The universal influenza vaccine M2e-HBc administered intranasally in combination with the adjuvant CTA1-DD provides complete protection

Mucosal vaccination requires effective and safe adjuvants. We have evaluated the non-toxic adjuvant CTA1-DD for mucosal vaccination against influenza. CTA1-DD contain, the enzymatically active CTA1 subunit of cholera toxin (CT) genetically fused to a gene encoding a dimer of the D-fragment from Staphylococcus aureus protein A. CTA1-DD only binds to Ig-receptor carrying cells of the immune system. Nasal administration of the universal influenza vaccine M2e-HBc in combination with CTA1-DD completely protected mice from a potentially lethal infection and significantly reduced morbidity. Sera of mice immunized with M2e-HBc + CTA1-DD revealed IgG subclass profiles consistent with an enhanced Th1-type immunity. When the vaccine was administered intraperitoneally, the adjuvant improved the M2e antibody titer in circulation, but did not significantly reduce the morbidity. (c) 2005 Elsevier Ltd. All rights reserved.