MAPT and infection: Importantly, transmissible tau can be generated not only in the brain but also by peripheral organs in response to an infection, including lung endothelial cells (Balczon et al., 2013, 2017, 2019; Choi et al., 2021), and has been shown to reduce dendritic spine density (Scott et al., 2020), impair learning and memory (Balczon et al., 2019), and cause neuronal tauopathy (Choi et al., 2021).