Immunological Effect of Entrapped Subunit Influenza Vaccine by Liposomes

Objective To elevate the immunological effect of subunit influenza vaccine in infants and aged people （over 60） using liposomal adjuvant in the context of its relatively low immunity and to investigate the relation between vaccine antigens and liposomal characteristics. Methods Several formulations of liposomal subunit influenza vaccine were prepared. Their relevant characteristics were investigated to optimize the preparation method. Antisera obtained from immunizinged mice were used to evaluate the antibody titers of various samples by HI and EL1SA. Results Liposomal trivalent influenza vaccine prepared by film evaporation in combinedation with freeze-drying significantly increased its immunological effect in SPF Balb/e mice. Liposomal vaccine stimulated the antibody titer of H3N2, H1N1, and B much stronger than conventional influenza vaccine. As a result, liposomal vaccine （mean size： 4.5-5.5 pm, entrapment efficiency： 30%-40%） significantly increased the immunological effect of subunit influenza vaccine. Conclusion The immune effect of liposomal vaccine depends on different antigens, and enhanced immunity is not positively correlated with the mean size of liposome or its entrapped efficiency.