Comparison of the Adjuvanticity of Aluminum Salts and Their Combination in Hepatitis B Recombinant Protein Vaccine Assessed in Mice

Background: Several adjuvants have been evaluated for vaccine formulations but alu-minum salts will continue to be used for many years due to their safety, low cost and adjuvanticity with different antigens. Two commonly used aluminum adjuvants, alumi-num hydroxide and aluminum phosphate have different adjuvanticity properties. Com-mercial recombinant protein hepatitis B vaccines containing aluminum hydroxide is fac-ing low induction of immunity in some sections of the vaccinated population. Objec-tive: In this study, to follow the current global efforts in finding more potent hepatitis B vaccine formulations, adjuvanticity of aluminum phosphate, aluminum hydroxide and their combinations has been evaluated. Methods: The formulated vaccines were admin-istered intra-peritoneally (i.p.) to BALB/c mice and the titer of antibody was determined after 28 days using ELISA technique. The geometric mean of antibody titer (GMT, mIU/ml), seroconversion and seroprotection rates, ED50 (ng) and relative potency (μg/dose) of different formulations were determined. Results: GMT of antibody titer, seroconversion and seroprotection rates showed significantly higher adjuvanticity for aluminum phosphate than other formulations. The ED50 of aluminum phosphate was approximately two fold less than other formulations. Conclusion: Aluminum phosphate showed more adjuvanticity than aluminum hydroxide and their combinations in hepati-tis B protein vaccine. The use of aluminum phosphate as adjuvant leads to higher im-munity which may result in more protective response in vaccinated groups.