Neurotropic influenza virus infections

Abstract

Neurological complications of seasonal influenza virus (IV) infection are caused by the host immune response to IV infection because seasonal IV infections only affect the human respiratory epithelium and the viruses never invade the central nervous system (CNS). However, sporadic cases of human IV meningitis associated with highly pathogenic H5N1 have been reported since the late 1990s. The virulence of the H5N1 virus is largely due to mutation of the hemagglutinin gene, which mediates virus adsorption to host cells. The highly pathogenic H5N1 virus directly spreads from the nasal cavity via the olfactory nerve to the CNS in animal models.