Trypanosoma cruzi inactivation in human platelet concentrates and plasma by a psoralen (amotosalen HCl) and long-wavelength UV

Polymerase chain reaction inhibition assay documenting the amotosalen-based photochemical pathogen inactivation process of platelet concentrates

BACKGROUND

The INTERCEPT Blood System (Baxter Healthcare Corp.) for platelets (PLTs) uses amotosalen-HCl (S-59) in conjunction with ultraviolet A (UVA) light to inactivate contaminating pathogens by modifying the nucleic acids of pathogens. The success of this photochemical treatment (PCT) process can be documented indirectly with a high-performance liquid chromatography assay measuring the photodegradation of amotosalen and measurement of the UVA light dose delivered by the illumination system.

STUDY DESIGN AND METHODS

To develop an assay that documents the success of PCT directly on the effector molecule DNA, the effect of PCT on PLT-derived mitochondrial DNA (mtDNA) was examined. mtDNA-specific polymerase chain reaction (PCR) assays were tested with regard to their susceptibility for PCT, their reliability in terms of PCR performance, and the absence of polymorphic sites in primer hybridization loci.

RESULTS

Suitable PCR amplification targets were found in the regions of 16S rDNA, cytochrome c oxidase I, and cytochrome c oxidase III of mitochondria. Amplicon sizes between 868 and 1248 bp gave consistent signals before PCT and complete inhibition of the PCR signal after PCT. Amplicons of less than 300 bp were found to be transparent to PCT.

CONCLUSION

Based on PCT-mediated mtDNA modifications in PLTs, a PCR inhibition assay was established with a large amplicon documenting the success of PCT and a small amplicon serving as an internal control.

Leishmania inactivation in human pheresis platelets by a psoralen (amotosalen HCl) and long-wavelength ultraviolet irradiation

BACKGROUND

Leishmania spp. are protozoans that cause skin and visceral diseases. Leishmania are obligate intracellular parasites of mononuclear phagocytes and have been documented to be transmitted by blood transfusion.

STUDY DESIGN AND METHODS

This study examines whether Leishmania can be inactivated in human platelet (PLT) concentrates by a photochemical treatment process that is applicable to blood bank use. Human PLT concentrates were contaminated with Leishmania mexicana metacyclic promastigotes or mouse-derived Leishmania major amastigotes and were exposed to long-wavelength ultraviolet (UV) A light (320-400 nm) plus the psoralen amotosalen HCl.

RESULTS

Neither treatment with amotosalen nor UVA alone had an effect on Leishmania viability; however, treatment with 150 micromol per L amotosalen plus 3 J per cm(2) UVA inactivated both metacyclic promastigotes and amastigotes to undetectable levels, more than a 10,000-fold reduction in viability.

CONCLUSIONS

This study demonstrates the effectiveness of photochemical treatment to inactivate Leishmania in PLT concentrates intended for transfusion. Both metacylic promastigotes, which represent the infectious form from the sand fly vector, and amastigotes, which represent the form that grows in mononuclear phagocytes, were extremely susceptible to photochemical inactivation by this process. Thus, the photochemical treatment of PLT concentrates inactivates both forms of Leishmania that would be expected to circulate in blood products collected from infected donors.

In vitro photochemical inactivation of cell-associated human T-cell leukemia virus Type I and II in human platelet concentrates and plasma by use of amotosalen

BACKGROUND

Human T-cell leukemia virus Types I and II (HTLV-I and HTLV-II), blood-borne retroviruses found worldwide, can cause leukemia, immunosuppression, and severe neurologic diseases. In most countries, HTLV-I and -II screening is not performed systematically for blood donations. A new photochemical treatment (PCT) with a synthetic psoralen was developed to inactivate most pathogens in platelet (PLT) concentrates or plasma and to improve the safety of blood donations.

STUDY DESIGN AND METHODS

Cell-associated HTLV-I or -II (10(6)/mL) was inoculated in full-size fresh PLT concentrates or fresh frozen plasma and treated with 150 micromol per L amotosalen (S-59) and different doses of long-wavelength ultraviolet A (UVA) light. The residual viral titer in the treated samples was assessed by a cocultivation assay on indicator cells.

RESULTS

The inactivation obtained at a 3.0 J per cm2 UVA dose was greater than 5.2 log foci-forming units (FFUs) per mL for HTLV-I and 4.6 log FFUs per mL for HTLV-II in presence of human PLT concentrates and greater than 4.5 log FFUs per mL for HTLV-I and 5.7 log FFUs per mL for HTLV-II in the presence of human plasma. The residual infectivity was very low and shown as the limit of detection of the cocultivation assay.

CONCLUSION

In human plasma or PLT concentrates, the retroviruses HTLV-I and -II were strongly sensitive to the PCT with 150 micromol per L amotosalen (S-59) and a 3.0 J per cm2 UVA dose. This high efficiency for photoinactivation of these retroviruses opens a possibility of improving the safety of PLTs or plasma transfusion in the future.

Amotosalen photochemical inactivation of severe acute respiratory syndrome coronavirus in human platelet concentrates

A novel human coronavirus causing severe acute respiratory syndrome (SARS) emerged in epidemic form in early 2003 in China and spread worldwide in a few months. Every newly emerging human pathogen is of concern for the safety of the blood supply during and after an epidemic crisis. For this purpose, we have evaluated the inactivation of SARS-coronavirus (CoV) in platelet concentrates using an approved pathogen inactivation device, the INTERCEPT Blood System. Apheresis platelet concentrates (APCs) were inoculated with approximately 10(6) pfu mL(-1) of either Urbani or HSR1 isolates of SARS-CoV. The inoculated units were mixed with 150 microm amotosalen and illuminated with 3 J cm(-2) UV-A light. The viral titres were determined by plaque formation in Vero E6 cells. Mixing SARS-CoV with APC in the absence of any treatment decreased viral infectivity by approximately 0.5-1 log10. Following photochemical treatment, SARS-CoV was consistently inactivated to the limit of detection in seven independent APC units. No infectious virus was detected after treatment when up to one-third of the APC unit was assayed, demonstrating a mean log10-reduction of >6.2. Potent inactivation of SARS-CoV therefore extends the capability of the INTERCEPT Blood System in inactivating a broad spectrum of human pathogens including recently emerging respiratory viruses.

Inactivation of viruses in platelet concentrates by photochemical treatment with amotosalen and long-wavelength ultraviolet light

BACKGROUND

Viral contamination of platelet (PLT) concentrates can result in transfusion-transmitted diseases. A photochemical treatment (PCT) process with amotosalen-HCl and long-wavelength ultraviolet light (UVA), which cross-links nucleic acids, was developed to inactivate viruses and other pathogens in PLT concentrates.

STUDY DESIGN AND METHODS

High titers of pathogenic or blood-borne viruses, representing 10 different families, were added to single-donor PLT concentrates containing 3.0 x 10(11) to 6.0 x 10(11) PLTs in approximately 300 mL of 35 percent plasma and 65 percent PLT additive solution (InterSol). After PCT with 150 micromol per L amotosalen and 3 J per cm(2) UVA, residual viral infectivity was assayed by sensitive cell culture or animal systems.

RESULTS

Enveloped viruses were uniformly sensitive to inactivation by PCT whereas nonenveloped viruses demonstrated variable inactivation. Log reduction of enveloped viruses for cell-free HIV-1 was >6.2; for cell-associated HIV-1, >6.1; for clinical isolate HIV-1, >3.4; for clinical isolate HIV-2, >2.5; for HBV, >5.5; for HCV, >4.5; for DHBV, >6.2; for BVDV, >6.0; for HTLV-I, 4.2; for HTLV-II, 4.6; for CMV, >5.9; for WNV, >5.5; for SARS-HCoV, >5.8; and for vaccinia virus, >4.7. Log reduction of nonenveloped viruses for human adenovirus 5 was >5.2; for parvovirus B19, 3.5->5.0; for bluetongue virus, 5.6-5.9; for feline conjunctivitis virus, 1.7-2.4; and for simian adenovirus 15, 0.7-2.3.

CONCLUSION

PCT inactivates a broad spectrum of pathogenic, blood-borne viruses. Inactivation of viruses in PLT concentrates with amotosalen and UVA offers the potential to prospectively prevent the majority of PLT transfusion-associated viral diseases.

Protecting the blood supply from emerging pathogens: the role of pathogen inactivation

Although the risk of infection by blood transfusion is relatively low, breakthrough infections still occur, Transfusion-related fatalities caused by infections continue to be reported, and blood is not tested for many potentially dangerous pathogens. The current paradigm for increasing the safety of the blood supply is the development and implementation of laboratory screening methods and restrictive donor criteria. When considering the large number of known pathogens and the fact that pathogens continue to emerge, it is clear that the utility of new tests and donor restrictions will continue to be a challenge when considering the cost of developing and implementing new screening assays, the loss of potential donors, and the risk of testing errors. Despite improving the safety of blood components, testing remains a reactive approach to blood safety. The contaminating organisms must be identified before sensitive tests can be developed. In contrast, pathogen inactivation is a proactive strategy designed to inactivate a pathogen before it enters the blood supply. Almost all pathogen inactivation technologies target nucleic acids, allowing for the inactivation of a variety of nucleic acid-containing pathogens within plasma, platelets, or red blood cells thus providing the potential to reduce transfusion-transmitted diseases. However, widespread use of a pathogen inactivation technology can only be realized when proven safe and efficacious and not cost-prohibitive.

Emerging infections in transfusion medicine

The risk of transfusion-transmitted infectious diseases (TTIDs) has declined dramatically in high-income nations over the past 2 decades, primarily because of extraordinary success in preventing HIV and other established transfusion-transmitted viruses from entering the blood supply. Despite this achievement, TTIDs remain a public health concern, and attention is refocusing on new and emerging pathogens, such as West Nile virus, infectious proteins (the presumed cause of variant Creutzfeldt-Jakob disease), and other transmissible organisms such as bacteria and parasites. In this article the authors concentrate on this heterogeneous group of infectious agents, describe individual pathogens and the risks they pose to transfusion recipients, and comment on existing and evolving procedures that are designed to protect the blood supply from this threat.

Photochemical treatment of platelet concentrates with amotosalen and long-wavelength ultraviolet light inactivates a broad spectrum of pathogenic bacteria

BACKGROUND

Bacterial contamination of platelet (PLT) concentrates can result in transfusion-transmitted sepsis. A photochemical treatment (PCT) process with amotosalen HCl and long-wavelength ultraviolet light (UVA), which cross-links nucleic acids, was developed to inactivate bacteria and other pathogens in PLT concentrates.

STUDY DESIGN AND METHODS

High titers of pathogenic aerobic and anaerobic Gram-positive bacteria (10 species), aerobic Gram-negative bacteria (7 species), and spirochetes (2 species) were added to single-donor PLT concentrates containing 3.0 x 10(11) to 6.0 x 10(11) PLTs in approximately 300 mL of 35 percent plasma and 65 percent PLT additive solution (InterSol, Baxter Healthcare) or saline. After PCT with 150 micro mol per L amotosalen and 3 J per cm(2) UVA, residual bacterial levels were detected by sensitive microbiologic methods.

RESULTS

The level of inactivation of viable bacteria was expressed as log reduction. Log reduction of Gram-positive bacteria for Staphylococcus epidermidis was > 6.6; for Staphylococcus aureus, 6.6; for Streptococcus pyogenes, > 6.8; for Listeria monocytogenes, > 6.3; for Corynebacterium minutissimum, > 6.3; for Bacillus cereus (vegetative), > 5.5; for Lactobacillus sp., > 6.4; for Bifidobacterium adolescentis, > 6.0; for Propionibacterium acnes, > 6.2; and for Clostridium perfringens, > 6.5. Log reduction of Gram-negative bacteria for Escherichia coli was > 6.4; for Serratia marcescens, > 6.7; for Klebsiella pneumoniae, > 5.6; for Pseudomonas aeruginosa, 4.5; for Salmonella choleraesuis, > 6.2; for Yersinia enterocolitica, > 5.9; and for Enterobacter cloacae, 5.9. Log reduction of spirochetes for Treponema pallidum was 6.8 to 7.0, and for Borrelia burgdorferi, > 6.9.

CONCLUSION

PCT inactivates high levels of a broad spectrum of pathogenic bacteria. The inactivation of bacteria in PLT concentrates offers the potential to prospectively prevent PLT-transfusion-associated bacteremia.

Photochemical treatment of platelet concentrates with amotosalen hydrochloride and ultraviolet A light inactivates free and latent cytomegalovirus in a murine transfusion model

BACKGROUND

A photochemical treatment (PCT) process utilizing amotosalen hydrochloride and long wavelength UVA light has been developed to inactivate pathogens in PLTs. This study investigated the effects of amotosalen/UVA treatment on free and latent murine CMV (MCMV) in PLT preparations using a murine model of transfusion-transmitted CMV (TT-CMV).

STUDY DESIGN AND METHODS

In a model of latent MCMV infection, "donor" mice received 1 x 10(6) plaque-forming units (PFUs) MCMV and were rested 14 days. Subsequently harvested, pooled, and washed WBCs were PCR positive for MCMV. Murine WBC doses of 1 x 10(4), 1 x 10(5), and 1 x 10(6) were added to human apheresis PLTs in 35 percent autologous plasma and 65 percent PLT AS (PAS). The WBC-PLT products were treated with 150 micro mol/L amotosalen and 0.6 J per cm2 UVA and transfused via tail vein injection into recipient mice. Recipients were killed on Day 14. Blood and spleens were collected and assayed for MCMV by PCR. In a parallel model of active infection with free virus, human PLT in 35 percent autologous plasma and 65 percent PAS were dosed with 1 x 10(5) and 1 x 10(6) PFUs of MCMV. All other procedures were as described above.

RESULTS

In the absence of amotosalen/UVA-pretreatment, transfusion of PLT latently or actively infected with MCMV produced TT-CMV in a dose-dependent fashion. In contrast, all transfusion recipients of identical PLT preparations pretreated with amotosalen/UVA were uniformly PCR negative for MCMV (abrogation of TT-CMV; p < 0.05).

CONCLUSIONS

PCT of PLT preparations with the specified doses of amotosalen hydrochloride and UVA light prevents transfusion transmission of free and latent MCMV in a murine model. These results suggest that PCT of human PLTs with amotosalen/UVA should also effectively abrogate TT-CMV in the clinical setting.