Induction Of Mucosal Immune Responses And Protection Of Cattle Against Contact Challenge By Intranasal Delivery With FMDV Antigen Mediated By Nanoparticles

Two kinds of nanoparticles vaccine of Type A foot-and-mouth disease (FMD) were designed on thebasis of the earlier research of our laboratory.1， Chi-Tre-Inactivated vaccine： enrichmentand purification of FMD inactivated antigen, detect the contents of146s by ultravioletspectrophotometer，then freezing and drying at ultra-low temperature blended with chitosan, trehalose,then grinding of nanometer level;2,Chi-PLGA-DNA vaccine: build the eukaryotic expression vectorpcDNA3.1/P12A-3c of type A, then freezing and drying at ultra-low temperature blended withchitosan、PLGA after the identification of its immunogenicity，then grinding at nanometer level.Cattle immunized by intranasal though mucosa and establish negative control and inactivatedintramuscular immunization, The level of SIgA and IgA were detected though ELISA method; The Tlymphocyte proliferation activity were detected though CFSE method; The level of CD4+and CD8+were detected though Flow cytometry.Direct contact challenge, observing the symptoms of each experimental group and statistics theprotection, RNA copies was detected by Real-time fluorescence quantitative PCR, compare the RNAcopies in nasal and OP liquid after direct contact challenge between the bovine that appear thesymptoms early, delayed and no clinical symptoms.Results: the SIgA can be detected on the4th day after mucosal immune, and higher on the10th day（dpi）,the group of Chi-PLGA-DNA has the highest level of sIgA; the group of Chi-PLGA-DNAshowed a good lymphocytes proliferation activities; both of the two vaccine can cause the content ofCD4+, CD8+increased; the RNA copies of the protected bovine is negative, the RNA copies of thedelayed bovines is relatively low compared with negative control, RNA content is relatively low in bodyfluids.Conclusion: Both of the Chi-Tre-Inactivated vaccine and Chi-PLGA-DNA vaccine not only caninduce local nasal mucosal immune response, but also can induce the systemic humoral immuneresponses and cell immune response; vaccine of Chi-PLGA-DNA is more effectively than vaccine ofChi-Tre-Inactivated vaccine; In conclusion, although intranasal delivery with FMDV antigen mediatedby nanoparticles could not provide complete clinical or virological protection, it reduced the severity ofthe disease, virus excretion and delayed clinical symptoms.