DEVELOPMENT OF DRIED LIPOSOME AS EFFECTIVE IMMUNO-ADJUVANT FOR HEPATITIS-B SURFACE-ANTIGEN

Dried liposomes containing recombinant hepatitis B surface antigen (HBsAg) were developed to enhance the immunogenicity of HBsAg and to retain the stability of liposomal HBsAg during storage. Vesicles containing HBsAg were prepared by extruding the dehydration-rehydration vesicles with entrapped HBsAg through 400 nm polycarbonate filter. The sized liposomes were lyophilized in the presence of trehalose (4 g/g lipid) as a cryopreservative. Dried liposomes were rehydrated in distilled water with brief vortexing prior to use. When rehydrating the dried liposomes after 1 year of storage at 4 degrees C, the vesicles showed a size distribution similar to that obtained before lyophilization, and retained about 70% of HBsAg immunogenicity. Dried liposomes containing HBsAg showed significantly earlier sere-conversion (p < 0.05) and higher titre compared to the free HBsAg and the mixture of KBsAg and aluminum phosphate. Taken together, these results suggest that the dried liposomes, with high stability and enhanced immunogenicity, can be further developed as potential immuno-adjuvants for HBsAg.