As the Toll signaling pathway was involved in gram-positive bacteria and fungi infection in insects (Hanson and Lemaitre, 2020), it is suggested that the Toll signaling pathway may play a part in the immune priming of the housefly to C. albicans, and this is consistent with the discovery that Toll signaling pathway was involved in immune priming of D. melanogaster to S. pneumoniae. Here, TLR4 is linked to fungal infectious disease.