V. VIRUS REPLICATION
A. Mode of Transmission
The transmission of JEV in mainly through a vector, the Culicine mosquitoes primarily Culex tritaneurinchus. In the Phillipines it breeds in the vast expance of ricefeilds. In nature, JEV is maintained in the amplifying host, hogs and domestic birds. Humans and vertebrates are incidental hosts. JEV is transovaially passed in the Culex mosquitoes (Chan1999).
Japanese encephalitis virus is also transmitted naturally between wild and domestic birds,and pigs by Culex mosquitoes. Although many animals can be infected with the virus,only those which develop high viraemias are important in the natural cycle. As well as maintaining and amplifying Japanese encephalitis virus in the environment, birds may also be responsible for the spread to new geographical areas. Pigs are the most important natural host for transmission to humans, because they are often kept close to humans, have prolonged and high viraemias, and produce many offspring—thus providing a continuous supply of previously uninfected new hosts(Solomon,Dung,Kneen,et al).