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 B(2)). STUDY DESIGN AND METHODS: Pathogens were added to single-donor PLTs. After treatment, the infectivity of each pathogen was measured using established biologic assays. In vitro PLT performance was evaluated after treatment and after 5 days of storage using a panel of 10 in-vitro cell quality assays. RESULTS: In studies with viral pathogens, the Pathogen Reduction Technology (PRT) system provided average log reduction factors of 4.46 +/- 0.39 for intracellular HIV, 5.93 +/- 0.20 for cells associated HIV, and 5.19 +/- 0.50 for West Nile virus. For the nonenveloped porcine parvovirus, a reduction factor greater than 5.0 log was observed. Staphylococcus epidermidis and Escherichia coli bacteria were also tested with observed reduction factors to the limits of detection of 4.0 log or greater. PLT cell quality was adequately maintained after treatment and during storage. Although P-selectin expression, glucose consumption, and lactate production increased relative to controls, this was not beyond accepted levels. The pH of treated PCs also decreased slightly relative to control PLTs on Days 1 and 5. CONCLUSION: The data indicate that the device successfully reduced the number of selected pathogens in PCs. Despite the fact that significant differences exist between treated and control in-vitro variables, it is speculated that the clinical effectiveness of both products will not be significantly different, based on comparison to historical data for products in routine clinical use today.

Controlled gamma-irradiation mediated pathogen inactivation of human urokinase preparations with significant recovery of enzymatic activity.

Human sources of urokinase have led to the contamination of in-process lots of commercially available material with human pathogens. Effective pathogen inactivation of urokinase preparations can be achieved through the use of gamma-irradiation. Additionally, the presence of a free radical scavenger (ascorbate) and the control of temperature have resulted in maintenance of the enzymatic activity of urokinase without a significant effect on the pathogen inactivation properties of gamma-irradiation. In this study we have optimized the conditions during gamma-irradiation to achieve inactivation of porcine parvovirus by 5 logs and vaccinia virus to levels below the limits of detection, while maintaining 92% of urokinase activity. Product specific optimization of gamma-irradiation has the potential to provide effective pathogen inactivation while maintaining substantial functional activity for many therapeutic proteins.

Effective use of gamma irradiation for pathogen inactivation of monoclonal antibody preparations.

Gamma irradiation has been used for decades as an effective method of pathogen inactivation of relatively inert materials. Until recently, its application to biologicals has resulted in unacceptable losses in functional activity. In this report we demonstrate that the damaging secondary effects of gamma irradiation can be controlled while maintaining the pathogen inactivation properties due to damage by primary effects. Control is achieved by a combination of protection from free radical damage to a monoclonal antibody through the use of the antioxidant ascorbate and by freeze-drying to minimize the potential for generating free radicals. The data demonstrate a synergy of these two approaches that results in quantitative recovery of functional activity while maintaining the ability to inactivate greater than 5 logs of porcine parvovirus infectivity.