysis in 29 donors.

RESULTS

In 411 B19V DNA-positive samples collected, we found high concentrations (>10(6) IU B19V DNA/ml plasma) in five. B19V DNA persisted for a mean of 21·5 months (range: 2·3-52·4; 95% confidence interval, 19·1-23·9 months) in all donors. Only 15 such samples had either no or low-titre IgG anti-B19V. IgG antibodies were predominantly directed against epitopes on the minor capsid protein VP1, thus probably of neutralizing type with high avidity. IgM anti-B19V was detectable in 9/13 samples with high DNA concentrations.

CONCLUSIONS

The vast majority of single-donor blood components with detectable B19V DNA are probably not infectious for their recipients because DNA is at only low levels and the donors also have potentially neutralizing antibodies with high avidity. Anti-B19V IgM testing does not identify every donation with high B19V DNA concentrations, but, in addition to B19V NAT testing, donors with persistent IgG anti-B19V might be considered 'B19V-safe' for single-donor blood components.

Parvovirus b19 infections and blood counts in blood donors

OBJECTIVES

Parvovirus B19 (B19V) is a transfusion-transmissible virus. To obtain data about the prevalence, incidence, the course of B19V infection in blood donors and whether B19V might impair their blood counts, samples from blood donors with B19V infection were investigated.

METHODS

Blood donations were screened for B19V DNA using the Cobas TaqScreen DPX Test® in mini-pools. B19V DNA concentration, anti-B19V IgG antibody titer and blood counts were determined in positive donors.

RESULTS

157/23,889 (0.66%) donors provided 347 B19V DNA-positive samples. Prevalence of B19V infection was 0.45%, incidence 0.20%. B19V DNA concentrations were predominantly low; only in 8 samples were viral loads of ≥10(5) IU B19V DNA/ml plasma detectable. Besides a slight decrease in hemoglobin, hematocrit, mean corpuscular volume, mean cellular hemoglobin and mean hemoglobin concentration, no major differences in blood counts occurred in B19V DNA-positive samples. In samples with a low B19V DNA concentration, anti-B19V IgG titers were rather high. 98 donors provided at least 1 B19V DNA-positive follow-up sample, indicating a prolonged viremia.

CONCLUSIONS

B19V infection induced no major impairment in the blood counts. In donors with low-level viremia, infectivity through their donations is probably reduced by high antibody titers. Low-level viremia is prolonged, probably exceeding 1 year in many cases.

Keeping pace with parvovirus B19 genetic variability: a multiplex genotype-specific quantitative PCR assay

Three genotypes have been identified within the parvovirus B19 species (B19V), and such genetic diversity may have significant implications for the development of molecular detection assays. In the present study, B19V genetic variability has been examined on a subset of genomic sequences available in the NCBI nucleotide database, and a quantitative PCR (qPCR) assay able to detect, differentiate, and quantify all viral variants has been established. The designed primers and probes have been used for the development of alternative detection formats, based on a combined use of intercalating dye and genotype-specific hydrolysis probes. The qPCR assay analytical performances have been determined on the 1st WHO International Reference Panel for Parvovirus B19 Genotypes. The developed qPCR protocols allow for the detection of genotypes 1 to 3 with equal accuracy, and with a limit of detection (LOD) of 200 IU/ml. A comparison of routine performance was carried out with respect to a previously established assay specifically validated on B19V genotype 1. For 130 clinical samples analyzed, 126 showed concordant results (31 positive and 97 negative), while 4 showed discordant results. Overall, the genotype-specific qPCR assay showed a sensitivity of 93.94% and a specificity of 97.94%, with an agreement rate of 96.92%. The proposed qPCR assay and the alternative protocols developed, each with robust performance, may allow choice with respect to operational systems and diagnostic requirements and might contribute to provide a more reliable diagnostic service and epidemiological surveillance of B19 virus.

Prevalence of human parvovirus B19, bocavirus, and PARV4 in blood samples from the general population of China and lack of a correlation between parvovirus and hepatitis B co-infection

Few comprehensive studies have investigated viraemia caused by human parvoviruses (HPAVs) in China. A total of 1626 of blood samples were collected from non-HBV and HBV infected Chinese subjects (adults, N = 1279; children, N = 347) from south-western and south-eastern China. DNA from three HPAVs was detected in blood samples using PCR-based assays. The epidemiological profiles and association with HBV co-infection were also analysed. Of the 1626 blood samples tested, 138 (8.49%) were found to exhibit HPAV viraemia, including 3.51% with B19, 3.75% with HBoV and 2.52% with PARV4. The presence of B19 DNA in both child and adult, as well as that of PARV4 DNA in adult,from the south-western region was significantly higher than that from the south-eastern region (P = 0.006 for B19 in children; P = 0.026 for B19 in adults; and P = 0.014 for PARV4 in adult).However, the frequency of HBoV DNA in adults from the south-western region was significantly lower than that observed in adults from the south-eastern region (P = 0.001). Furthermore, HBoV was more prevalence in male (4.9%) than in female (1.4%) individuals. In addition, no significant correlation between HBV and HPAV co-infection was found using serum samples from Chinese adults. In conclusions,the molecular prevalence of three HPAVs in blood samples exhibited variation among different populations depending on area, age and gender; No association between HPAV and HBV infection in adults was found. Our data provide a basis for improving blood safety and preventing HPAV infection in China.

Parvovirus B19 Achievements and Challenges

Parvovirus B19 is a widespread human pathogenic virus, member of the Erythrovirus genus in the Parvoviridae family. Infection can be associated with an ample range of pathologies and clinical manifestations, whose characteristics and outcomes depend on the interplay between the pathogenetic potential of the virus, its adaptation to different cellular environments, and the physiological and immune status of the infected individuals. The scope of this review is the advances in knowledge on the biological characteristics of the virus and of virus-host relationships; in particular, the interactions of the virus with different cellular environments in terms of tropism and ability to achieve a productive replicative cycle, or, on the contrary, to establish persistence; the consequences of infection in terms of interference with the cell physiology; the process of recognition of the virus by the innate or adaptive immune system, hence the role of the immune system in controlling the infection or in the development of clinical manifestations. Linked to these issues is the continuous effort to develop better diagnostic algorithms and methods and the need for development of prophylactic and therapeutic options for B19V infections.

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

Background

Parvovirus 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 presentation

Herein 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.

Conclusion

This 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.

Transfusion issues in cancer patients

Allogeneic blood transfusion (ABT) therapy plays a major role in the case of patients with cancer. Packed red blood cells (PRBC) are given for increased oxygen-carrying capacity, platelets concentrates (PC) and fresh frozen plasma (FFP) for the cessation and prevention of bleeding due to thrombocytopenia and other defects of hemostasis associated with neoplasia. All these blood components can induce complications and/or adverse reactions in cancer patients including transfusion-associated graft versus host disease (TA-GVHD), transfusion transmitted diseases, alloimmunization to blood cell antigens, pulmonary decompensation, immunomodulation. Therefore, specific modifications such as leukocyte-reduction and irradiation of the blood components to be transfused in cancer patients should be introduced to reduce the risk of these complications. Patients undergoing hematopoietic progenitor cell (HPC) transplantation are a unique group and present complex concerns related to transfusion, including major and minor ABO incompatibility and chimeric blood cells. Therefore, transfusion for patients undergoing treatment with cellular therapies requires careful blood component selection. The process of HPC infusion itself carries many risks including DMSO toxicity and hemolytic reactions. In all areas of transfusion therapy, new advances such as pathogen inactivation and synthetic alternatives to blood components should help to increase the safety and tolerance of transfusion in cancer patients.

Parvovirus B19V DNA contamination in Chinese plasma and plasma derivatives

Background

To ensure the safety of plasma derivatives, screening for human parvovirus B19V genomic DNA in donated plasma using a pooling strategy is performed in some countries. We investigated the prevalence of B19V DNA and anti-B19V antibodies in Chinese plasma pools, plasma derivatives and plasma donations to evaluate the risk posed by B19V.

Methods

Using a Q-PCR assay developed in-house, we tested for B19V genomic DNA in 142 plasma pools collected between January 2009 and June 2011 from two Chinese blood products manufacturers. Plasma derivatives collected between 1993–1995 (10 batches of albumin, 155 batches of intravenous immunoglobulin, IVIG) and 2009–2011 (50 batches of albumin, 54 batches of IVIG, 35 batches of factor VIII, 7 batches of fibrinogen, and 17 batches of prothrombin complex concentrate, PCC) were also tested for B19V contamination. In addition, B19V genome prevalence in minipools(including 90 individual donations) of 49680 individual plasma samples collected between August 2011 and March 2012 by a single Chinese manufacturer was investigated. IgM/IgG was also investigated in plasma pools/derivatives and in minipools with B19V-DNA titers above 1x10⁴ and 1x10⁶ geq/mL using B19 ELISA IgM/IgG assay(Virion-Serion, Würzburg, Germany), respectively.

Results

B19V-DNA was detected in 54.2% of plasma pools from two Chinese blood product manufacturers; among recently produced blood products, B19V was detected in 21/54 IVIG samples, 19/35 factor VIII samples, 6/7 fibrinogen samples, and 12/17 PCC samples, but not in albumin samples. The levels of B19V-DNA in these samples varied from 10²-10⁷ geq/mL. In samples with >10⁴ geq/mL genome DNA, B19V-specific IgG was also found in all corresponding plasma pools and IVIG, whereas none was detected in the majority of other plasma derivatives. Screening of plasma donations indicated that most minipools were contaminated with B19V-DNA (10²-10⁸ geq/mL) and one donation had 1.09 × 10¹⁰ geq/mL B19V genomic DNA along with a non-classical IgG/IgM profile.

Conclusions

Despite the implementation of some inactivation/removal methods designed to prevent viral contamination, B19V DNA was detectable in Chinese plasma pools and plasma derivatives. Thus, the introduction of B19V screening and discard donation with high viramic concentration for Chinese plasma donors would be desirable.

Global co-existence of two evolutionary lineages of parvovirus B19 1a, different in genome-wide synonymous positions

Parvovirus B19 (B19V) can cause infection in humans. To date, three genotypes of B19V, with subtypes, are known, of which genotype 1a is the most prevalent genotype in the Western world. We sequenced the genome of B19V strains of 65 asymptomatic, recently infected Dutch blood donors, to investigate the spatio-temporal distribution of B19V strains, in the years 2003-2009. The sequences were compared to B19V sequences from Dutch patients with fifth disease, and to global B19V sequences as available from GenBank. All Dutch B19V strains belonged to genotype 1a. Phylogenetic analysis of the strains from Dutch blood donors showed that two groups of genotype 1a co-exist. A clear-cut division into the two groups was also found among the B19V strains from Dutch patients, and among the B19V sequences in GenBank. The two groups of genotype 1a co-exist around the world and do not appear to differ in their ability to cause disease. Strikingly, the two groups of B19V predominantly differ in synonymous mutations, distributed throughout the entire genome of B19V. We propose to call the two groups of B19V genotype 1a respectively subtype 1a1 and 1a2.

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.

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.

Collaborative study to establish a World Health Organization International genotype panel for parvovirus B19 DNA nucleic acid amplification technology (NAT)-based assays

BACKGROUND AND OBJECTIVES

The aim of the collaborative study was to evaluate a panel of plasma samples containing different genotypes of parvovirus B19 (B19V) for use in nucleic acid amplification technology (NAT)-based assays.

MATERIALS AND METHODS

The panel of samples [Center for Biologics Evaluation and Research Parvovirus B19 Genotype Panel 1; National Institute for Biological Standards and Control (NIBSC) code number 09/110] comprises four different members, i.e. Member 1, Member 2, Member 3, and Member 4 (M1-M4); these represent genotypes 1, 2, 3a B19V, and a negative plasma control, respectively. Thirty-five laboratories from 13 different countries participated in the study. Participants assayed the panel members concurrently with the 2nd World Health Organization (WHO) International Standard for B19V DNA (NIBSC code 99/802) on four separate occasions.

RESULTS

A total of 44 sets of data were returned, 34 from quantitative assays and 10 from qualitative assays. The majority of assays used were in-house and based on real-time PCR. The results showed that all three genotypes were detected consistently by the majority of participants, although a small number of assays detected genotypes 2 and 3 less efficiently, or not at all. Real-time stability studies have indicated that the panel of B19V samples is stable under normal conditions of storage, i.e. ≤-70°C.

CONCLUSIONS

The four-member panel is intended for use in evaluating the ability of NAT assays to detect different B19V genotypes (M1-M3). Based on the results of the collaborative study, the panel was established as the 1st WHO International Reference Panel for parvovirus B19 genotypes.

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.

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

BACKGROUND

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.

STUDY DESIGN AND METHODS

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.

RESULTS

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.

CONCLUSIONS

Whether B19 NAT screening of blood and blood products should be launched in China, larger studies are needed to facilitate an informed decision.

Symptomatic parvovirus B19 infection caused by blood component transfusion

BACKGROUND

Although a risk of transfusion-transmitted human parvovirus B19V (TT-B19V) infection has been a concern, there have been very few reports of clinically relevant TT-B19V caused by the transfusion of a B19V-containing blood component. It has therefore been a matter of debate whether a universal B19V screening with an appropriate sensitivity is required.

STUDY DESIGN AND METHODS

Through the Japanese Red Cross hemovigilance system, clinical reports on possible TT-B19V were collected from 1999 to 2008, during which B19V donor screening (sensitivity, 10(10) IU/mL) was conducted and repository blood samples from donors were available.

RESULTS

Eight patients with TT-B19V caused by component transfusion have been identified. Four patients developed sustained anemia and pure red blood cell (RBC) aplasia and one patient developed pancytopenia. The underlying diseases in these five patients were either hematologic malignancy or hemolytic diseases. The viral loads of the responsible components for these cases ranged from 10(3) to 10(8) IU/mL. Two patients who underwent surgical treatment without any hematologic disorder exhibited only moderate symptoms. The B19V DNA sequence identity between a patient and the linked blood donor was confirmed in five of the eight patients. All of the components responsible for the eight cases were positive for anti-B19V immunoglobulin (Ig)M.

CONCLUSION

Vulnerability to serious B19V-related hematologic disorders depended on the patient's underlying disease state of an enhanced erythropoiesis, not on the viral load of the component transfused. To prevent clinically relevant TT-B19V, a strategy is suggested in which patients at risk of acquiring RBC aplasia or pancytopenia are targeted.

Prevalence of nucleic acid sequences specific for human parvoviruses, hepatitis A and hepatitis E viruses in coagulation factor concentrates

BACKGROUND AND OBJECTIVES

Due to their high resistance to inactivation procedures, nonenveloped viruses such as parvovirus B19, human bocavirus (HBoV), human parvovirus 4 (PARV4), hepatitis A (HAV) and hepatitis E virus (HEV) pose a particular threat to blood products. Virus transmission to patients treated with blood products presents an additional burden to disease. We determined the frequency and the amount of nucleic acid specific for nonenveloped viruses in recently manufactured preparations of commercial coagulation factor concentrates.

MATERIALS AND METHODS

At least three different batches of each of 13 different plasma-derived and recombinant coagulation factor products were tested for the presence and the amount of nucleic acid for parvovirus B19, HBoV, human parvovirus 4, hepatitis A virus and HEV by using quantitative polymerase chain reaction.

RESULTS

Whereas none of the recombinant products tested positive for any of these viruses, parvovirus B19 DNA with amounts ranging between 2×10(1) and 1.3×10(3) genome equivalents/ml was detected in five plasma-derived products. In addition to parvovirus B19 genotype 1, genotypes 2 and 3 were observed in two batches of a factor VIII/von-Willebrand factor product. In two products (one factor VIII concentrate and one activated prothrombin complex concentrate), a combination of both genotypes 1 and 2 of parvovirus B19 was detected.

CONCLUSION

The data show that nucleic acids from several relevant nonenveloped viruses are not found at detectable levels in coagulation factor concentrates. In some cases, parvovirus B19 DNA was detectable at low levels. Testing of the plasma pools for the full range of parvovirus genotypes is advocated for ensuring product safety.

Investigation of the prevalence of human parvovirus B19 DNA in Korean plasmapheresis donors

BACKGROUND

To ensure the safety of plasma derivatives, some countries have been screening for the human parvovirus B19 (B19V) antigen or DNA in blood donors. We investigated the prevalence of B19V DNA and anti-B19V antibodies in Korean plasmapheresis donors to evaluate the necessity of B19V DNA screening test.

METHODS

Plasma samples were collected between March and July 2008 from 10,032 plasmapheresis donors. The B19V DNA test was performed using the LightCycler 2.0 (Roche, Germany) with quantification kits. Anti-B19V IgM and IgG were tested in 928 randomly selected samples from the 10,032 donors using recomWell Parvovirus B19 ELISA IgM, IgG assay (Mikrogen, Germany). RecomLine Parvovirus B19 LIA IgG, IgM assay (Mikrogen, Germany) was used to analyze the epitopes of antibodies in donors showing positive results for B19V DNA and anti-B19V antibodies. DNA sequencing was performed to identify the genotypes.

RESULTS

The prevalence of B19V DNA was 0.1% (10/10,032). Virus titers in B19V DNA positive donors were less than 10(5) IU/mL (range: 2.7 x 10(1)-3.2 x 10(4) IU/mL) except for 1 donor (1.33 x 10(8) IU/mL). All the isolated B19V DNAs from 6 donors were identified as genotype I. Nine out of 10 B19V DNA positive donors also possessed anti-B19V IgG only or IgG and IgM. The prevalence of anti-B19V IgG was 60.1% (558/928).

CONCLUSIONS

The prevalence of B19V DNA in Korean blood donors was not high and most donors also possessed neutralizing anti-B19V antibodies. Thus, the implementation of a B19V screening test for Korean blood donors does not appear to be imperative.

[Evaluation of the virus-elimination efficacy of nanofiltration (Viresolve NFP) for the parvovirus B19 and hepatitis A virus]

BACKGROUND

The safety of plasma derivatives has been reinforced since 1980s by variable pathogen inactivation or elimination techniques. Nucleic acid amplification test (NAT) for the source plasma has also been implemented worldwide. Recently nanofiltration has been used in some country for ensuring safety of plasma derivatives to eliminate non-enveloped viruses such as parvovirus B19 (B19V) and hepatitis A virus (HAV). We evaluated the efficacy of nanofiltration for the elimination of B19V and HAV.

METHODS

To verify the efficacy of nanofiltration, we adopted a 20 nm Viresolve NFP (Millipore, USA) in the scaling down (1:1,370) model of the antithrombin III production. As virus stock solutions, we used B19V reactive plasma and porcine parvovirus (PPV) and HAV obtained from cell culture. And 50% tissue culture infectious dose was consumed as infectious dose. The methods used to evaluate the virus-elimination efficacy were reverse-transcriptase polymerase chain reaction for B19V and the cytopathic effect calculation after filtration for PPV and HAV.

RESULTS

B19V was not detected by RT-PCR in the filtered antithrombin III solutions with initial viral load of 6.42 x 10(5) IU/mL and 1.42 x 10(5) IU/mL before filtration. The virus-elimination efficacy of nanofiltration for PPV and HAV were > or = (3.32) and > or = (3.31), respectively.

CONCLUSIONS

Nanofiltration would be an effective method for the elimination of B19V and HAV. It may be used as a substitute for NAT screening of these viruses in source plasma to ensure safety of plasma derivatives in Korea.

The detection of parvoviruses

Parvovirus B19 is a single-stranded DNA virus which causes severe disease in immunocompromised patients and foetal loss in pregnant women. It is classified as an Erythrovirus and this genus also comprises two related viral genotypes (so-called LaLi/A6 (genotype 2) and V9 (genotype 3)) which appear to be immunologically indistinguishable from Parvovirus B19. Serological and nucleic acid test (NAT) systems to detect Parvovirus B19-mediated infection are commercially available; however, some NAT systems are genotype-specific. International standard preparations of Parvovirus B19 IgG and DNA have been produced for assay standardisation purposes, and to ensure consistency of assay manufacture and performance. Immunological assays, such as B-cell ELISpot, T-cell stimulation, and cytokine detection can also be used to confirm exposure to Parvovirus B19. Immunohistochemical techniques, employing commercially available monoclonal antibodies, are used to localise the virus in infected tissue and Parvovirus B19 viral antigen can also be detected in serum and plasma using antigen-specific ELISA. NAT systems have also been described to detect newly identified parvoviruses such as human bocavirus (HBoV), PARV4, and PARV5, although absolute confirmation of clinical diseases associated with these agents is required. This chapter describes the current status of detection systems for all the aforementioned parvoviruses, with particular emphasis on Erythrovirus detection by serological, NAT, and immunological approaches.

Collaborative study to establish a replacement World Health Organization International Standard for parvovirus B19 DNA nucleic acid amplification technology (NAT)-based assays

BACKGROUND AND OBJECTIVES

The aim of the study was to replace the 1(st) World Health Organization International Standard for parvovirus B19 DNA for nucleic acid amplification technique (NAT)-based assays (code 99/800). Two lyophilized preparations (coded 99/800 and 99/802) had been evaluated in the original collaborative study. The present study re-evaluates these two preparations in terms of potency, stability and encapsidation of virus DNA.

MATERIALS AND METHODS

The 1(st) International Standard (99/800) and 99/802 were re-coded as Samples 1 and 2, respectively. The samples were distributed to six laboratories and assayed on four separate occasions. Accelerated thermal degradation samples of the two preparations were examined after storage at 20 degrees C for 7 years. Nuclease treatment was used to investigate the encapsidation of virus DNA.

RESULTS

Data were returned from a total of six different quantitative NAT-based assays. The results of the present study confirm those of the original, with no significant differences found in estimated international units (IU)/ml for the 1(st) International Standard (Sample 1 in this study) and the proposed replacement preparation, Sample 2 (99/802). Accelerated thermal degradation studies demonstrate that both samples are very stable, with no loss of potency after storage at 20 degrees C for 7 years. Both lyophilized preparations contained the majority of B19V DNA encapsidated in virions.

CONCLUSIONS

On the basis of the data presented in this collaborative study, Sample 2 (code number 99/802) was established as the 2(nd) International Standard for parvovirus B19 DNA for NAT-based assays with a potency of 10(6) IU/ml (500 000 IU/vial).