Immune effect of electric charge modified influenza vaccine liposomes / 中国生物制品学杂志

ABSTRACT

@#Objective To explore the physical and chemical properties of electric charge modified liposomes and the immune enhancement effect as influenza vaccine adjuvants.Methods Four kinds of electric charge-modified liposomes were prepared with soybean lecithin,cholesterol,N-1-(2,3-dioleyloxy) propyl-N,N,N-trimethyllam-moniumchloride(DOTAP)and 1,2-dioleoyl-sn-glycero-3-phosphocholine(DOPC)(DOTAP and DOPC mass ratio 1:4,2:3,3:2 and 4:1).The tetravalent influenza vaccine was mixed with the four liposomes according to the volume fraction of 1.4:1.0,which was prepared into cationic modified influenza vaccine liposome freeze-dried powder by freeze-thaw freeze-drying method.The liposome freeze-dried powder was redissolved with PBS,the particle size and Zeta potential were measured by laserparticle size analyzer,and the encapsulation efficiency of liposome was measured by Lowry method.231 female KM mice were randomly divided into negative control group(PBS),positive control group(tetravalent vaccine bulk),cationic liposome group(four electric charge modified influenza vaccine liposomes) and neutral liposome group(non-electric charge modified influenza vaccine liposomes),which were injected intraperitoneally at 7,14 and 28 d,0.2 mL per mouse.The cellular immune effect was evaluated by MTT assay and T lymphatic surface labeling,and the humoral immune effect was evaluated by hemagglutinin inhibition(HI) at 3,7,14,28,42 and 56 d of immunization.Results When the mass ratio of DOTAP to DOPC was 4:1,the particle size and Zeta potential of cationic modified liposomes reached the maximum,which were 529.65 nm and 12.05 mV respectively,and the encapsulation efficiency was also high,which was 81.82%.Stimulus index(SI) and CD4~+/CD8~+value of spleen cells of mice in the four cationic liposome groups were significantly higher than those in the negative control group(F=4.651～25.866,each P<0.05),among which,the two indexes in 4:1 cationic liposome group were higher than those in the other three groups;mice in this group produced early humoral immune effect 3 d after immunization,and the antibody titer reached the highest 42 d after immunization and maintained a high level during the whole immunization cycle.Conclusion Cationic liposomes with different electric charge modifications improved the immune effect of influenza vaccine,the immune enhancement effect was the best and the immune effect lasted the longest when the mass ratio of DOTAP to DOPC was 4:1.