TLR4 and influenza: Biodegradable synthetic polymeric (PLGA) nanoparticles containing influenza antigens, TLR4, and TLR7 ligands (MPL + R387) have been reported to induce synergistic increases in antigen-specific antibodies and complete protection against lethal influenza virus strains challenge in mice and rhesus macaques [6] (Figure 1D).