Flu Vaccine Plus GLA-SE Figure 1. GLA-SE enhances HI titers to the A/H3N2 vaccine component and antigenically drifted A/H3N2 influenza strains. Balb/c mice were immunized with Fluzone (2006–2007) either alone ( - ), or formulated with emulsion (SE), or glucopyranosyl-lipid-adjuvant (GLA-SE). (A) Serum HI titers one week after the prime and boost (N = 7 mice/group). Shown are the individual mouse HI titers (diamonds) and the geometric mean titer (GMT) (indicated by the horizontal bars6the 95% CI) against the vaccine strain (Wis/05) and the antigenically drifted H3N2 strains. The assay detection limit was set at #10. Statistical significance between groups was determined and compared to Fluzone (*p,0.05) or Fluzone+SE (**p,0.05). (B) The fold-increase in mean HI titer over that seen with Fluzone is shown for Fluzone+SE or Fluzone+GLA-SE one week after the prime and boost immunizations. doi:10.1371/journal.pone.0013677.g001 (Table S2). Even after boosting, only 1 of 3 NHP in the Fluzone- alone group achieved titers of = 40 against the A/H1N1 and B/ Malaysia components; these results differ from the stronger responses detected against the A/H3N2 component (Table S2). In contrast to the observations made in mice, the serum HI Ab titers of NHP following one (day 30) or two immunizations (day 58) with Fluzone+SE were not significantly different compared to the group administered the Fluzone vaccine alone (Figure 3). Neverthe- PLoS ONE | www.plosone.org 3 October 2010 | Volume 5 | Issue 10 | e13677