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A letter to the editor is presented in response to the article "A comparison of methods of pathogen inactivation of FFP," by G. Rock in the 2011 issue.

Background and objectives: Pathogen reduction of donor platelets with amotosalen/UVA has been shown to effectively inactivate pathogens and also contaminating white blood cells (WBCs). We wanted to determine whether WBC inactivation could also decrease alloimmune refractoriness to donor platelets. Materials and methods: Platelets were prepared from a donor dog's whole blood, and the platelets were either transfused without modification [standard (STD) platelets] or treated with amotosalen/UVA under conditions modelling the amotosalen/UVA Blood System for human platelets (APR) using either 4 or 3 J/cm2 of UVA exposure. Platelets were transfused weekly from a single donor dog for 8 weeks or until the recipient dog became refractory to their donor's platelets. Antibody samples were drawn weekly and tested against the donor dog's platelets and WBCs (CD8 and B cells). Results: Only 1/7 (14%) dogs that received STD platelets accepted 8 weeks of donor transfusions. Following APR 4 J/cm2 donor transfusions, 3/9 (33%) recipients accepted their donor's transfusions, but only one recipient remained antibody negative. Following APR 3 J/cm2 donor transfusions, the same dose as used for human platelet transfusions, 7/10 (70%) recipients accepted their donor's transfusions, but only two remained antibody negative. Conclusion: As a very high percentage of recipient dogs (70%) accepted APR 3 J/cm2 donor transfusions, these data suggest that preventing alloimmune platelet refractoriness may be another benefit of pathogen reduction using amotosalen/UVA. [ABSTRACT FROM AUTHOR]

Background and objectives: Chikungunya virus (CHIKV) infections have been reported in all continents, and the potential risk for CHIKV transfusion‐transmitted infections (TTIs) was demonstrated by the detection of CHIKV RNA‐positive donations in several countries. TTIs can be reduced by pathogen inactivation (PI) of blood products. In this study, we evaluated the efficacy of amustaline and glutathione (S‐303/GSH) to inactivate CHIKV in red‐blood‐cell concentrates (RBCs). Material and Methods: Red‐blood‐cells were spiked with high level of CHIKV. Infectious titres and RNA loads were measured before and after PI treatment. Residual CHIKV infectivity was also assessed after five successive cell culture passages. Results: The mean CHIKV titres in RBCs before inactivation was 5·81 ± 0·18 log10 50% tissue culture infectious dose (TCID50)/mL, and the mean viral RNA load was 10·49 ± 0·15 log10 genome equivalent (GEq)/mL. No CHIKV TCID was detected after S‐303 treatment nor was replicative CHIKV particles and viral RNA present after five cell culture passages of samples obtained immediately after S‐303 treatment. Conclusion: Chikungunya virus was previously shown to be inactivated by the PI technology using amotosalen and ultraviolet A light for the treatment of plasma and platelets. This new study demonstrates that S‐303/GSH can inactivate high titres of CHIKV in RBCs. [ABSTRACT FROM AUTHOR]

Background and Objectives Blood Centre logistics, staffing and donor scheduling may be optimized if pathogen inactivation ( PI) of platelets can be delayed until Day 1, but bacteria may rapidly grow during this time. This study evaluates bacterial PI performed 24 and 30 h after collection. Materials and Methods PAS-3 platelet units were collected on the Amicus and subsequently inoculated (3-53 CFU/unit) with 1of 5 transfusion relevant bacterial species ( n = 3/organism). Units were then stored for either 24 ± 0·3 or 30 ± 0·3 h at 20-24°C with agitation, subsequently treated with amotosalen and UVA, and stored for 7 days. Samples were taken before and after inactivation, on Days 2, 5 and 7 for BacT/ ALERT testing, and on Days 5 and 7 for plate counts. Results All samples from units taken prior to inactivation either demonstrated positive plate culture counts, or, in untreated positive controls, were culture-positive during storage. All contaminated units treated with amotosalen and UVA 24 after inoculation were culture-negative on all days tested. With inactivation performed 30 h following inoculation, one of 15 units (1-of-3 replicates) was culture-positive with Klebsiella pneumonia (1 × 109 CFU/ml) by Day 5. Conclusion Photochemical treatment did not inactivate 1 of 15 units to sterility in apheresis platelets stored in PAS with a 30-h delay between contamination and treatment, but did inactivate 15 of 15 units with a 24-h delay. [ABSTRACT FROM AUTHOR]