Cross Protection Of NIS Protein Of West Nile Virus Against Japanese Encephalitis Virus

West Nile virus (WNV) and Japanese encephalitis virus (JEV) are two associated agents ofzoonosis. The NS1(nonstructural protein1) is an important protein that can elicit non-neutralized,protective immune responses during infection of animals. It is of great significance to characterize themolecular basis of WNV NS1specific antibody responses and evaluate the effect of cross protectionagainst JEV, in order to further develop new diagnostic tools and cross protective vaccines.In the present study we used purified WNV NS1protein which expressed from baculovirusesimmunized Balb/c mice, and successfully developed eight WNV NS1specific monoclonal antibodies(mAbs) and mouse antisera (polyclonal antibodies, pAbs). We screened eight NS1-specific mAbs andantisera for reactivity against35partially overlapping peptides covering the entire WNV NS1protein.The screen identified four WNV-specific epitopes using mAbs, located at positions amino acid residues(aa)21-36,101-116,191-206and261-276in WNV NS1protein. But using pAbs, only three WNVspecific epitopes were identified, located at positions101-116,191-206and231-246aa. Two of them(21-36and261-276aa) had different reactivity with respective mAbs and pAbs.Certain species of birds, including crows, house sparrows and geese are considered highlysusceptible hosts to WNV. Because they are close to contact with poultry, such as chicken, duck andgoose which are also susceptible hosts to WNV, the poultry easily infect WNV and transmit it to humancausing the panic of public health. The present study describes comprehensive mapping of commonimmunodominant linear B-cell epitopes in the WNV NS1protein using avian WNV NS1antisera. Wescreened antisera from chickens, ducks and geese immunized with purified NS1protein for reactivityagainst35partially overlapping peptides covering the entire WNV NS1protein. This study identifiedtwelve, nine and six peptide epitopes recognized by chicken, duck and goose antibody responses,respectively. Three epitopes (NS1-3,14and24) were recognized by antibodies elicited byimmunization in all three avian species tested. We also found that NS1-3and24were WNV-specificepitopes, whereas the NS1-14epitope was conserved among the Japanese encephalitis (JE) serocomplexviruses based on the reactivity of avian WNV NS1antisera against polypeptides derived from the NS1sequences of viruses of the JE serocomplex. Further analysis showed that the three common polypeptideepitopes were not recognized by antibodies in Avian Influenza Virus (AIV), Newcastle Disease Virus(NDV), Duck Plague Virus (DPV) and Goose Parvovirus (GPV) antisera.Base on the previous finding, we know there are many JE serocomplex B-cell epitopes in WNVNS1protein, so we also want to expound if it is effective to cross protection against JEV by immunizingWNV NS1protein? To observe the protection conferred by this vaccination strategy, all mice immunized with recombinant WNV NS1protein were challenged with a lethal dose of JEV (at the timewhen antibody titers peaked). The result showed intracerebrally challenged with JEV,6of20miceimmunized with WNV NS1protein survived, meanwhile all (n=20) of PBS control mice died;intraperitoneally challenged with JEV,18of20mice immunized with WNV NS1protein survived,whereas10of20PBS control mice died.The knowledge and reagents generated in this study have potential applications in differentialdiagnostics and epitope-based marker vaccine and cross protective vaccines development for WNV andviruses of the JE serocomplex.