Cytotoxicity, intracellular transit and immune response induced by two subcutaneous (sc) administrations (days 0 and 21) with BSA entrapped in ARC made of TPL either form BM (ARC-BM) and from GC (ARC-GC) at 2% w/w (BSA/lipids), to C3H/HeN mice (25 μg BSA, 1.3 mg of archaeal lipids per mouse) and boosted on day 180 with 25 μg of bare BSA, were determined.
The possibility that the tyvelose component itself may have a host- or parasite-protective role in the intestine was tested by following the outcome of challenge infections in mice primed and boosted with tyvelose-BSA, or in mice primed with tyvelose-BSA before boosting with larval antigen.
At 1∶20 dilution, sera from mice #2 and #25 exhibited 57% and 55% inhibition, respectively; while at the same dilution, immune sera from mice primed and boosted with H5N1 VLP exhibited 50 to 72% inhibition.
An enhanced and comparable antibody response with varied IgG isotype combinations were noticed in the mice primed and boosted with rOP in adjuvants.
Therefore, serum collected from mice primed and boosted with the recombinant proteins were tested for HAI titers.
We found that mice primed and boosted with 3 µg of trimeric sHA in the absence of adjuvants had significantly higher IgG and HAI titers than mice that received the unmodified sHA.
In contrast, all mice primed and boosted with VLP expressing H5HA and N1NA exhibited decent neutralizing antibody titers against H5N1 (Figure 3c), but none of them had measurable neutralization titers against H1N1 and H3N2 (Figure 3a and 3b).
All mice primed and boosted with seasonal influenza vaccine exhibited high neutralizing antibody titers against H1N1 (Figure 3a) and H3N2 (Figure 3b), but relatively lower neutralizing antibody titers against H5N1 with exception of serum samples from mice #2 and #25 (Figure 3c).
We determined the effect of this stabilization on the immunogenicity of the protein vaccine and its ability to induce a protective immune response to challenge with homologous virus in mice primed and boosted with a low dose of vaccine without adjuvants.
The mean frequency observed with iPEM capsules (3.1%) represented a 4.5-fold enhancement over the level (0.7%) observed in mice treated and boosted with the admixed formulations of antigen and polyIC.
