Assurance of neuroattenuation of a live vaccine against West Nile virus: a comprehensive study of neuropathogenesis after infection with chimeric WN/DEN4Δ30 vaccine in comparison to two parental viruses and a surrogate flavivirus reference vaccine.

•Availability of West Nile virus vaccine could be of benefit to aging population.•Study of neuropathogenesis after infection with WN/DEN4Δ30 vaccine was performed.•WN/DEN4Δ30 was compared to two parental viruses and a surrogate reference vaccine.•Results show that our vaccine is highly neuroattenuated for nonhuman primates.•WN/DEN4Δ30 vaccine should be further evaluated in clinical trials in older adults.