The Preparation And Mucosal Immunity Study Of Influenza Vaccine Lyophilized Liposome

Influenza virus mainly infects the epithelial cells of respiratory tract, which is the first site of influenza virus entrance. Therefore, the development of respiratory vaccine and the research on mucosal immunity against influenza virus infection appear to be particularly important.Liposome is not only a good carrier of respiratory tract delivery drug, but also an ideal vaccine adjuvant. By administrated respiratorily, liposome vaccine mimics the natural pathway of influenza virus infection. Respiratory tract delivery of liposome vaccine can not only enhance humoral and cellular immunity, but also the mucosal immune responseBased on the film-dispersion method which we did previously, we studied the freeze-thawing lyophilized method in liposome preparation and compared the diameter distribution, encapsulation efficiency and stability of influenza vaccine liposomes prepared by two methods. The mean size of freeze-thawing lyophilized liposomes is4.27μm, particles between1.0-7.0μm in diameter accounts for97.12%, which indicates uniform particle size distribution. The encapsulation efficiency of lyophilized liposomes is79.17%. The physical stability of freeze-thawing lyophilized liposomes at different temperatures (4℃,25±2℃,40±2℃) is similar with that from the film-dispersion lyophilized liposomes. The encapsulation efficiency of lyophilized liposomes by two methods has no significant change during storage at4℃for180days, with less than10%leakage rate. Furthermore, the whole process of freeze-thawing lyophilized liposomes preparation is under mild condition, which could meets the special requirements of live attenuated vaccine liposomes preparation.We have investigated the humoral and cellular immune effects of film-dispersion lyophilized liposomes. The respiratory tract mucosal immunity effect of the influenza (H3N2) vaccine lyophilized liposomes was evaluated in this study. The indirect ELISA method was used to measure the serum IgG and respiratory mucosal slgA levels of immunitied mice. The respiratory slgA level of the influenza vaccine lyophilized liposome group was higher than that of the intraperitoneal group (P<0.05). The slgA level of upper respiratory tract (nasopharynx) was significantly higher than that of the lower respiratory tract (lung)(P<0.01). The influenza vaccine lyophilized liposome could induce effectively respiratory mucosal immunity.