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

Dried liposomes containing recombinant hepatitis B surface antigen (HB sAg) were developed to enhance the immunogenicity of HBsAg and to reta in the stability of liposomal HBsAg during storage. Vesicles containin g HBsAg were prepared by extruding the dehydration-rehydration vesicle s 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 wa ter with brief vortexing prior to use. When rehydrating the dried lipo somes after 1 year of storage at 4 degrees C, the vesicles showed a si ze distribution similar to that obtained before lyophilization, and re tained about 70% of HBsAg immunogenicity. Dried liposomes containing H BsAg showed significantly earlier sere-conversion (p < 0.05) and highe r titre compared to the free HBsAg and the mixture of KBsAg and alumin um phosphate. Taken together, these results suggest that the dried lip osomes, with high stability and enhanced immunogenicity, can be furthe r developed as potential immuno-adjuvants for HBsAg.