title: Viral Infection of the Central Nervous System and Neuroinflammation Precede Blood-Brain Barrier Disruption during Japanese Encephalitis Virus Infection.
abstract: Japanese encephalitis is an acute zoonotic, mosquito-borne disease caused by Japanese encephalitis virus (JEV). Japanese encephalitis is characterized by extensive inflammation in the central nervous system (CNS) and disruption of the blood-brain barrier (BBB). However, the pathogenic mechanisms contributing to the BBB disruption are not known. Here, using a mouse model of intravenous JEV infection, we show that virus titers increased exponentially in the brain from 2 to 5 days postinfection. This was accompanied by an early, dramatic increase in the level of inflammatory cytokines and chemokines in the brain. Enhancement of BBB permeability, however, was not observed until day 4, suggesting that viral entry and the onset of inflammation in the CNS occurred prior to BBB damage. In vitro studies revealed that direct infection with JEV could not induce changes in the permeability of brain microvascular endothelial cell monolayers. However, brain extracts derived from symptomatic JEV-infected mice, but not from mock-infected mice, induced significant permeability of the endothelial monolayer. Consistent with a role for inflammatory mediators in BBB disruption, the administration of gamma interferon-neutralizing antibody ameliorated the enhancement of BBB permeability in JEV-infected mice. Taken together, our data suggest that JEV enters the CNS, propagates in neurons, and induces the production of inflammatory cytokines and chemokines, which result in the disruption of the BBB.
  
  
  OBJECTIVE
  Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia, resulting in 70,000 cases each year, in which approximately 20 to 30% of cases are fatal, and a high proportion of patients survive with serious neurological and psychiatric sequelae. Pathologically, JEV infection causes an acute encephalopathy accompanied by BBB dysfunction; however, the mechanism is not clear. Thus, understanding the mechanisms of BBB disruption in JEV infection is important. Our data demonstrate that JEV gains entry into the CNS prior to BBB disruption. Furthermore, it is not JEV infection per se, but the inflammatory cytokines/chemokines induced by JEV infection that inhibit the expression of TJ proteins and ultimately result in the enhancement of BBB permeability. Neutralization of gamma interferon (IFN-γ) ameliorated the enhancement of BBB permeability in JEV-infected mice, suggesting that IFN-γ could be a potential therapeutic target. This study would lead to identification of potential therapeutic avenues for the treatment of JEV infection.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Fang
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Yueyun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Lan
authors.initials: L
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Shengbo
authors.initials: S
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Jiaolong
authors.initials: J
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Chong
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China.
authors.forename: Kunlun
authors.initials: K
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China cuimin@mail.hzau.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People's Republic of China Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
authors.forename: Zhen F
authors.initials: ZF
authors.lastname: Fu
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000008:administration & dosage; D001812:Blood-Brain Barrier / Q000276:immunology / Q000473:pathology / Q000821:virology*; D002199:Capillary Permeability; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D002490:Central Nervous System / Q000276:immunology / Q000473:pathology / Q000821:virology*; D018925:Chemokines / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis; D004195:Disease Models, Animal; D018349:Encephalitis Viruses, Japanese / Q000472:pathogenicity / Q000502:physiology; D004672:Encephalitis, Japanese / Q000276:immunology / Q000473:pathology / Q000821:virology*; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D013997:Time Factors; D014779:Virus Replication
chemical_list: D057134:Antibodies, Neutralizing; D015815:Cell Adhesion Molecules; D018925:Chemokines; D016207:Cytokines; D018836:Inflammation Mediators; D007371:Interferon-gamma