{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,9]],"date-time":"2026-10-09T13:54:03Z","timestamp":1791554043483,"version":"4.3.4"},"reference-count":63,"publisher":"American Society for Microbiology","issue":"8","license":[{"start":{"date-parts":[[2024,8,14]],"date-time":"2024-08-14T00:00:00Z","timestamp":1723593600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2024,8,14]],"date-time":"2024-08-14T00:00:00Z","timestamp":1723593600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"name":"Deutsche Forschungsgemeinschaft","award":["IA 81\/2-1"],"award-info":[{"award-number":["IA 81\/2-1"]}],"id":[{"id":"https:\/\/ror.org\/018mejw64","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mBio"],"published-print":{"date-parts":[[2024,8,14]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      Facultative endosymbiotic bacteria, such as\n                      <jats:italic toggle=\"yes\">Wolbachia<\/jats:italic>\n                      and\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      species, are commonly found in association with insects and can dramatically alter their host physiology. Many endosymbionts are defensive and protect their hosts against parasites or pathogens. Despite the widespread nature of defensive insect symbioses and their importance for the ecology and evolution of insects, the mechanisms of symbiont-mediated host protection remain poorly characterized. Here, we utilized the fruit fly\n                      <jats:italic toggle=\"yes\">Drosophila melanogaster<\/jats:italic>\n                      and its facultative endosymbiont\n                      <jats:italic toggle=\"yes\">Spiroplasma poulsonii<\/jats:italic>\n                      to characterize the mechanisms underlying symbiont-mediated host protection against bacterial and fungal pathogens. Our results indicate a variable effect of\n                      <jats:italic toggle=\"yes\">S. poulsonii<\/jats:italic>\n                      on infection outcome, with endosymbiont-harboring flies being more resistant to\n                      <jats:italic toggle=\"yes\">Rhyzopus oryzae<\/jats:italic>\n                      ,\n                      <jats:italic toggle=\"yes\">Staphylococcus aureus,<\/jats:italic>\n                      and\n                      <jats:italic toggle=\"yes\">Providencia alcalifaciens<\/jats:italic>\n                      but more sensitive or as sensitive as endosymbiont-free flies to the infections with\n                      <jats:italic toggle=\"yes\">Pseudomonas<\/jats:italic>\n                      species. Further focusing on the protective effect, we identified Transferrin-mediated iron sequestration induced by\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      as being crucial for the defense against\n                      <jats:italic toggle=\"yes\">R. oryzae<\/jats:italic>\n                      and\n                      <jats:italic toggle=\"yes\">P. alcalifaciens<\/jats:italic>\n                      . In the case of\n                      <jats:italic toggle=\"yes\">S. aureus<\/jats:italic>\n                      , enhanced melanization in\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      -harboring flies plays a major role in protection. Both iron sequestration and melanization induced by\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      require the host immune sensor protease Persephone, suggesting a role of proteases secreted by the symbiont in the activation of host defense reactions. Hence, our work reveals a broader defensive range of\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      than previously appreciated and adds nutritional immunity and melanization to the defensive arsenal of symbionts.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>IMPORTANCE<\/jats:title>\n                    <jats:p>\n                      Defensive endosymbiotic bacteria conferring protection to their hosts against parasites and pathogens are widespread in insect populations. However, the mechanisms by which most symbionts confer protection are not fully understood. Here, we studied the mechanisms of protection against bacterial and fungal pathogens mediated by the\n                      <jats:italic toggle=\"yes\">Drosophila melanogaster<\/jats:italic>\n                      endosymbiont\n                      <jats:italic toggle=\"yes\">Spiroplasma poulsonii<\/jats:italic>\n                      . We demonstrate that besides the previously described protection against wasps and nematodes,\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      also confers increased resistance to pathogenic bacteria and fungi. We identified\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      -induced iron sequestration and melanization as key defense mechanisms. Our work broadens the known defense spectrum of\n                      <jats:italic toggle=\"yes\">Spiroplasma<\/jats:italic>\n                      and reveals a previously unappreciated role of melanization and iron sequestration in endosymbiont-mediated host protection. We propose that the mechanisms we have identified here may be of broader significance and could apply to other endosymbionts, particularly to\n                      <jats:italic toggle=\"yes\">Wolbachia<\/jats:italic>\n                      , and potentially explain their protective properties.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1128\/mbio.00936-24","type":"journal-article","created":{"date-parts":[[2024,6,28]],"date-time":"2024-06-28T09:11:57Z","timestamp":1719565917000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":25,"title":["The endosymbiont\n                    <i>Spiroplasma poulsonii<\/i>\n                    increases\n                    <i>Drosophila melanogaster<\/i>\n                    resistance to pathogens by enhancing iron sequestration and melanization"],"prefix":"10.1128","volume":"15","author":[{"given":"Alexandra","family":"Hrdina","sequence":"first","affiliation":[{"name":"Research group Genetics of Host-Microbe Interactions, Max Planck Institute for Infection Biology","place":["Berlin, Germany"]},{"name":"Faculty of Life Sciences, Humboldt-Universit\u00e4t zu Berlin","place":["Berlin, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marina","family":"Serra Canales","sequence":"additional","affiliation":[{"name":"Research group Genetics of Host-Microbe Interactions, Max Planck Institute for Infection Biology","place":["Berlin, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aranzazu","family":"Arias-Rojas","sequence":"additional","affiliation":[{"name":"Research group Genetics of Host-Microbe Interactions, Max Planck Institute for Infection Biology","place":["Berlin, Germany"]},{"name":"Department of Biology, Chemistry, and Pharmacy, Freie Universit\u00e4t Berlin","place":["Berlin, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dagmar","family":"Frahm","sequence":"additional","affiliation":[{"name":"Research group Genetics of Host-Microbe Interactions, Max Planck Institute for Infection Biology","place":["Berlin, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9249-8998","authenticated-orcid":false,"given":"Igor","family":"Iatsenko","sequence":"additional","affiliation":[{"name":"Research group Genetics of Host-Microbe Interactions, Max Planck Institute for Infection Biology","place":["Berlin, 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