Cellular immunity of influenza vaccine lyophilized liposome produced by freeze-thawing

To investigate the cellular immunogenicity of influenza vaccine liposomes dry powder using the film-dispersion and freeze-thawing. Mice were divided into the non-liposomal influenza vaccine group, film-dispersion prepared liposomal influenza vaccine group, freeze-thawing lyophilized influenza vaccine liposome group, positive control group and negative control group(n=5). 6 μg of hemagglutinin of H1N1 subtype per mouse was delivered tracheally to the mice of lyophilized liposomes groups, with the same dose for non-liposomes intraperitoneally delivered groups as the positive control, and PBS intraperotoneal injection group as the negative control. After 28-day of immunization, the proliferationofsplenic lymphocytes was detected by MTT assay; CD4⁺cell and CD8⁺cell were analyzed by flow cytometry. The dry powder of influenza vaccine liposomes prepared by the above two methods, both induce cellular immunity, with no significant difference in the induced on immunogenicity between the prepared products(P< 0. 05). The results showed that freeze-thawing method is feasible in the preparation of vaccine liposomes, leading to the attenuated live vaccine liposome preparation.