Insect anti-viral immunity: roles of prostaglandins and other eicosanoids

Authors: Stanley, David; ZHANG, LEI - Chinese Academy Of Agricultural Sciences; KIM, YONGGYUN - Andong National University

Submitted to: Invertebrate Survival Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2015
Publication Date: 5/22/2015
Citation: Stanley, D.W., Zhang, L., Kim, Y. 2015. Insect anti-viral immunity: roles of prostaglandins and other eicosanoids. Invertebrate Survival Journal. 12:166-169.

Interpretive Summary: Application of classical insecticides has introduced severe problems in agricultural sustainability. The concept of biological control of insects is a potentially powerful alternative to classical insecticides. Biological control is based on the idea that direct application of insect-specific pathogens and parasites can reduce pest insect populations and the economic damage due to pest insects. The problem, however, is the efficiency of these organisms in biological control programs is limited by insect immune defense reactions to infection. One approach to improving the efficiency of biocontrol agents would be to somehow disable insect immune reactions to viral, bacterial, fungal and parasitic infections. With this goal, we are investigating how insect immune reactions to infection are signaled. In this paper we report on identification of biological signals responsible for stimulating insect defenses to infection. This new research will be directly useful to scientists who are working to improve the efficacy of biological control methods. The ensuing improved biological control methods will benefit a wide range of agricultural producers and users by supporting the long-term sustainability of agriculture.

Technical Abstract: Insect/microbe relationships are very complex, with an array of signaling systems acting in surveillance, detection and responses to the presence of microbes. We report that prostaglandins (PGs) are responsible for essential signaling in activating and coordinating insect innate immune reactions to infections, including viral infections. Insect hemocytes make up the immediate defense against microbial infections. Hemocytic actions include phagocytosis, encapsulation and nodulation. Phagocytosis and nodulation is responsible for clearing the majority of infecting microbes from hemolymph circulation. PGs signal phagocytosis, microaggregation and nodulation reactions to infection. Insects express several mechanisms to protect themselves from viral infections. We investigated the idea that PG also mediate insect anti-viral immune functions. Treating gypsy moth larvae, Lymantria dispar, with various inhibitors of PG biosynthesis increased larval susceptibility to its nucleopolyhedrovirus, LdMNPV, from which it was inferred eicosanoids act in insect responses to baculovirus infection. Insects also clear some viral infections from circulation via nodule formation. We show that PGs mediate nodulation reactions to viral infection in pest insect species. PGs and other eicosanoids are central operators in insect immune signaling and in cross-talk with other signal systems, including an insect cytokine. The identification of several PG-mediated immune reactions creates a sound basis for continued fundamental research into these systems, with the expectation of practical applied outcomes