Evaluation of thimerosal removal on immunogenicity of aluminum salts adjuvanted recombinant hepatitis b vaccine

Thimerosal, which is approximately 50% mercury by weight is a preservative widely used in vaccines since the 1930's. It meets the requirements for a preservative as set forth by Pharmacopeia challenge test and has been shown to be effective against a broad spectrum of pathogens. In July 1999, the Public Health Service agencies and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure but, due to the lack of appropriate alternative, it is still extensively used in multiple dose formulations of vaccines such as hepatitis-B in developing countries. In this study the effect of the removal of thimerosal in two formulations of hepatitis B vaccines containing either aluminum hydroxide or aluminum phosphate were evaluated in Balb/c mice. These formulations were administered interperitoneally and the titer of antibody was determined by ELISA technique after 28 days. The geometric mean of antibody titer [GMT], seroconversion and seroprotection rates, ED50 and relative potency of different formulations were determined. The ED50 of thimerosal-free formulations were reduced by more than 35% in both preparations. In addition, GMT of antibody titer, seroconversion and seroprotection indicated significantly higher immunogenicity for thimerosal free formulations for both aluminum phosphate and hydroxide adjuvants

Biological activity analysis of native and recombinant streptokinase using clot lysis and chromogenic substrate assay

Determination of streptokinase activity is usually accomplished through two assay methods: a] Clot lysis, b] Chromogenic substrate assay. In this study the biological activity of two streptokinase products, namely Streptase[registered], which is a native product and Heberkinasa[registered], which is a recombinant product, was determined against the third international reference standard using the two forementioned assay methods. The results indicated that whilst the activity of Streptase[registered] was found to be 101 +/- 4% and 97 +/- 5% of the label claim with Clot lysis and Chromogenic substrate assay respectively, for Heberkinasa[registered] the potency values obtained were 42 +/- 5% and 92.5 +/- 2% of the label claim respectively. To shed some light on the reason for this finding, the n-terminal sequence of the streptokinase molecules present in the two products was determined. The results showed slight differences in the amino acid sequence of the recombinant product in comparison to the native one at the amino terminus. This finding supports those of other workers who found that n-terminal sequence of the streptokinase molecule can have significant effect on the activity of this protein

Comparison of the adjuvanticity of aluminum salts and their combination in hepatitis B recombinant protein vaccine in assessed mice

Several adjuvants have been evaluated for vaccine formulations but aluminum 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, aluminum hydroxide and aluminum phosphate have different adjuvanticity properties. Commercial recombinant protein hepatitis B vaccines containing aluminum hydroxide is facing low induction of immunity in some sections of the vaccinated population. 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. The formulated vaccines were administered 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 [micro g/dose] of different formulations were determined. 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. Aluminum phosphate showed more adjuvanticity than aluminum hydroxide and their combinations in hepatitis B protein vaccine. The use of aluminum phosphate as adjuvant leads to higher immunity which may result in more protective response in vaccinated groups