Dissecting the localization of Tilapiatilapinevirus in the brain of the experimentally infected Nile tilapia, Oreochromisniloticus (L.)

Abstract

Tilapia tilapinevirusor tilapia lake virus (TiLV) is an emerging virus that inflicts significant mortality on farmed tilapia globally. Previous studies reported detection of the virus in multipleorgans ofthe infected fish; however, little is known about the in-depth localization of the virus in the central nervous system. Herein, we determined thedistribution of TiLVin the entire brain ofexperimentallyinfected Nile tilapia. In situhybridization (ISH) using TiLV-specific probes revealed that the virus was broadly distributed throughout the brain. The strongest positive signals were dominantly detected in the forebrain (responsible for learning, appetitive behaviour and attention) and the hindbrain (involved in controlling locomotion and basal physiology). The permissive cell zones for viral infection were observed mostly to be along the blood vessels and the ventricles. This indicates that the virus may productively enter into the brain through the circulatory system and widen broad regions, possibly through the cerebrospinal fluid along the ventricles, and subsequently induce the brain dysfunction. Understanding the pattern of viral localization in the brain may help elucidate the neurologicaldisordersof the diseased fish.This study revealed the distribution of TiLV in the whole infected brain, providing new insights into fish-virusinteractions and neuropathogenesis.