Hilbert A K, Fritzsche U, Kissel T
Department of Pharmaceutics and Biopharmacy, Philipps-University, Marburg, Germany.
Vaccine. 1999 Mar 5;17(9-10):1065-73. doi: 10.1016/s0264-410x(98)00323-5.
A monovalent influenza split vaccine was microencapsulated in poly(D,L-lactic-co-glycolic acid) (PLGA) and ABA triblock copolymers using a W/O/W double emulsion technique. To stabilize the antigen, influenza vaccine was also coencapsulated with liposomes. Antigen release from microspheres was determined in vitro using a hemagglutinin-specific ELISA. PLGA-microspheres with liposomes released immunoreactive hemagglutinin in a pulsatile manner, a preferred feature for the development of a single dose vaccine delivery system. Influenza hemagglutinin specific IgG and neutralizing antibody responses were studied in BALB/c mice following subcutaneous injection of different microsphere preparations. PLGA-microspheres elicited a significantly higher primary IgG response compared to nonencapsulated antigen. ABA-microspheres seemed to be less immunogenic than PLGA-microspheres based on the IgG antibody response, however, similar levels of neutralizing antibodies were observed after eight weeks with both polymers. Entrapment of the antigen in liposomes prior to microencapsulation did not further enhance the immune response. The immunopotentating effect of the antigen-loaded microspheres was prominently enhanced when they were given as suspension in fluid antigen, suggesting that free antigen may serve as priming and microencapsulated antigen as booster dose. Eight weeks after a single subcutaneous immunization with PLGA or ABA-microspheres neutralizing antibodies were as high as those obtained after two subcutaneous administrations of fluid vaccine four weeks apart. Microencapsulated influenza antigen may have potential for a single dose vaccine delivery system with adjuvant properties.
采用W/O/W双乳液技术，将单价流感裂解疫苗微囊化于聚（D，L-乳酸-乙醇酸）（PLGA）和ABA三嵌段共聚物中。为稳定抗原，流感疫苗还与脂质体共同包封。使用血凝素特异性ELISA在体外测定微球中的抗原释放。含脂质体的PLGA微球以脉冲方式释放免疫反应性血凝素，这是单剂量疫苗递送系统开发的一个理想特性。皮下注射不同微球制剂后，在BALB/c小鼠中研究了流感血凝素特异性IgG和中和抗体反应。与未包封的抗原相比，PLGA微球引发的初次IgG反应显著更高。基于IgG抗体反应，ABA微球的免疫原性似乎低于PLGA微球，然而，两种聚合物在八周后观察到的中和抗体水平相似。在微囊化之前将抗原包封于脂质体中并未进一步增强免疫反应。当将负载抗原的微球以悬浮液形式与液体抗原一起给药时，其免疫增强作用显著增强，这表明游离抗原可作为启动剂，微囊化抗原可作为加强剂量。用PLGA或ABA微球进行单次皮下免疫八周后，中和抗体水平与相隔四周进行两次皮下注射液体疫苗所获得的水平一样高。微囊化流感抗原可能具有作为具有佐剂特性的单剂量疫苗递送系统的潜力。
