A combination of TLR-4 agonist and saponin adjuvants increases antibody diversity and protective efficacy of a recombinant West Nile Virus antigen

Identification and optimization of adjuvant components results in increased neutralizing antibody titers following a single immunization with WN-80E. In order to identify and optimize an SLA containing adjuvant formulation for WN-80E, we have examined the ability of different SLA containing adjuvant formulations to augment neutralizing antibody titers in combination with recombinant WN-80E protein. WN-80E was combined with SLA formulated in Alum (SLA-Alum), in a stable oil-in-water emulsion (SLA-SE), in a liposome (SLA-Lipo) and in liposomes containing QS21 (SLA-LSQ) a. All adjuvants contained 5？μg of SLA. Given elevated titers observed with SLA-LSQ, amounts of QS21 b and SLA c or both in combination (SLA-LSQ) d were optimized in liposomal adjuvants to maximize WNV neutralizing antibody responses, as measured by PRNT. Neutralizing antibodies were assessed 21 days post-immunization (n？=？5/group, a–c, n？=？10/group d). Bars indicate mean PRNT90 titers, dashed lines indicate the limit of detection of the assay. A dose-dependent increase in PRNT titer was observed following immunization with both QS21-Liposome and SLA-Liposome adjuvants. Significant increases relative to those observed in animals immunized with WN-80E alone are indicated (****p？<？0.0001, ***p？<？0.0005, **p？<？0.01, *p？<？0.05, one-way ANOVA). A liposomal adjuvant formulation containing 2？μg of QS21 and varied doses of SLA (SLA-LSQ) showed increased PRNT titers relative to WN-80E alone, and the inclusion of SLA resulted in a statistically significant increase in PRNT titer relative to animals immunized with WN-80E？+？QS21-Liposomes (#p？<？0.01, %p？<？0.05, one-way ANOVA