Similarly to , Is a Positive Regulator of the Humoral Immune Response in the Silkworm, .

Toll receptors play important roles in the development and innate immunity of insects. Previously, we reported the immunological function of in silkworm, , larvae. In this study, we focused on the role of as a regulator in the Toll signaling pathway. The expressions of most signaling genes in the Toll pathway, as well as immune effectors, were reduced after the RNAi of . Coincidentally, hemolymph from -silenced larvae exhibited decreased antibacterial activity in the growth of , demonstrated either by growth curve or inhibitory zone experiments. The oral administration of heat-inactivated and following the RNAi of up-regulated the expression of most signaling genes in the Toll pathway and downstream immune effectors. The above results indicate that is positively involved in the Toll signaling pathway. As a positive regulator, is shown to be activated preferentially against and, in turn, positively modulates the humoral immune response in antibacterial activity.