Analysis of the immune-related transcriptome of a lophotrochozoan model, the marine annelid Platynereis dumerilii

Background: The marine annelid Platynereis dumerilii (Polychaeta, Nereididae) has been recognized as a slow-evolving lophotrochozoan that attracts increasing attention as a valuable model for evolutionary and developmental research. Here, we analyzed its immune-related transcriptome. For targeted identification of immune-induced genes we injected bacterial lipopolysaccharide, a commonly used elicitor of innate immune responses, and applied the suppression subtractive hybridization technique that selectively amplifies cDNAs of differentially expressed genes. Results: Sequence analysis of 288 cDNAs revealed induced expression of numerous genes whose potential homologues from other animals mediate recognition of infection (e.g. complement receptor CD35), signaling (e.g. myc and SOCS), or act as effector molecules like ferritins and the bactericidal permeability-increasing protein. Interestingly, phylogenetic analyses implicate that immune-related genes identified in P. dumerilii are more related to counterparts from Deuterostomia than are those from Ecdysozoa, similarly as recently described for opsin and intron-rich genes. Conclusion: Obtained results may allow for a better understanding of Platynereis immunity and support the view that P. dumerilii represents a suitable model for analyzing immune responses of Lophotrochozoa.