5 - Evidence for Specificity and Memory in the Insect Innate Immune Response

Abstract

It has been generally assumed that due to the short lifespan of insects, the ability to mount a specific immune response would not confer a selective advantage. Innate immunity is characterized as lacking memory and specificity. However, experimental evidence suggests that the insect immune response does not respond identically to repeat challenges and can exhibit a high degree of specificity. Specificity refers to the fact that the enhanced response is only triggered by the same elicitor encountered during the first exposure and is directed only against that elicitor. Research to date has provided much insight to the molecular mechanisms involved in microbial recognition and signaling. This chapter attempts to exhibit evidence for specificity and memory in insect immune response. Recent evidence demonstrates that invertebrates are able to modulate their innate immune response after repeated challenges. These “adaptive” innate immune responses have been divided into two different classes. The first class involves two categories of nonspecific memory: prolonged nonspecific activation and transgenerational memory. The second class includes transplantation and bacterial priming experiments that demonstrate that the insect innate immune response can exhibit both memory and greater specificity than would be anticipated. In light of the functional experiments demonstrating adaptive aspects of innate immunity, further studies regarding the effectors of the immune response can be anticipated. Adaptive immunity is usually thought to occur within a single individual. However, a survey of insect immunity across species demonstrates the existence of transgenerational, behavioral, and social aspects of the immune response.