AQP4 and neuromyelitis optica: Recurrent NMO associated with HTLV-1 infection has been reported (Olindo et al., 2010), and basic research has shown that latent HTLV-1 infection could lead to TAX1BP1 antigen presentation and the production of anti-AQP4 antibodies through T-cell-mediated mechanisms (Kampylafka et al., 2015).