| Objective: to improve the potency of the currently used influenzasplit vaccine, which are of relatively low efficiency in high-riskgroups. To produce liposome-encapsulated influenza splitvaccine(H3N2) and analyzing its humoral and cellular immuneresponse elicited in mice.Method: 1,produce liposome-encapsulated influenza split vaccineand its characterization was studied;2, then a single dose wasadministered i.p. to BALB/c mice (5-6 per group) with nonliposomalor liposomal vaccines. Serum antibodies were assayed on weeks 2-13by the haemagglutination-inhibition(HI) test and ELISA. 3,UsingMTT to measure the spleen cell proliferation in vitro;to determinethe levels of CD4 and CD8 T-cell and the CD4/CD8 using flowcytometry;to quantify the levels of IL-4 and IFNγ in lunghomogenates by ELISA kit;4,the measurement of protectiveimmunity was assessed by the prevention of lung injury from livevirus 12weeks post vaccination.Results: the following results were obtained :(1) The efficiencyof encapsulation in liposomes was 91.1%.(2)Following immunizationwith 2μg and 4μg liposome-encapsulated influenza split vaccine,there was a higher, up to 4fold stronger HI titer and ELISA titer thanthat obtained with non-liposomal HN.(3)The combined liposomalvaccines consisting of encapsulated antigen, but not the nonliposomalvaccine, elicited a higher titer of he spleen cell proliferation and cellsubsets like CD4+ and CD4+/CD8+ and the liposome-encapsulatedinfluenza split vaccine triggered cytokine (IL-4 and IFNγ)production.(4)The level of protection following vaccination with thecombined liposomal vaccines was 4/6 versus 2/6 in mice immunizedwith non-liposomal vaccine.Conclusion: our animal experiments show that the liposomalvaccines are superior to the currently used influenza vaccines,increasing the response by 2-4folds in mice, stimulating both TH1and TH2 responses. Such vaccines may be more potent in high-riskgroup than the currently used split vaccines.
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