Japanese Encephalitis is a disease caused by the mosquito-borne Japanese Encephalitis Virus (JEV). JE is a mosquito-borne viral infection of the central nervous system in humans and animals, specifically horses and cattle. Infectious mosquito can spread the virus to humans when humans were bitten. Japanese Encephalitis can cause fever, headache, confusion, seizures, and, in some cases, death.
Japanese encephalitis virus (JEV) is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific. JEV is a flavivirus, which is closely related to Dengue, Yellow Fever and West Nile Encephalitis. There are five genotypes and one serotype of JEV: GI-GV. Genotypes GIb and GII are associated with temperate climates. GIb is believed to be the dominant JEV genotype in Asia. The genomic RNA of JEV encodes a single long open reading frame(ORF), and a polyprotein translated from the genome is cleaved co- and posttranslationally by host and viral proteases to yield 3 structural proteins: the core, precursor membrane (prM), and envelope (E) proteins, and seven nonstructural proteins, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5.
Fig.1 Electron micrograph of Japanese Encephalitis Virus particles
Japanese encephalitis virus (JEV) is an enveloped, single-stranded RNA virus, it belongs to the genus Flavivirus within the family Flaviviridae. Generally, JEV occurs as a single serotype, but considerable antigenic variation is also observed. Scientists have been isolated more than 50 strains in Japan. There are several diagnostic methods to detect JEV. According to a latest report, more and more scientists prefer to use fewer materials and less technical skills to detect the virus. More attention was given to PCR, RT-LAMP, ELISA, and immunochromatography. Flavivirus-specific monoclonal antibodies can also be used to detect JEV antigen in serum, and immunohistochemistry (IHC) can be used to detect JEV antigen in fetal tissues. Meanwhile, serological tests which including immunofluorescent antibody (IFA), virus neutralization (VN), complement fixation (CF), hemagglutination inhibition (HI), and ELISA can be used to establish the prevalence of infection in a population or individual diagnosis purpose. Therefore, serological diagnoses should be carried out very careful because cross-reactivity with other flaviviruses might occur and the maternal antibodies may be present for up to 8 weeks in piglets.