Kinetics of inactivating human parvovirus B19 and porcine parvovirus by dry-heat treatment

Transfusion-Transmitted Disorders 2023 with Special Attention to Bone Marrow Transplant Patients

Transfusion medicine is traditionally a strong/fundamental part of clinical practice, saving hundreds of millions of lives. However, blood-borne or transmitted infections are a well-known and feared possibility, a risk we relentlessly mitigate. Pathogens are continuously and rather quickly changing, so during the last decade, many, sometimes exotic, new pathogens and diseases were recorded and analyzed, and some of them were proved to be transmitted with transfusions. Blood or blood component transfusions are carried out after cautious preparative screening and inactivation maneuvers, but in some instances, newly recognized agents might escape from standard screening and inactivation procedures. Here, we try to focus on some of these proven or potentially pathogenic transfusion-transmitted agents, especially in immunocompromised patients or bone marrow transplantation settings. These pathogens are sometimes new challenges for preparative procedures, and there is a need for more recent, occasionally advanced, screening and inactivation methods to recognize and eliminate the threat a new or well-known pathogen can pose. Pathogen transmission is probably even more critical in hemophiliacs or bone marrow transplant recipients, who receive plasma-derived factor preparations or blood component transfusions regularly and in large quantities, sometimes in severely immunosuppressed conditions. Moreover, it may not be emphasized enough that transfusions and plasma-derived product administrations are essential to medical care. Therefore, blood-borne transmission needs continued alertness and efforts to attain optimal benefits with minimized hazards.

New Parvovirus Associated with Serum Hepatitis in Horses after Inoculation of Common Biological Product

Equine serum hepatitis (i.e., Theiler's disease) is a serious and often life-threatening disease of unknown etiology that affects horses. A horse in Nebraska, USA, with serum hepatitis died 65 days after treatment with equine-origin tetanus antitoxin. We identified an unknown parvovirus in serum and liver of the dead horse and in the administered antitoxin. The equine parvovirus-hepatitis (EqPV-H) shares <50% protein identity with its phylogenetic relatives of the genus Copiparvovirus. Next, we experimentally infected 2 horses using a tetanus antitoxin contaminated with EqPV-H. Viremia developed, the horses seroconverted, and acute hepatitis developed that was confirmed by clinical, biochemical, and histopathologic testing. We also determined that EqPV-H is an endemic infection because, in a cohort of 100 clinically normal adult horses, 13 were viremic and 15 were seropositive. We identified a new virus associated with equine serum hepatitis and confirmed its pathogenicity and transmissibility through contaminated biological products.

Viral testing of 18 consecutive cases of equine serum hepatitis: A prospective study (2014-2018)

Background

Three flaviviruses (equine pegivirus [EPgV]; Theiler's disease–associated virus [TDAV]; non‐primate hepacivirus [NPHV]) and equine parvovirus (EqPV‐H) are present in equine blood products; the TDAV, NPHV, and EqPV‐H have been suggested as potential causes of serum hepatitis.

Objective

To determine the prevalence of these viruses in horses with equine serum hepatitis.

Animals

Eighteen horses diagnosed with serum hepatitis, enrolled from US referral hospitals.

Methods

In the prospective case study, liver, serum, or both samples were tested for EPgV, TDAV, NPHV, and EqPV‐H by PCR.

Results

Both liver tissue and serum were tested for 6 cases, serum only for 8 cases, and liver only for 4 cases. Twelve horses received tetanus antitoxin (TAT) 4‐12.7 weeks (median = 8 weeks), 3 horses received commercial equine plasma 6‐8.6 weeks, and 3 horses received allogenic stem cells 6.4‐7.6 weeks before the onset of hepatic failure. All samples were TDAV negative. Two of 14 serum samples were NPHV‐positive. Six of 14 serum samples were EPgV‐positive. All liver samples were NPHV‐negative and EPgV‐negative. EqPV‐H was detected in the serum (N = 8), liver (N = 4), or both samples (N = 6) of all 18 cases. The TAT of the same lot number was available for virologic testing in 10 of 12 TAT‐associated cases, and all 10 samples were EqPV‐H positive.

Conclusions and Clinical Importance

We demonstrated EqPV‐H in 18 consecutive cases of serum hepatitis. EPgV, TDAV, and NPHV were not consistently present. This information should encourage blood product manufacturers to test for EqPV‐H and eliminate EqPV‐H–infected horses from their donor herds.

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.

Efficacy and safety of Wilate in paediatric VWD patients under 6 years of age - results of a prospective multicentre clinical study including recovery information

Treatment with exogenous von Willebrand factor (VWF) is indicated in patients with von Willebrand disease (VWD) in whom treatment with 1-deamino-8-d-arginine vasopressin/desmopressin is contraindicated. Wilate is a new generation plasma-derived concentrate of native VWF and coagulation factor VIII (FVIII) (in a physiological 1:1 ratio) developed for the treatment of VWD. This is the first study to report safety, efficacy and in vivo recovery (IVR) data from 15 paediatric patients less than 6 years of age who received Wilate for either prophylaxis, on-demand treatment or for treatment in surgical procedures during a prospective open-label trial (VWD type 1: 5, type 2A: 1, type 2B: 2, type 3: 6, unknown type: 1 patients). Analysis of IVR for VWF and FVIII suggested an appropriate and consistent rise in coagulation activity after Wilate administration. Overall efficacy was rated as excellent or good for 99.7% [prophylactic infusions] and 100% [bleeding episodes/surgical procedures]. More than 82% of bleeding episodes resolved after 1 day of treatment, and a Wilate dosage of 20-50 IU kg(-1) was sufficient to achieve haemostasis in 97% of bleeding episodes. All surgical procedures were successfully managed with Wilate. No thromboembolic events were observed during the study, and no patient developed anti-VWF antibodies or FVIII inhibitors. In conclusion, this study confirms both the expected IVR profile in paediatric patients and the excellent efficacy, tolerability and safety profile of Wilate observed previously in adults. Wilate showed excellent efficacy in the treatment of bleeding when used prophylactically or on-demand, and in the treatment of surgical procedures.

The first recombinant human coagulation factor VIII of human origin: human cell line and manufacturing characteristics

INTRODUCTION

Since the early 1990s, recombinant human clotting factor VIII (rhFVIII) produced in hamster cells has been available for haemophilia A treatment. However, the post-translational modifications of these proteins are not identical to those of native human FVIII, which may lead to immunogenic reactions and the development of inhibitors against rhFVIII. For the first time, rhFVIII produced in a human host cell line is available.

AIM

We describe here the establishment of the first human production cell line for rhFVIII and the manufacturing process of this novel product.

METHODS AND RESULTS

A human cell line expressing rhFVIII was derived from human embryonic kidney (HEK) 293 F cells transfected with an FVIII expression plasmid. No virus or virus-like particles could be detected following extensive testing. The stringently controlled production process is completely free from added materials of animal or human origin. Multistep purification employing a combination of filtration and chromatography steps ensures the efficient removal of impurities. Solvent/detergent treatment and a 20 nm pore size nanofiltration step, used for the first time in rhFVIII manufacturing, efficiently eliminate any hypothetically present viruses. In contrast to hamster cell-derived products, this rhFVIII product does not contain hamster-like epitopes, which might be expected to be immunogenic.

CONCLUSIONS

HEK 293 F cells, whose parental cell line HEK 293 has been used by researchers for decades, are a suitable production cell line for rhFVIII and will help avoid immunogenic epitopes. A modern manufacturing process has been developed to ensure the highest level of purity and pathogen safety.

Inactivation and neutralization of parvovirus B19 Genotype 3

BACKGROUND

Parvovirus B19 (B19V) is a common contaminant of human plasma donations. Three B19V genotypes have been defined based on their DNA sequence. Reliable detection of Genotype 3 DNA has proved problematic because of unexpected sequence variability. B19V Genotype 3 is found primarily in West Africa, but was recently detected in plasma from a North American donor. The safety of plasma-derived medicinal products, with respect to B19V, relies on exclusion of high-titer donations, combined with virus clearance at specific manufacturing steps. Studies on inactivation of B19V are difficult to perform and inactivation of Genotype 3 has not yet been investigated.

STUDY DESIGN AND METHODS

Inactivation of B19V Genotypes 3 and 1 by pasteurization of human serum albumin and incubation at low pH was studied using a cell culture assay for infectious virus particles. Infected cells were detected by reverse transcription-polymerase chain reaction analysis of virus capsid mRNA. Neutralization of B19V Genotype 3 was investigated using human immunoglobulin preparations.

RESULTS

Genotypes 1 and 3 displayed comparable inactivation kinetics during pasteurization of albumin at 56°C, as well as by incubation at various low-pH conditions (pH 4.2 at 37°C and pH 4.5 at 23°C, respectively) used in immunoglobulin manufacturing. Both Genotypes were readily neutralized by pooled immunoglobulin preparations of North American or European origin.

CONCLUSION

Pasteurization and low-pH treatment were equally effective in inactivating B19V Genotypes 1 and 3. Neutralization experiments indicated that pooled immunoglobulin of North American or European origin is likely to be equally effective in treatment of disease induced by both genotypes.

Effectiveness of nanofiltration in removing small non-enveloped viruses from three different plasma-derived products

The objective of this study was to assess the ability of nanofiltration of albumin solution, prothrombin complex (PTC) and factor IX (FIX) to remove two small, non-enveloped DNA viruses, parvovirus B19 (B19V) and torque teno virus (TTV). Virus removal was investigated with down-scale experiments performed with sequential steps of 35-nm and 15-nm nanofiltrations of products spiked with virus DNA-positive sera. Viral loads were determined by real-time PCRs. The 15-nm nanofiltration removed more than 4.0 B19V log from all the products, TTV was reduced of more than 3.0 log from albumin solution and FIX by 35-nm and 15-nm nanofiltrations, respectively, being viral DNA undetectable after these treatments. Traces of TTV were still found in PTC after the 15-nm nanofiltration. In conclusion, nanofiltration can be efficacious in removing small naked viruses but, since viruses with similar features can differently respond to the treatment, a careful monitoring of large-scale nanofiltration should be performed.