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

Unexpected high incidence of parvovirus B19 nucleic acid detection in German blood donors in the winter/spring season 2023/2024

In healthy adults, parvovirus B19 (PVB19) typically causes mild symptoms but can lead to severe complications in immunosuppressed individuals or those with high red blood cell turnover. Infection can occur through respiratory transmission or via transfusion, necessitating the testing of blood donations in Germany. Between 2015 and April 2024, we screened 2 105 755 blood donations for PVB19 using polymerase chain reaction. Incidence rates were calculated for three periods: pre-COVID-19 (2015-2020), during the pandemic (2020-2023), and post-COVID-19 (2023-2024). A total of 242 PVB19-positive donations were identified. In the first period, there were 101 positives out of 1 228 361 donations (incidence: 0.83/10 000). In the second period, four positives were found out of 621 222 donations (incidence: 0.06/10 000). In the third period, 137 positives were detected out of 235 088 donations (incidence: 5.35/10 000) with a striking increase of incidence between December 2023 and March 2024 (4.3-21.1/10 000 donations). Most people develop lifelong immunity after infection in childhood but the COVID-19 pandemic interventions, like masks and distancing, correlate with a decline in PVB19 infections in donors indicating an impact of hygiene measures on PVB19 infection rates.

Human herpesvirus-6, HHV-8 and parvovirus B19 after allogeneic hematopoietic cell transplant: the lesser-known viral complications

PURPOSE OF REVIEW

Viral infections continue to burden allogeneic hematopoietic cell transplant (HCT) recipients. We review the epidemiology, diagnosis, and management of human herpesvirus (HHV)-6, HHV-8 and parvovirus B19 following HCT.

RECENT FINDINGS

Advances in HCT practices significantly improved outcomes but impact viral epidemiology: post-transplant cyclophosphamide for graft-versus-host disease prevention increases HHV-6 reactivation risk while the impact of letermovir for CMV prophylaxis - and resulting decrease in broad-spectrum antivirals - is more complex. Beyond the well established HHV-6 encephalitis, recent evidence implicates HHV-6 in pneumonitis. Novel less toxic therapeutic approaches (brincidofovir, virus-specific T-cells) may enable preventive strategies in the future. HHV-8 is the causal agent of Kaposi's sarcoma, which is only sporadically reported after HCT, but other manifestations are possible and not well elucidated. Parvovirus B19 can cause severe disease post-HCT, frequently manifesting with anemia, but can also be easily overlooked due to lack of routine screening and ambiguity of manifestations.

SUMMARY

Studies should establish the contemporary epidemiology of HHV-6, and other more insidious viruses, such as HHV-8 and parvovirus B19 following HCT and should encompass novel cellular therapies. Standardized and readily available diagnostic methods are key to elucidate epidemiology and optimize preventive and therapeutic strategies to mitigate the burden of infection.

Ensuring Transfusion Safety: Screening Blood Donors for Human Parvovirus B19

Ensuring the safety of blood and blood products is a vital aspect of healthcare. The potential for transmission of pathogens through blood and blood products makes transfusion safety a significant concern. Despite advancements in testing methodologies, donated blood products still pose a risk for infection transmission. Human parvovirus B19 (B19V) is a small, single-stranded, non-enveloped DNA virus transmissible parenterally by blood transfusion. B19V causes a wide range of clinical manifestations, which is generally harmless in healthy individuals. B19V infection may cause severe complications, such as aplastic crises, as it affects erythrocyte progenitor cells in individuals with increased erythrocyte turnover. Additionally, B19V can be transmitted from pregnant women to their foetus, potentially causing hydrops fetalis and foetal death. The potential for transmission through blood and blood products makes B19V a significant concern for transfusion safety. In response to the growing recognition of B19V's impact on transfusion safety, various international health organisations have introduced guidelines to minimise its transmission through blood and plasma products. However, the implementation of these guidelines varies globally, with some regions, such as India, still lacking formal protocols for B19V monitoring. This review article explores the existing methodologies for screening blood donors for B19V, assesses the associated transfusion risks, and considers the implications for public health and clinical practice. By emphasising advancements in diagnostic techniques and the challenges of their implementation, this article provides a comprehensive overview of efforts to reduce the transmission of B19V through blood transfusions, thereby ensuring safer blood supplies and improved patient outcomes.

Parvovirus B19 infection in pediatric allogeneic hematopoietic cell transplantation - Single-center experience and review

BACKGROUND

Parvovirus B19 (B19V) infection following pediatric hematopoietic cell transplantation (HCT) is a rare complication and available data is scarce. Therefore, we present the experience with B19V Infection in allogeneic pediatric HCT recipients at our transplant center together with a systematic review of the literature.

METHODS

Pediatric HCT patients with Parvovirus B19 infection treated at the University Children's Hospital Münster between 1999 and 2021 were retrospectively identified and clinical data were analyzed. Additionally, a systematic MEDLINE search to identify relevant articles was performed.

RESULTS

We identified three out of 445 patients (0.6%) with B19V infection post-transplantation. B19V infection occurred in combination with other complications like Graft-versus-Host disease, additional infections, or autoimmune-mediated hemolysis potentially triggered by B19V. In one patient these complications lead to a fatal outcome. The review of the literature showed considerable morbidity of B19V infection with the potential for life-threatening complications. Most patients were treated by red blood cell transfusion and intravenous immunoglobulins (IVIG) with a high succession rate.

CONCLUSION

Symptomatic B19V infection following HCT remains a rare but potentially challenging complication. A causal antiviral therapy does not exist as well as general recommendations on dosage and duration of IVIG therapy. Despite this, most patients are treated successfully with these measures. Additionally, transmission via blood or stem cell products is also rare and no general recommendations on B19V screenings exist.

A literature review on the parvovirus B19 infection in sickle cell anemia and β-thalassemia patients

BACKGROUND

Parvovirus B19 is the causative agent for erythema infectiosum, and also as a potentially life-threatening infectious agent, it is mainly presented in high erythrocyte turnover patients. Sickle cell disease (SCD) is an inherited monogenic hematological disorder resulting from the mutations in the hemoglobin β-chain gene. Thalassemia is a hereditary hematological syndrome that happens in consequence of deficiencies in the production of one or more globin chains. We summarize current knowledge about the prevalence rates of the parvovirus B19 infection in sickle cell anemia and thalassemia patients.

METHODS

Several online databases were searched including, Scopus, EMBASE, Web of Science, Google Scholar, and PubMed, which were performed amidst 2009-2019 by using distinct keywords: "Thalassemia," "Parvovirus," "Anemia," "Sickle cell anemia," "parvoviridae," "parvoviridae infection," and "parvovirus B19."

RESULTS

Search results indicated 4 and 7 studies for the prevalence of the parvovirus B19 in β-thalassemia and SCD, respectively. Among the β-thalassemia patients, the B19V seroprevalence for IgG and IgM were ranged from 18.2-81% and 14.5-41.1%, respectively; meanwhile, B19V DNA positively results was 4-15.3%. Moreover, in the SCD group, the extent of B19V IgG was varied from 37.6 to 65.9% and that of IgM was in a range of 2.9-30%, and the DNA detection rate was 4-54%.

CONCLUSION

B19V seroprevalence changes in several conditions including, different epidemiological features, socio-economic status, and overpopulation. Age can expand the incidence of anti-B19V IgG/IgM in SCD and beta-thalassemia patients. Reinfection and diverse genotypes are relevant factors in the seroprevalence of B19v. The patients' immunological-hematological station and higher abundance of transfusions can affect the B19V seroprevalence in SCD and beta-thalassemia group. Further investigations in this field could be suggested to better understand the virus distribution in this susceptible population of patients.

Screening for Human Parvovirus B19 Infection in Egyptian Family Replacement Blood Donors

Up till now, screening for human parvovirus B19 is not routine in national Egyptian blood bank strategy. Blood samples were collected from 500 healthy blood donors within the age range from 18 to 45 years old attending the blood bank of Suez Canal University Hospital, Ismailia, Egypt. Sera were separated and stored at - 20 °C. Serum samples were screened for anti-human parvovirus B19 IgM and IgG antibodies and B19 genome using ELISA and real-time PCR respectively. Frequency of B19 IgM and B19 IgG antibodies was 6.20%, and 80.20% respectively, and the prevalence of B19 genome was 3.00%. There is a high frequency of human parvovirus B19 among Egyptian blood donors; therefore, serological screening for B19 is warranted.

Impact of Blood Transfusion on the Prevalence of HHpgV-1, HPgV-1, and B19V Among Iranian HCV-infected Patients With Hemophilia

OBJECTIVE

Blood-derived products from patient with hemophilia treated by factor VIII concentrates are potential sources of transfusion-transmitted infections, including human immunodeficiency virus, hepatitis, human pegivirus-1 (HPgV-1), B19 virus, and also human hepegivirus-1 (HHpgV-1). In the current study, we investigated the impact of blood transfusion on the prevalence of HHpgV-1, HPgV-1, and B19 virus in plasma of Iranian patient with hemophilia after direct-acting antiviral treatment of hepatitis C virus (HCV) infections for the first time.

MATERIALS AND METHODS

A total of 170 patients with hemophilia who received direct-acting antivirals were enrolled in this study. Among them, 92 patients had a history of blood transfusion. The presence of HHpgV-1, HPgV-1, and B19 virus was detected by nested polymerase chain reaction analysis using the conserved primers. The plasmids harboring 5'-UTR and NS3 were used as positive controls for HPgV-1 and HHpgV-1, respectively.

RESULTS

Our data identified 3 individuals with HHpgV-1 viremia (1.76%), 11 individuals with HPgV-1 viremia (6.47%), and 33 individuals with B19 viremia (19.4%). All patients were negative for hepatitis B virus, human immunodeficiency virus, and HCV infections. These findings indicated lower transmissibility or higher rates of virus clearance for HHpgV-1, HPgV-1, and B19 virus as compared with other bloodborne human flaviviruses such as HCV. However, the prevalence of B19 virus was significantly higher than the other 2 viruses.

CONCLUSION

In general, these findings showed that the history of blood transfusion could increase the risk of viral transmission of bloodborne viruses among patient with hemophilia.

First Report of Prevalence of Blood-Borne Viruses (HBV, HCV, HIV, HTLV-1 and Parvovirus B19) Among Hemophilia Patients in Afghanistan

Blood-borne viruses including Hepatitis B and C, HIV, HTLV-1 and parvovirus B19 are still a factor of concern, especially for hemophilia patients. Although the safety of the blood supply continues to improve worldwide, the blood supply system in Afghanistan was damaged by many years of conflict and political instability. To date, there are few studies focused on the prevalence of blood-borne viruses in hemophilia patients. This study is first to investigate the prevalence of five blood-borne viruses in Afghanistan hemophilia patients in four cities including Kabul, Herat, Mazar-i-Sharif and Jalal Abad. A total of 80 hemophilia male patients were screening for the presence of five transfusion-transmitted viruses using ELISA and PCR. Data obtained showed 2.5% seropositivity for HBV, 8.75% seropositivity for HCV, and 91.25% seropositivity for parvovirus B19. None of the patients were positive for HIV and HTLV-1 and the prevalence of HCV was higher in older patients rather than younger patients. This finding, the first to report in Afghanistan, shows a high prevalence of parvovirus B19 in Afghanistan hemophilia patients and implementation of highly sensitive screening is 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.

Infections with DNA Viruses, Adenovirus, Polyomaviruses, and Parvovirus B19 in Hematopoietic Stem Cell Transplant Recipients and Patients with Hematologic Malignancies

Infections due to adenovirus, polyomaviruses (BK and JC viruses), and parvovirus B19 may not be as common as infections due to other DNA viruses, such as cytomegalovirus in patients with hematological malignancies and the recipients of hematopoietic stem cell transplantation. However, these infections may result in life-threatening diseases that significantly impact patients' recovery, morbidity, and mortality. Treating physicians should be aware of the diseases associated with these viruses, the patient populations at increased risk for complications due to these infections, and the available diagnostic and therapeutic approaches.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Parvovirus B19

Primary parvovirus B19 infection is an infrequent, but serious and treatable, cause of chronic anemia in immunocompromised hosts. Many compromised hosts have preexisting antibody to B19 and are not at risk. However, upon primary infection, some patients may be able to mount a sufficient immune response to terminate active parvovirus B19 infection of erythroid precursors. The most common consequence of B19 infection in the compromised host is pure red-cell aplasia, resulting in chronic or recurrent anemia with reticulocytopenia. Anemia persists until neutralizing antibody is either produced by the host or passively administered. Parvovirus B19 should be suspected in compromised hosts with unexplained or severe anemia and reticulocytopenia, or when bone-marrow examination shows either giant pronormoblasts or absence of red-cell precursors. Diagnosis is established by detection of B19 DNA in serum in the absence of IgG antibody to B19. In some cases, IgG antibody is detected but is not neutralizing. Anti-B19 IgM may or may not be present. Therapy includes any or all of the following: red-cell transfusion, adjustment in medications to restore or improve the patient’s immune system, and administration of intravenous immunoglobulin (IVIG). Following treatment, patients should be closely monitored, especially if immunosuppression is unchanged or increased. Should hematocrit trend downward and parvovirus DNA trend upward, the therapeutic options above should be revisited. In a few instances, monthly maintenance IVIG may be indicated. Caregivers should be aware that B19 variants, though rarely encountered, can be missed or under-quantitated by some real-time polymerase-chain reaction methods.

Safety of the blood supply

BACKGROUND

The transfusion of blood components plays a significant role as supportive therapy in the treatment of patients with cancer. Although blood transfusions help manage complications arising from either the patient's primary condition or associated with therapeutic intervention, their use introduces a new set of risks; therefore, health care professionals must be aware of the potential morbidity introduced by using blood components and endeavor to optimize outcomes by ordering transfusions only when the benefits outweigh the inherent risks.

METHODS

This article sought to review the published literature, including the epidemiology of diseases transmissible via transfusion, performance characteristics for assays used for blood donor screening, surveillance activities to detect newly emergent pathogens, and biovigilance activities reported by public health authorities.

RESULTS

Effective measures have been implemented to significantly decrease the risk of transmissible diseases associated with transfusion. Reports of viral disease transmitted via transfusion have been nearly eliminated, particularly since the introduction of molecular-based detection technology. The transmission of bacteria and parasites still represents a threat to the use of cellular blood components. Transfusion-associated human prion disease has not been reported in the United States. Immune-mediated reactions due to donor-recipient incompatibility remain a challenge.

CONCLUSIONS

Transmissible agents most commonly associated with risks due to transfusion are no longer a major threat; however, a significant challenge remains with regard to addressing the need for quick response mechanisms to manage emerging pathogens with the potential for rapid spread, either unintentionally (eg, globalization) or intentionally (eg, bioterrorism). The use of technology to reduce pathogens holds promise for further increasing the safety profile of blood transfusion.

Investigation of epstein-barr virus and parvovirus b19 DNA in allogeneic stem cell transplant patients

OBJECTIVE

We aimed to investigate posttransplant Epstein-Barr virus (EBV) and parvovirus B19 DNA in allogeneic stem cell transplant patients between 2009 and 2010.

MATERIALS AND METHODS

Forty-five adult patients in whom allogeneic stem cell transplantation was performed between April 2009 and November 2010 in the Erciyes University Faculty of Medicine, Department of Internal Medicine, Division of Hematology and Oncology, were included in the study. EBV and parvovirus B19 DNA positivity was investigated by using real-time polymerase chain reaction technique in 135 plasma samples obtained after transplantation at between 1 and 6 months. Pretransplant serological markers of EBV and parvovirus B19 were provided from patient files.

RESULTS

In 32 (71.1%) of the patients, EBV antibodies in the pretransplantation period were as follows: anti-EBNA-1 IgG (+), VCA IgM (-), and VCA IgG (+). In 2 patients (4.45%), these antibodies were as follows: anti-EBNA-1 IgG (+), VCA IgM (-), and VCA IgG (-). In 1 patient (2.2%), they were as follows: anti-EBNA-1 IgG (-), VCA IgM (-), and VCA IgG (+). EBV serological markers were negative in 2 (2.2%) out of 45 patients before transplantation. There was low DNA positivity (<600 copies/mL) in 4 patients (8.9%), and VCA IgM was negative and VCA IgG was positive in these same 4 patients. In spite of low viral load, there were no symptoms related to EBV, and posttransplant lymphoproliferative disorder (PTLD) did not occur. While in 44 (99.7%) of 45 patients parvovirus B19 IgM was negative and IgG was positive, parvovirus B19 IgM was positive and IgG was negative in 1 (2.3%) patient. Parvovirus B19 DNA was not identified in any of the samples obtained from these 45 patients.

CONCLUSION

In this study, EBV and parvovirus B19 DNA were investigated in allogeneic stem cell transplant patients. None of the patients developed PTLD and parvovirus B19 DNA positivity was not detected. However, this issue needs to be further evaluated in prospective, multicenter studies with larger series of patients.

Seroprevalence of human parvovirus B19 in healthy blood donors

BACKGROUND

Human parvovirus B19 is an emerging transfusion transmitted infection. Although parvovirus B19 infection is connected with severe complications in some recipients, donor screening is not yet mandatory. To reduce the risk of contamination, plasma-pool screening and exclusion of highly viraemic donations are recommended. In this study the prevalence of parvovirus B19 in healthy blood donors was detected by ELISA.

METHODS

A total of 1633 samples were screened for IgM and IgG antibodies against parvovirus B19 by ELISA. The initial 540 samples were screened for both IgM and IgG class antibodies and remaining 1093 samples were screened for only IgM class antibodies by ELISA.

RESULTS

Net prevalence of IgM antibodies to human parvovirus B19 in our study was 7.53% and prevalence of IgG antibodies was 27.96%. Dual positivity (IgG and IgM) was 2.40%.

CONCLUSION

The seroprevalence of human parvovirus B19 among blood donor population in our study is high, and poses an adverse transfusion risk especially in high-risk group of patients who have no detectable antibodies to B19. Studies with large sample size are needed to validate these results.

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.

Parvovirus B19 infection transmitted by transfusion of red blood cells confirmed by molecular analysis of linked donor and recipient samples

BACKGROUND

Extremely high viremic levels of parvovirus B19 (B19V) can be found in acutely infected, but asymptomatic donors. However, reports of transmission by single-donor blood components are rare. In this prospective study, paired donor-recipient samples were used to investigate the transfusion risk.

STUDY DESIGN AND METHODS

Posttransfusion plasma or blood samples from recipients were tested for B19V DNA by polymerase chain reaction, generally at 4 and 8 weeks, and for anti-B19V immunoglobulin (Ig)G by enzyme immunoassay, at 12 and 24 weeks. To rule out infection unrelated to transfusion, pretransfusion samples and linked donor's samples for each B19V DNA-positive recipient were assayed for B19V DNA and anti-B19V IgG and IgM. To confirm transmission, sequencing and phylogenetic analysis were performed.

RESULTS

A total of 14 of 869 (1.6%) recipients were B19V DNA positive, but only 1 of 869 (0.12%; 95% confidence interval, 0.0029%-0.6409%) was negative for B19V DNA and anti-B19V IgG before transfusion and seroconverted posttransfusion. This newly infected patient received 5 × 10(10) IU B19V DNA in one red blood cell (RBC) unit from an acutely infected anti-B19V-negative donor in addition to RBCs from three other donors that cumulatively contained 1320 IU of anti-B19V IgG. DNA sequencing and phylogenetic analysis showed that sequences from the linked donor and recipient were identical (Genotype 1), thus establishing transfusion transmission.

CONCLUSIONS

The 0.12% transmission rate documented here, although low, could nonetheless result in hundreds or thousands of infections annually in the United States based on calculated confidence limits. Although most would be asymptomatic, some could have severe clinical outcomes, especially in neonates and those with immunocompromised or hemolytic states.

A linked donor-recipient study to evaluate parvovirus B19 transmission by blood component transfusion

Parvovirus B19V infection can be a serious infection for hematology patients with underlying hemolysis or compromised erythropoiesis syndromes. Although case reports of B19V transmission by blood component transfusion (as contrasted to manufactured plasma derivatives) are rare, no studies have systematically determined a rate of transmission to recipients transfused with B19V DNA-positive components. We used a linked donor and recipient repository and a sensitive, quantitative B19V DNA polymerase chain reaction (PCR) assay to assess such transmission in B19V-susceptible (ie, anti-B19V immunoglobulin G [IgG] negative) recipients. We assessed 112 B19V DNA-positive components from 105 donors (of 12 529 tested donations) transfused into a population of surgical patients with a pretransfusion B19V IgG seroprevalence of 78%. We found no transmission to 24 susceptible recipients from transfusion of components with B19V DNA at concentrations less than 10(6) IU/mL (upper 95% confidence interval, 11.7%). We found an anamnestic IgG response in one pretransfusion seropositive recipient transfused with a component containing greater than 10(10) IU/mL B19V DNA. These findings show either that transmission from components with less than 10(6) IU/mL does not occur, or, if it does, it is an uncommon event. These data do not support the need to routinely screen blood donations with a sensitive B19V DNA nucleic acid assay.

Persistence of human parvovirus B19 in multipotent mesenchymal stromal cells expressing the erythrocyte P antigen: implications for transplantation

Multipotent mesenchymal stromal cells (MSCs) are used to improve the outcome of hematopoietic stem cell transplantation (HCST) and in regenerative medicine. MSCs may harbor persistent viruses that may compromise their clinical benefit, however. Retrospectively screened, 1 of 20 MSCs from healthy donors contained parvovirus B19 (B19) DNA. MSCs express the B19 receptor (P antigen/globoside) and a co-receptor (Ku 80) and can transmit B19 to bone marrow cells in vitro, suggesting that the virus can persist in the marrow stroma of healthy individuals. Two patients undergoing HSCT received the B19-positive MSCs as treatment for graft-versus-host disease; neither developed viremia nor symptomatic B19 infection. These findings demonstrate for the first time that persistent B19 in MSCs can infect hematopoietic stem cells and underscore the importance of monitoring B19 transmission by MSC products.

Simultaneous persistence of multiple genome variants of human parvovirus B19

The species human parvovirus B19 (B19V) can be divided into three genotypes. In this study, we addressed the question as to whether infection of an individual is restricted to one genotype. As viral DNA is detectable in tissue for long times after acute infection, we examined 87 liver specimens from adults for the presence of B19V DNA. Fifty-nine samples were found to be positive, 32 of them for genotype 1, 27 for genotype 2 and four for genotype 3. In four samples, DNA of two genotypes was detected; samples from three individuals were positive for genotypes 1 and 2 and a sample from one individual was positive for genotypes 1 and 3. Surprisingly, significant sequence heterogeneity was observed at approximately 1 % of the nucleotides of the genotype 1 genomes from individuals with double genotype 1 and 2 infection. Controls using different enzymes for genome amplification and dilutions of the template verified that nucleotide heterogeneity was due to the presence of three or more genome variants of genotype 1. In summary, the evidence shows that individuals can be infected with two different genotypes, and B19V DNA can persist as a population of different genomes. The results may have implications for the understanding of the antiviral immune response and the development of vaccines against B19V.

Molecular mechanism underlying B19 virus inactivation and comparison to other parvoviruses

BACKGROUND

B19 virus (B19V) is a human pathogen frequently present in blood specimens. Transmission of the virus occurs mainly via the respiratory route, but it has also been shown to occur through the administration of contaminated plasma-derived products. Parvoviridae are highly resistant to physicochemical treatments; however, B19V is more vulnerable than the rest of parvoviruses. The molecular mechanism governing the inactivation of B19V and the reason for its higher vulnerability remain unknown.

STUDY DESIGN AND METHODS

After inactivation of B19V by wet heat and low pH, the integrity of the viral capsid was examined by immunoprecipitation with two monoclonal antibodies directed to the N-terminal of VP1 and to a conformational epitope in VP2. The accessibility of the viral DNA was quantitatively analyzed by a hybridization-extension assay and by nuclease treatment.

RESULTS

The integrity of the viral particles was maintained during the inactivation procedure; however, the capsids became totally depleted of viral DNA. The DNA-depleted capsids, although not infectious, were able to attach to target cells. Comparison studies with other members of the Parvoviridae family revealed a remarkable instability of B19V DNA in its encapsidated state.

CONCLUSION

Inactivation of B19V by heat or low pH is not mediated by capsid disintegration but by the conversion of the infectious virions into DNA-depleted capsids. The high instability of the viral DNA in its encapsidated state is an exclusive feature of B19V, which explains its lower resistance to inactivation treatments.

Prevalence and quantitation of parvovirus B19 DNA levels in blood donors with a sensitive polymerase chain reaction screening assay

BACKGROUND

Blood donor parvovirus B19 DNA prevalence with sensitive nucleic acid test assays has recently been demonstrated to be higher than that found with assays designed to detect high viral titers in the plasma manufacturing sector.

STUDY DESIGN AND METHODS

Stored plasma aliquots from 5020 donations collected between 2000 and 2003 at seven US blood centers were tested. Testing was performed with a real-time B19 DNA polymerase chain reaction (PCR; TaqMan, Applied Biosystems) assay with a 50 percent limit of detection (LOD) of 1.6 IU per mL (95% confidence interval [CI], 1.2-2.1 IU/mL) and a 95 percent LOD of 16.5 IU per mL (95% CI, 10.6-33.9 IU/mL). Confirmation and quantitation of B19 DNA was accomplished by retesting of two additional subaliquots. Confirmed-positive specimens were tested for the presence of anti-B19 immunoglobulin M (IgM) and IgG with FDA-licensed assays.

RESULTS

B19 DNA prevalence was 0.88 percent (95% CI, 0.64%-1.2%). Among the 23 donations with B19 DNA titers of at least 20 IU per mL, the median DNA concentration was 105 IU per mL with an interquartile range of 42 to 481 IU per mL; the highest value was 1869 IU per mL. All B19 DNA-positive donations were positive for the presence of IgG and 10 (23%) were also positive for the presence of IgM; IgM seropositivity was associated with increasing DNA levels (p = 0.0013).

CONCLUSION

Low-level B19 DNA was detected in nearly 1 percent of donations. The 23 percent of DNA-positive donations with both IgM and IgG B19 antibody most likely represent acute resolving infection, whereas those with IgG but no IgM are most consistent with a more chronic and possibly persistent phase of B19 infection.

Parvovirus B19 DNA in Factor VIII concentrates: effects of manufacturing procedures and B19 screening by nucleic acid testing

BACKGROUND

Parvovirus B19 (B19) is a common contaminant, especially in coagulation factors. Because of B19 transmission by pooled plasma, solvent/detergent treated in 1999, some fractionators initiated minipool nucleic acid testing (NAT) to limit the B19 load in manufacturing pools. In this study, the extent of B19 DNA contamination in commercial Factor VIII concentrates, that is, antihemophilic factor (human) (AHF), manufactured before and after B19 NAT screening was implemented, was determined.

STUDY DESIGN AND METHODS

A total of 284 lots representing six AHF products made during 1993 to 1998 and 2001 to 2004 were assayed for B19 DNA by an in-house NAT procedure. Anti-B19 immunoglobulin G (IgG) was also measured.

RESULTS

Most lots made during 1993 to 1998 had detectable B19 DNA. The prevalence ranged from 56 to 100 percent and appeared to differ between manufacturers. The highest level of B19 DNA found was 10(6) genome equivalents (geq or international units [IU]) per mL. Forty percent of the lots tested contained 10(3) geq (IU) per mL. In comparison, both prevalence and levels in source plasma-derived AHF products made in 2001 to 2004 were lower. Both, however, remained unchanged in the recovered plasma-derived product because B19 NAT screening had not been implemented. Only an intermediate-purity AHF product was positive for the presence of anti-B19 IgG.

CONCLUSION

The prevalence and levels of B19 DNA in AHF prepared from B19 NAT unscreened plasma were high but varied among products with different manufacturing procedures. B19 NAT screening of plasma effectively lowered the B19 DNA level in the final products and in the majority of cases rendered it undetectable and hence potentially reduced the risk of B19 transmission.

Transfusion-transmitted infections

Although the risk of transfusion-transmitted infections today is lower than ever, the supply of safe blood products remains subject to contamination with known and yet to be identified human pathogens. Only continuous improvement and implementation of donor selection, sensitive screening tests and effective inactivation procedures can ensure the elimination, or at least reduction, of the risk of acquiring transfusion transmitted infections. In addition, ongoing education and up-to-date information regarding infectious agents that are potentially transmitted via blood components is necessary to promote the reporting of adverse events, an important component of transfusion transmitted disease surveillance. Thus, the collaboration of all parties involved in transfusion medicine, including national haemovigilance systems, is crucial for protecting a secure blood product supply from known and emerging blood-borne pathogens.

Quantification of viral inactivation by photochemical treatment with amotosalen and UV A light, using a novel polymerase chain reaction inhibition method with preamplification

Background. In evaluating a photochemical treatment process for inactivating parvovirus B19, there lacked simple culture methods to measure infectivity. The recently developed enzyme‐linked immunospot (ELISpot) infectivity assay uses late‐stage erythropoietic progenitor cells and is labor intensive and time consuming. We evaluated a novel, efficient polymerase chain reaction (PCR) inhibition assay and examined correlations with reductions in infectivity.

Methods. Contaminated plasma was treated with 150 μmol/L amotosalen and 3 J/cm² ultraviolet A light and then tested for DNA modification using conventional PCR inhibition and a novel preamplification approach. The novel assay subjected the samples to preamplification cycles using long‐template PCR, followed by quantitative PCR (QPCR) inhibition detection. Both approaches were tested for correlations with reductions in viral infectivity by comparing ELISpot assay results of identical samples.

Results. The B19 preamplification inhibition assay showed detection ranges of 2–2.5 log and demonstrated quantitative correlation with up to a 5.8‐log reduction in viral infectivity in ELISpot results. Conventional PCR detected a >5 log reduction in amplification, correlated with a 4.4‐log reduction in viral infectivity. A range of 4‐log inhibition of hepatitis B virus DNA amplification was also achieved.

Conclusions. The results demonstrated that a novel preamplification QPCR assay is a useful tool for predicting reductions in infectivity after photochemical treatment. This assay was extended to show utility in circumstances where practical in vitro assays are unavailable for the determination of the efficacy of pathogen inactivation.

Clinical aspects of parvovirus B19 infection

Parvovirus B19 is a significant human pathogen that causes a wide spectrum of clinical complications ranging from mild, self-limiting erythema infectiosum in immunocompetent children to lethal cytopenias in immunocompromised patients and intrauterine foetal death in primary infected pregnant women. The infection may also be persistent and can mimic or trigger autoimmune inflammatory disorders. Another important clinical aspect to consider is the risk of infection through B19-contaminated blood products. Recent advances in diagnosis and pathogenesis, new insights in the cellular immune response and newly discovered genotypes of human parvoviruses form a platform for the development of modern therapeutic and prophylactic alternatives.

[Safety of blood products and B19 parvovirus]

More than 25 years after the discovery of the parvovirus B19 (B19), the issue of the safety of blood components and the screening of this virus in blood donations is still debated. Although more often transmitted by respiratory route, B19 may also be transmitted by transfusion of blood components. This risk of exposure has been estimated to a frequency ranging from 1/625 to 1/50,000, according to the sensitivity of the detection methods and to seasonal epidemiologic circumstances. Usually, B19 is responsible for benign pathologies. However, such an infection can have a serious clinical outcome in three categories of susceptible recipients: (i) patients with shortened red cell survival (thalassemia major, sickle cell disease, other hemolytic diseases); (ii) immunocompromised patients (previously exposed to B19 or not) (iii) and pregnant women (not previously exposed the B19), with a risk of hydrops fetalis or of intrauterine death. Selected blood components, not collected during the short but highly viremic pre-seroconversion phase, could be reserved for these three groups of at-risk recipients. The screening of such viremic donations could be performed with nucleic acid testing (NAT), but an alternate strategy could be the selection of B19 immunised donors far from the primo-infection (positive for B19 IgG and negative for B19 IgM, or only positive for IgG at two controls distant of several months). However, the existence of persistently B19-infected individuals carrying B19 DNA despite the presence of specific IgG (estimated at 1% of blood donors) could constitute a potential threat for transfused immunocompromised recipients. The screening of such donors, which could be performed through a very highly sensitive NAT, would be justified only if the infectivity of such blood donations is demonstrated. If not, a screening of blood donors positive for B19 IgG would be a sufficient preventive measure.