Genetic and molecular analysis of nematode-microbe interactions.

Symbiosis, the living together of unlike organisms, such as between microbes and their multicellular eukaryotic hosts, can be categorized as parasitic, commensal or mutualistic. The establishment of symbiosis and the outcome of microbe-host interactions are dictated largely by both microbe- and host-derived factors. Over the last decade, the nematode Caenorhabditis elegans has provided a facile experimental system to study such interactions, with parasitic interactions being the primary focus. The myriad of genetic and molecular tools available has made C. elegans a powerful model system to interrogate the interactions between a host and its pathogens, and has provided a greater understanding of the molecular underpinnings of these interactions, many of which were found to be conserved across other taxa. Commensal and mutualistic interactions between worms and their microbes, although less studied, have the potential to enhance our understanding of genetic and molecular features underlying host-microbe interactions. Here, we highlight new insights obtained in delineating the signalling pathways that function within and between host cells in combating assaults from extracellular and intracellular pathogens. We also discuss potential new insights that could be gained from further studies into commensal and mutualistic relationships between nematodes and microbes.