Over 110 million units of blood are collected yearly worldwide.[1] Notwithstanding the current screening and prevention procedures, the risk of transmission of infectious diseases via blood products and plasma derivatives is a major public health concern.[2] Safety of blood supply using donor screening and laboratory testing is limited because it requires knowledge of possible infectious agents, effective laboratory tests for each agent and application of that testing to all collected blood. Therefore, it has been a long-sought goal to find a cost-effective way to sterilise blood after collection using a PI technology. Also, the impact of global warming may have a serious impact on the necessity to implement effective PI technology. As temperatures rise, the transmission of vector-borne pathogens may increase dramatically. As a direct consequence, we may need to rely increasingly on PI technology in the future.[3]
For plasma and platelets, various costly PI techniques are available: Solvent/Detergent techniques and photochemical inactivation techniques, using methylene blue, amotosalen/UVA or riboflavin/UVB.[2] All with its own limitations like the damaging of platelets (and RBCs) by UV light [2] and risk of contamination caused by handling of RBC concentrates. No PI techniques are available on the market yet for RBC concentrates. However, phase III trials are running for Mirasol® and INTERCEPT® with RBCs, using riboflavin/UVB and a frangible anchor linker effector, respectively.[1]
γ-irradiation has been demonstrated to be able to inactivate viruses [4-11] and is routinely used for decontaminating tissue allografts.[6,7,11] However, γ-irradiation is known to damage RBCs, as well.[13,14] Certain reports address the fact that the amount of irradiation needed to achieve the SAL of viruses would be too high (15-34 kGy) for the blood products, causing too much damage to RBCs.[5-10,12] However, in these reports inhomogeneous irradiation was used which allows for inconsistent measurements and uncertainty of results. By using homogenous irradiation we hypothesise that much lower doses can be used to achieve SAL, without damaging the RBCs. RBC products are already incidentally being irradiated with 25 Gy for T-cell inactivation for certain haemato-oncological patients.[15] This, however is inhomogeneous irradiation. 25 Gy is the maximum dose of irradiation that should be used on RBC products, since studies report that 25 Gy or more of γ-irradiation can negatively affect RBC products.[13,14] If homogeneous irradiation with ≤25 Gy could achieve SAL with relative little damage to the blood product, PI of RBC can be achieved with a simple and cheap technique which could reduce health costs dramatically. Therefore, we believe it is of great interest to investigate whether homogeneous irradiation can eradicate viruses in blood in doses agreeable to preserve quality of blood products. Schmidt et al. reported that HIV-1 is resistant to irradiation. A relative high dose of inhomogeneous irradiation was needed in various media to achieve SAL for HIV-1.[5,7] Therefore it appears that HIV-1 is a good model virus to use for this pilot study. A standard dose of homogeneous irradiation should be capable to inactivate HIV-1, whereas a standard dose of inhomogeneous irradiation is not. We hypothesised, therefore, that 25 Gy of homogenous γ-irradiation is capable of eradicating HIV-1 RNA from a plasma sample.