Ohta, et al. 82 identified a novel bioactive immune-activating polysaccharide composed of nine monosaccharides in the pupae of the melon fly belonging to Diptera, which induced proinflammatory cytokines and interferon β (IFNβ) in mouse against various pathogenic microorganisms and viral infections through the TLR4 signalling pathway. Here, TLR4 is linked to viral infectious disease.