Figure 3. Dendritic-cell targeted ALTm enhances humoral and cellular responses against LsALT.

The sequence encoding ALTm was fused to the sequence for a single-chain antibody targeting DEC205 (decALTm) or to a control antibody sequence which was derived from an antibody of the same isotype that does not bind to DCs). All vaccinated mice were also injected with pIL-4, pMIP and pFlt3L. All groups except naïve mice were challenged with live infective L. sigmodontis larvae. The data shown are representative of results obtained at D10 and at D60 p.i. (A) Serum LsALT-specific IgG1 levels were significantly increased in the ALTm and decALTm groups relative to the control plasmids (b vs. [a, ab], P≤0.05, 0.8). (B) LsALT-specific IgG2a concentrations in serum were highly variable. ELISAs were performed with the wild-type recombinant LsALT. (C) Targeting ALTm to dendritic cells did not increase total total serum IgE or (D), eosinophil recruitment to the site of infection but IgE was significantly higher than in naïve controls (C, P = 0.02). Cytokines and cell enumerations were performed on pleural lavage fluid. (E), Parasite survival represented as the proportion of worms found in the pleural cavity of infected mice relative to the infective dose (except naive mice). pEmpty, non-coding plasmid control; ALTm, plasmid encoding the acidic domain-deleted sequence of LsALT; isoALTm, plasmid encoding a non-specific scFv control-ALTm construct; decALTm, plasmid encoding the anti-DEC205 scFv-ALTm construct. Points represent individual mice (N = 5 mice per group).