The effect of Syntex adjuvant formulation (SAF-m) on humoral immunity to the influenza virus in the mouse

Abstract

Syntex adjuvant in its microfluidized form (SAF-m) was equal to or superior to Freund's complete adjuvant in stimulating an enhanced hemagglutination inhibition (HI) antibody response in mice to trivalent influenza virus vaccine (TIV). There was an average 16-fold increase in HI titer for the three components of the vaccine with no significant differences among strains. The increased serum antibodies correlated with an increase in protection against infection. The threonyl-MDP (t-MDP) component of the adjuvant played no role in this activity. The vehicle, in contrast, was so effective that it could be diluted 1:202 (in the presence of t-MDP) and still retain a statistically significant effect. Vaccine and adjuvant could be stored together at 4°C for 2 years without a statistically significant change in potency. Mice were given a priming immunization with TIV, PBS, or adjuvanted TIV (AIV). A year later, the mice were boosted with heterotypic TIV or AIV. The nature of the priming immunization made no difference in the strong antibody response to an AIV boost. However, priming significantly improved the response to TIV with AIV being the best primer. The enhancement in the antibody response to A/Shanghai of the unprimed (PBS) elderly mice caused by AIV (14-fold improvement over TIV) was similar to that in young mice. Female mice had antibody titers which overall were 2.6-fold higher than those of males ( P<0.0001) for AIV and TIV.