title: Infections by Pasteuria do not protect its natural host Daphnia magna from subsequent infections.
abstract: The existence of immunological memory in invertebrates remains a contentious topic. Exposure of Daphnia magna crustaceans to a noninfectious dose of the bacterium Pasteuria ramosa has been reported to reduce the chance of future infection upon exposure to higher doses. Using clonal hosts and parasites, we tested whether initial exposure of the host to the parasite (priming), followed by clearing of the parasite with antibiotic, protects the host from a second exposure (challenge). Our experiments included three treatments: priming and challenge with the same or with a different parasite clone, or no priming. Two independent experiments showed that both the likelihood of infection and the degree of parasite proliferation did not differ between treatments, supporting the conclusion that there is no immunological memory in this system. We discuss the possibility that previous discordant reports could result from immune or stress responses that did not fade following initial priming.
authors.affiliation: University of Basel, Zoological Institute, Vesalgasse 1, Basel, Switzerland. Electronic address: david.duneau@univ-tlse3.fr.
authors.forename: David
authors.initials: D
authors.lastname: Duneau
authors.affiliation: University of Basel, Zoological Institute, Vesalgasse 1, Basel, Switzerland.
authors.forename: Dieter
authors.initials: D
authors.lastname: Ebert
authors.affiliation: University of Basel, Zoological Institute, Vesalgasse 1, Basel, Switzerland.
authors.forename: Louis
authors.initials: L
authors.lastname: Du Pasquier
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003621:Daphnia / Q000276:immunology*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000276:immunology*; D054884:Host-Pathogen Interactions; D007113:Immunity, Innate; D007156:Immunologic Memory; D058676:Pasteuria / Q000276:immunology*; D012008:Recurrence; D014611:Vaccination
chemical_list: D000900:Anti-Bacterial Agents
keywords: Daphnia; Host–parasite interaction; Immune priming; Invertebrate; Pasteuria