Studies On Epidemiological Investigation And Immune Cross-protection Effect Of West Nile Virus And Japanese Encephalitis Virus Infections

West Nile fever and encephalitis caused by West Nile virus (WNV) is maintained in a natural transmission cycle involving mosquito vectors and bird reservoir hosts, with the fatality of 4%～11%. Although no case of the disease have been reported in China, enough attention should be paid to the possible presence of WNV infection due to existence of potential vectors and animal hosts.The epidemiology surveys on WNV and Japanese encephalitis virus (JEV) infections in potential vectors,animals and human beings were carried out in Beijing, Xinjiang, Yunnan, Fujian, Zhejiang, Inner Mongolia, Jilin, Heilongjiang and Guizhou. No WNV infection was detected in mosquitoes, ticks, rodents, bats and the serum of human beings. Cross-reaction between WNV and JEV was discovered. The antibodies against JEV, WNV and genus Flavivirus were detected in the survey areas with a overall positve rate of 27.4%. Further study on cross-protection effect between the two viruses was carried out using experimental animals. The sera obtained from the mice immunized with attenuated JE vaccine could neutralize WNV in C6/36. To distinguish WNV infection from JEV infection, an enzyme-linked immune assay (ELISA) using recombined antigen was developed with high specificity.Our findings indicate that antibodies to JEV may effectively protect humans from WNV infection, and WNV infection transmission may be limited because JE vaacination is universal in China.