Phosphatidylserine receptors TIM-1 and AXL mediate tick-borne Powassan virus entry

Powassan virus (POWV) is an emerging tick-borne neurotropic human pathogen. Currently, there are no approved medications or vaccines available. The goal of this study is to investigate the receptor usage for POWV, which can be a potential therapeutic target. For this purpose, we used cell culture-based models including neuronal cells, 293T cells stably expressing different viral entry receptors, and induced pluripotent stem cell (iPSC)-derived cortical organoids, as well as <i>in vivo</i> studies in wild-type C57BL/6 mice. Among the receptors studied, phosphatidylserine (PtdSer)-recognizing TIM-1 and AXL receptors facilitated higher infection. To further validate our findings, a neutralization assay was performed in which the soluble form of the TIM-1 receptor efficiently blocked infection. In addition, we demonstrated that PtdSer receptor-expressing cells in cortical organoids and mouse brain tissues were infected with the virus. We conclude that PtsSer moieties on POWVs' surface facilitate viral entry through the cellular TIM-1 and AXL receptors.