Meeting Abstract
The complement system is an innate immune pathway that in vertebrates, involves a series of proteolytic cleavage events that initiate phagocytosis and destruction of foreign cells. Recent studies demonstrate a conserved role for this pathway in invertebrate immunity, but little work has focused on the role of complement molecules in cnidarians. Complement proteins, including C3, Factor B, and MASP have recently been characterized in the anemone Aiptasia making it a good model to study the role of complement in immunity and to investigate the interactions between immunity and symbiosis. In this study, the expression of two Factor B (Bf) and one MASP gene in response to challenge with the coral pathogen Serratia marcescens was measured using quantitative PCR (qPCR). The data indicate challenge with S. marcescens resulted in changes in expression that are dependent on both density of bacteria and symbiotic state. Specifically, Ap_Bf-1 and Ap_MASP were most responsive in symbiotic animals to a low concentration of bacteria, but in contrast, Ap_Bf-2b expression shows a more complex response, and its role in the response against pathogens is unclear. Overall, this study provides information on the role of the complement system in the immune response of a basal metazoan.
