| Objective: to improve the potency of the currently used influenza split vaccine, which are of relatively low efficiency in high-risk groups. To produce liposome-encapsulated influenza split vaccine(H3N2) and analyzing its humoral and cellular immune response elicited in mice.Method: 1,produce liposome-encapsulated influenza split vaccine and its characterization was studied; 2,then a single dose was administered i.p. to BALB/c mice (5-6 per group) with nonliposomal or liposomal vaccines. Serum antibodies were assayed on weeks 2-13 by the haemagglutination-inhibition(HI) test and ELISA. 3,Using MTT to measure the spleen cell proliferation in vitro; to determine the levels of CD4 and CD8 T-cell and the CD4/CD8 using flow cytometry; to quantify the levels of IL-4 and IFNγin lung homogenates by ELISA kit; 4,the measurement of protective immunity was assessed by the prevention of lung injury from live virus 12weeks post vaccination.Results: the following results were obtained :(1) The efficiency of encapsulation in liposomes was 91.1%.(2)Following immunization with 2μg and 4μg liposome-encapsulated influenza split vaccine, there was a higher, up to 4fold stronger HI titer and ELISA titer than that obtained with non-liposomal HN.(3)The combined liposomal vaccines consisting of encapsulated antigen, but not the nonliposomal vaccine, elicited a higher titer of he spleen cell proliferation and cell subsets like CD4+ and CD4+/CD8+ and the liposome-encapsulated influenza split vaccine triggered cytokine (IL-4 and IFNγ) production.(4)The level of protection following vaccination with the combined liposomal vaccines was 4/6 versus 2/6 in mice immunized with non-liposomal vaccine.Conclusion: our animal experiments show that the liposomal vaccines are superior to the currently used influenza vaccines, increasing the response by 2-4folds in mice, stimulating both TH1 and TH2 responses. Such vaccines may be more potent in high-risk group than the currently used split vaccines. |
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