Innate immunity against moulds: Lessons learned from invertebrate models

The emergence over the past two decades of invasive mycoses as a significant problem in immunocompromised patients underscores the importance of deciphering innate immunity against filamentous fungi. However, the complexity and cost of traditionally used mammalian model hosts presents a bottleneck that has limited the rate of advances in this field. In contrast, invertebrate model hosts have several important advantages, including simple immune systems, genetic tractability, and amenity to high-throughput experiments. The application of these models to studies of host-pathogen interactions is contingent on two tenets: (1) host innate defenses are preserved across widely disparate taxa, and (2) similar fungal virulence factors are operative in insects and in mammals. Validation of these principles paved the way for the use of invertebrates as facile models for studying invasive mould infections. These studies have helped shape our understanding of human pattern recognition receptors, phagocytic cell function and antimicrobial proteins, and their roles in host defense against filamentous fungi.