Cerus Corporation, Concord, CA, USA Concord, California, United States
Background/Case Studies: Since late 2023, outbreaks of Oropouche virus (OROV) have been documented in South America and the Caribbean, prompting the CDC to issue a level 2 travel health notice in some regions. This outbreak has again highlighted the risk of arthropod-borne viruses to blood supply sustainability and safety, even in areas not directly impacted by the outbreak, as travel-associated cases have already been confirmed in regions of North America and Europe. California encephalitis virus (CEV), along with OROV, is part of the Orthobunyavirus genus, in the family Peribunyaviridae. CEV, like OROV, is a negative sense, single-stranded RNA virus that is transmitted to humans through the bite of an infected mosquito. Although CEV and OROV belong to separate serogroups, they have similarities in their genome and virion structure as members of the same genus. Though CEV infection in humans is relatively rare, it was used as a representative for orthobunyaviruses to determine the efficacy of the amotosalen and UVA (AMO-UVA) pathogen reduction technology (PRT) to mitigate the increased risks associated with the growing OROV outbreak.
Study
Design/Methods: Spiking and inactivation experiments with CEV were performed using the INTERCEPT® Blood System for Platelets PRT. Eight replicates were performed, four in platelet concentrates (PC) suspended in 100% plasma and four in PC suspended in 35% plasma/65% platelet additive solution (PAS). For each replicate, PC from individual donors were adjusted to approximately 285mL. Each replicate was contaminated with CEV to achieve a titer of approximately 4 log pfu/mL in each platelet unit. After contamination, each replicate was dosed with approximately 150 mM amotosalen and a pre-treatment control sample (pre-UVA) was taken. Each unit was then treated with a single target dose of 3.6J/cm2 UVA and a post-treatment sample (post-UVA) was taken. The Vero76 cell-based plaque assay system was used to determine the pre- and post-UVA viral titers. The log reduction factor was calculated based on the difference between the log pfu/mL values in the pre- and post-UVA samples.
Results/Findings: The table shows the average log reduction factor for CEV achieved in both PC suspended in 100% plasma and in 35% plasma/65% PAS using AMO-UVA PRT.
Conclusions: Treatment with AMO-UVA PRT inactivated 3.9 log pfu/mL of CEV in PC suspended in 100% plasma and 4.5 log pfu/mL of CEV in PC suspended in 35% plasma/65% PAS. These results indicate that AMO-UVA treatment effectively inactivates CEV in platelet components. Considering the similar genome and virion structure between CEV and OROV, these results suggest that AMO-UVA PRT may also be effective in reducing the risk of OROV transfusion transmitted infections.
