title: Embryonated eggs as an alternative infection model to investigate Aspergillus fumigatus virulence.
abstract: Infection models are essential tools for studying microbial pathogenesis. Murine models are considered the "gold standard" for studying in vivo infections caused by Aspergillus species, such as A. fumigatus. Recently developed molecular protocols allow rapid construction of high numbers of fungal deletion mutants, and alternative infection models based on cell culture or invertebrates are widely used for screening such mutants to reduce the number of rodents in animal experiments. To bridge the gap between invertebrate models and mice, we have developed an alternative, low-cost, and easy-to-use infection model for Aspergillus species based on embryonated eggs. The outcome of infections in the egg model is dose and age dependent and highly reproducible. We show that the age of the embryos affects the susceptibility to A. fumigatus and that increased resistance coincides with altered chemokine production after infection. The progress of disease in the model can be monitored by using egg survival and histology. Based on pathological analyses, we hypothesize that invasion of embryonic membranes and blood vessels leads to embryonic death. Defined deletion mutant strains previously shown to be fully virulent or partially or strongly attenuated in a mouse model of bronchopulmonary aspergillosis showed comparable degrees of attenuation in the egg model. Addition of nutrients restored the reduced virulence of a mutant lacking a biosynthetic gene, and variations of the infectious route can be used to further analyze the role of distinct genes in our model. Our results suggest that embryonated eggs can be a very useful alternative infection model to study A. fumigatus virulence and pathogenicity.
authors.affiliation: Department for Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany. ilse.jacobsen@hki-jena.de
authors.forename: Ilse D
authors.initials: ID
authors.lastname: Jacobsen
authors.forename: Katharina
authors.initials: K
authors.lastname: Grosse
authors.forename: Silvia
authors.initials: S
authors.lastname: Slesiona
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hube
authors.forename: Angela
authors.initials: A
authors.lastname: Berndt
authors.forename: Matthias
authors.initials: M
authors.lastname: Brock
mesh_terms: D000818:Animals; D001228:Aspergillosis / Q000382:microbiology / Q000473:pathology; D001232:Aspergillus fumigatus / Q000472:pathogenicity*; D018925:Chemokines / Q000276:immunology; D002642:Chick Embryo / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D002645:Chickens; D016207:Cytokines / Q000276:immunology; D004195:Disease Models, Animal; D008099:Liver / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008828:Microbiological Techniques; D012331:RNA, Fungal / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018925:Chemokines; D016207:Cytokines; D012331:RNA, Fungal