BACKGROUND:The potential for Zika virus (ZIKV) transfusion-transmission (TT) has been demonstrated in French Polynesia and Brazil. Pathogen inactivation (PI) of blood products is a proactive strategy to inactivate TT pathogens including arboviruses. Inactivation of West Nile, dengue, Zika, and chikungunya viruses was previously demonstrated by photochemical treatment with amotosalen and ultraviolet A (UVA) illumination. In this study, we evaluated ZIKV inactivation in red blood cell (RBC) components by a chemical approach that uses amustaline (S-303) and glutathione (GSH). STUDY DESIGN AND METHODS: RBC componentswere spiked with a high titer of ZIKV. Viral titers (infectivity) and ZIKV RNA loads (reverse transcriptionpolymerase chain reaction) were measured in spiked RBCs before and after S-303 and GSH treatment and confirmed using repetitive passages in cell culture. A mock-treated arm validated the approach by demonstrating stability of the virus (infectivity and RNA load) during the process. RESULTS:The mean ZIKV infectivity titer and RNA load in RBCs were 5.99 6 0.2 log 50% tissue culture infectious dose (TCID 50 )/mL and 7.75 6 0.16 log genomic equivalents/mL before inactivation. No infectivity was detected immediately after S-303 and GSH treatment and after five serial passages in cell culture. CONCLUSION:Complete ZIKV inactivation of more than 5.99 log TCID 50 /mL in RBCs was achieved using S-303 and GSH at levels higher than those found in asymptomatic ZIKV-infected blood donors. Therefore, the S-303 and GSH PI system is promising for mitigating the risk of ZIKV TT. US areas with active ZIKV circulation, the main recommendations included donor deferral, blood collection suspension, and importation of blood components from nonactive transmission areas and either implementation of ZIKV nucleic acid testing (NAT) or pathogen inactivation (PI). PI is a proactive strategy designed to reduce or eliminate infectivity of bacteria, viruses, and parasites in blood. 35 Several processes have been developed for the inactivation of pathogens in fresh-frozen plasma and platelet (PLT) concentrates. 35In FP, the INTERCEPT Blood System for PLTs (Cerus Corporation), a CE mark-approved technology, was implemented in 2010 and has since been used routinely. During the FP ZIKV outbreak, plasma units were imported from metropolitan France. 22 However, during the outbreak, no PI technology was commercially available for red blood cell (RBC) treatment.The INTERCEPT Blood System for RBCs uses a chemical treatment with the small molecule amustaline (S-303) that forms covalent crosslinks and adducts with nucleic acids resulting in the inactivation of pathogens. S-303 is a reactive modular compound that is designed to react quickly and then decompose by hydrolysis to the nonreactive compound S-300 (Fig. 1). It is formulated in the presence of the natural tripeptide glutathione (GSH) to quench unreacted side reactions. S-303 has been shown to inactivate a variety of enveloped and nonenveloped viruses, Gram-positive and -negative b...

BACKGROUND Concerned over the risk of Zika virus (ZIKV) transfusion transmission, public health agencies recommended the implementation of mitigation strategies for its prevention. Those strategies included the use of pathogen inactivation for the treatment of plasma and platelets. The efficacy of amotosalen/ultraviolet A to inactivate ZIKV in plasma had been previously demonstrated, and the efficacy of inactivation in platelets with the same technology was assumed. These studies quantify ZIKV inactivation in platelet components using amotosalen/ultraviolet A. STUDY DESIGN AND METHODS Platelet components were spiked with ZIKV, and ZIKV infectious titers and RNA loads were measured by cell culture‐based assays and real‐time polymerase chain reaction in spiked platelet components before and after photochemical treatment using amotosalen/ultraviolet A. RESULTS The mean ZIKV infectivity titers and RNA loads in platelet components before inactivation were either 4.9 log10 plaque forming units per milliliter, or 4.4 log10 50% tissue culture infective dose per milliliter and 7.5 log10 genome equivalents per milliliter, respectively. No infectivity was detected immediately after amotosalen/ultraviolet A treatment. No replicative virus remained after treatment, as demonstrated by multiple passages on Vero cell cultures; and ZIKV RNA was not detected from the first passage after inactivation. Additional experiments in this study demonstrated efficient inactivation to the limit of detection in platelets manufactured in 65% platelet additive solution, 35% plasma, or 100% plasma. CONCLUSION As previously demonstrated for plasma, robust levels of ZIKV inactivation were achieved in platelet components. With inactivation of higher levels of ZIKV than those reported in asymptomatic, RNA‐reactive blood donors, the pathogen‐inactivation system using amotosalen/ultraviolet A offers the potential to mitigate the risk of ZIKV transmission by plasma and platelet transfusion.

BACKGROUND Dengue virus (DENV) is an arbovirus primarily transmitted through mosquito bite; however, DENV transfusion‐transmitted infections (TTIs) have been reported and asymptomatic DENV RNA–positive blood donors have been identified in endemic countries. DENV is considered a high‐risk pathogen for blood safety. One of the mitigation strategies to prevent arbovirus TTIs is pathogen inactivation. In this study we demonstrate that the amustaline and glutathione (S‐303/GSH) treatment previously found effective against Zika virus in red blood cells (RBCs) is also effective in inactivating DENV. STUDY DESIGN AND METHODS Red blood cells were spiked with high levels of DENV. Viral RNA loads and infectious titers were measured in the untreated control and before and after pathogen inactivation treatment of RBC samples. DENV infectivity was also assessed over five successive cell culture passages to detect any potential residual replicative virus. RESULTS The mean ± SD DENV titer in RBCs before inactivation was 6.61 ± 0.19 log 50% tissue culture infectious dose (TCID50)/mL and the mean viral RNA load was 8.42 log genome equivalents/mL. No replicative DENV was detected either immediately after completion of treatment using S‐303/GSH or after cell culture passages. CONCLUSION Treatment using S‐303/GSH inactivated high levels of DENV in RBCs to the limit of detection. In combination with previous studies showing the effective inactivation of DENV in plasma and platelets using the licensed amotosalen/UVA system, this study demonstrates that high levels of DENV can be inactivated in all blood components.

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.

BACKGROUND The reemergence of yellow fever virus (YFV) in Africa and Brazil, and massive vaccine campaigns triggered to contain the outbreaks, have raised concerns over blood transfusion safety and availability with increased risk of YFV transfusion‐transmitted infections (TTIs) by native and vaccine‐acquired YFV. Blood donor deferral for 2 to 4 weeks following live attenuated YFV vaccination, and deferral for travel to endemic/epidemic areas, may result in blood donor loss and impact platelet component (PC) stocks. This study investigated the efficacy of INTERCEPT Blood System pathogen reduction (PR) with use of amotosalen and ultraviolet A (UVA) light to inactivate high levels of YFV in PCs. MATERIALS Four units of apheresis platelets prepared in 35% plasma/65% platelet additive solution (PC‐PAS) and 4 units of PC in 100% human plasma (PC‐Plasma) were spiked with high infectious titers of YFV (YFV‐17D vaccine strain). YFV‐17D infectious titers were measured by plaque assay and expressed as plaque‐forming units (PFU) before and after amotosalen/UVA treatment to determine log reduction. RESULTS The mean YFV‐17D infectious titers in PC before inactivation were 5.5 ± 0.1 log PFU/mL in PC‐PAS and 5.3 ± 0.1 log PFU/mL in PC‐Plasma. No infectivity was detected immediately after amotosalen/UVA treatment. CONCLUSION The amotosalen/UVA PR system inactivated high titers of infectious YFV‐17D in PC. This PR technology could reduce the risk of YFV TTI and help secure PC supplies in areas experiencing YFV outbreaks where massive vaccination campaigns are required.