Shawn D. Keil

Photochemical inactivation of selected viruses and bacteria in platelet concentrates using riboflavin and light

BACKGROUND:  A medical device is being developed for the reduction of pathogens in PLT concentrates (PCs). The device uses broadband UV light and the compound riboflavin (vitamin B2).

Riboflavin and UV-Light Based Pathogen Reduction: Extent and Consequence of DNA Damage at the Molecular Level

Abstract We are developing a technology based on the combined application of riboflavin (RB) and light for inactivating pathogens in blood products while retaining the biological functions of the treated cells and proteins. Virus and bacteria reduction measured by tissue culture infectivity or colony formation with UV light alone and in combination with RB yield equivalent results. The effects of RB as a sensitizing agent on DNA in white cells, bacteria and viruses in combination with UV light exposure have been evaluated. UV-mediated DNA degradation in Jurkat T cells and leukocytes in plasma as measured by the FlowTACS assay was significantly increased in the presence of RB. Agarose gel electrophoretic analysis of DNA in Escherichia coli and leukocytes in plasma demonstrated enhanced DNA degradation in the presence of RB. UV light in combination with RB prevented the reactivation of lambda phage compared with samples irradiated in the absence of RB. UV-mediated oxidative damage in calf thymus DNA was also enhanced in the presence of RB. These observations clearly demonstrate that the presence of RB and UV light selectively enhances damage to the guanine bases in DNA. These data also suggest that the type and extent of damage to DNA for virus in the presence of RB and light make it less likely to be repaired by normal repair pathways available in host cells.

A laboratory comparison of pathogen reduction technology treatment and culture of platelet products for addressing bacterial contamination concerns

BACKGROUND: Concerns over the risk of bacterial contamination of platelet products have led to implementation of bacteria culture and other screening methods. New approaches for dealing with this issue have also been proposed.

Treatment with riboflavin and ultraviolet light prevents alloimmunization to platelet transfusions and cardiac transplants

Background. Functional leukocytes in blood transfusions can cause alloimmunization. Previous studies have shown that exposure of platelet concentrates to riboflavin and light (Mirasol PRT treatment) causes irreparable modification of nucleic acids. This treatment does not interfere with platelet function but does inhibit a wide range of immunological functions of leukocytes present in platelet concentrates. The current study evaluated the ability of Mirasol treatment to prevent alloimmunization by platelet transfusions in rats. Methods. Lewis rats received eight transfusions of untreated or Mirasol-treated platelets containing leukocytes from DA rats. Animals were subsequently challenged with a heart transplant under cyclosporine treatment. Results. Mirasol treatment caused apoptosis of the leukocytes as measured by annexin V and CD45 staining. Complement split products were deposited on the apoptotic bodies in the platelet pack. The primary and secondary immunoglobulin (Ig) M and IgG responses in rats that received Mirasol-treated platelets were almost completely abolished compared to animals that received untreated platelets. Untreated platelet transfusions elicited strong IgG responses that were associated with rapid rejection of subsequent heart transplants. Rejected hearts contained macrophage infiltrates and C4d deposits. In contrast, no grafts were rejected by recipients transfused with Mirasol-treated platelets. Macrophage infiltrates and C4d deposits were decreased in these grafts. Recipients that were presensitized to untreated platelets were capable of producing a memory response to Mirasol-treated platelets that caused accelerated rejection of subsequent transplants. Conclusions. Transfusions of platelets that were treated with riboflavin and ultraviolet light prevented presensitization to transplants. However, Mirasol-treated platelets were immunogenic in presensitized recipients.

Photochemical inactivation of chikungunya virus in plasma and platelets using the Mirasol pathogen reduction technology system

BACKGROUND: Chikungunya virus (CHIKV) is a reemerging mosquito‐borne virus that has been responsible for a number of large‐scale epidemics as well as imported cases covering a wide geographical range. As a blood‐borne virus capable of mounting a high‐titer viremia in infected humans, CHIKV was included on a list of risk agents for transfusion and organ transplant by the AABB Transfusion‐Transmitted Diseases Committee. Therefore, we evaluated the ability of the Mirasol pathogen reduction technology (PRT) system (CaridianBCT Biotechnologies) to inactivate live virus in contaminated plasma and platelet (PLT) samples.

Defining “adequate” pathogen reduction performance for transfused blood components

Pathogen reduction of labile blood products offers the opportunity to introduce to the blood banking community the same mechanism of protection that is employed for fractionated or pooled plasma products today—blood components that have been treated with methods to inactivate or reduce the infectivity of a variety of organisms that may contaminate donated blood and thus potentially transmit infection via transfusion. Due to the mechanisms of action, the methods employed in the plasma fractionation environment are not directly applicable to labile blood products. This article examines whether the same criteria of performance required for plasma derivatives (i.e., 6 log/mL reduction by multiple orthogonal methods) should be applied to the treatment of labile components and if not what criteria for performance might be sufficient. In conducting this analysis, we have considered what has been learned in the past several decades regarding the dynamics and infectivity of various pathogens and disease transmission by blood products, the introduction and progressive enhancement of testing methods based on serology and nucleic acid testing, and the performance characteristics for pathogen reduction technologies that are available today.

Evaluating pathogen reduction of Trypanosoma cruzi with riboflavin and ultraviolet light for whole blood

BACKGROUND: Trypanosoma cruzi, the protozoan parasitic agent of Chagas disease, can be transmitted by blood transfusion. In 2007, most US blood banks started screening blood donations for T. cruzi, but the cost and perceived need of the test have been the subject of ongoing discussion. In this study, we evaluated the ability of the Mirasol System (CaridianBCT), which uses riboflavin (RB) and ultraviolet light to inactivate pathogens, to reduce the levels of infectious T. cruzi in whole blood (WB).

Development of a riboflavin and ultraviolet light‐based device to treat whole blood

In the United States, blood components are commonly used for patients in need of massive transfusion after blood loss. In combat situations, when severe traumatic injuries occur far from a hospital, fresh whole blood is a valuable transfusion therapy because components may not be available. The risk of infectious or immunological complications from fresh whole blood transfusions could be mitigated by a system that reduces pathogen loads and inactivates white blood cells (WBCs). Such a system is in development and utilizes riboflavin and ultraviolet light to provide pathogen reduction and WBC inactivation.

Riboflavin and ultraviolet light reduce the infectivity of Babesia microti in whole blood.

BACKGROUND: Babesia microti is the parasite most frequently transmitted by blood transfusion in the United States. Previous work demonstrated the efficacy of riboflavin (RB) and ultraviolet (UV) light to inactivate B. microti in apheresis plasma and platelet units. In this study we investigated the effectiveness of RB and UV light to reduce the levels of B. microti in whole blood (WB).

Inactivation of Plasmodium spp. in plasma and platelet concentrates using riboflavin and ultraviolet light

Photochemical treatment of blood products could help prevent transfusion‐transmitted malaria and reduce the need for donor deferrals. In this study we evaluated the effectiveness of riboflavin and ultraviolet (UV) light against both Plasmodium falciparum, which causes the most severe form of human malaria, and Plasmodium yoelii, an in vivo murine model for malaria.