{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T15:00:25Z","timestamp":1790780425750,"version":"4.1.0"},"reference-count":57,"publisher":"American Society for Microbiology","issue":"7","license":[{"start":{"date-parts":[[2008,4,1]],"date-time":"2008-04-01T00:00:00Z","timestamp":1207008000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Appl Environ Microbiol"],"published-print":{"date-parts":[[2008,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            The freshwater ciliate\n            <jats:italic>Tetrahymena<\/jats:italic>\n            sp. efficiently ingested, but poorly digested, virulent strains of the gram-negative intracellular pathogen\n            <jats:italic>Legionella pneumophila<\/jats:italic>\n            . Ciliates expelled live legionellae packaged in free spherical pellets. The ingested legionellae showed no ultrastructural indicators of cell division either within intracellular food vacuoles or in the expelled pellets, while the number of CFU consistently decreased as a function of time postinoculation, suggesting a lack of\n            <jats:italic>L. pneumophila<\/jats:italic>\n            replication inside\n            <jats:italic>Tetrahymena<\/jats:italic>\n            . Pulse-chase feeding experiments with fluorescent\n            <jats:italic>L. pneumophila<\/jats:italic>\n            and\n            <jats:italic>Escherichia coli<\/jats:italic>\n            indicated that actively feeding ciliates maintain a rapid and steady turnover of food vacuoles, so that the intravacuolar residence of the ingested bacteria was as short as 1 to 2 h.\n            <jats:italic>L. pneumophila<\/jats:italic>\n            mutants with a defective Dot\/Icm virulence system were efficiently digested by\n            <jats:italic>Tetrahymena<\/jats:italic>\n            sp. In contrast to pellets of virulent\n            <jats:italic>L. pneumophila<\/jats:italic>\n            , the pellets produced by ciliates feeding on\n            <jats:italic>dot<\/jats:italic>\n            mutants contained very few bacterial cells but abundant membrane whorls. The whorls became labeled with a specific antibody against\n            <jats:italic>L. pneumophila<\/jats:italic>\n            OmpS, indicating that they were outer membrane remnants of digested legionellae. Ciliates that fed on genetically complemented\n            <jats:italic>dot<\/jats:italic>\n            mutants produced numerous pellets containing live legionellae, establishing the importance of the Dot\/Icm system to resist digestion. We thus concluded that production of pellets containing live virulent\n            <jats:italic>L. pneumophila<\/jats:italic>\n            depends on bacterial survival (mediated by the Dot\/Icm system) and occurs in the absence of bacterial replication. Pellets of virulent\n            <jats:italic>L. pneumophila<\/jats:italic>\n            may contribute to the transmission of Legionnaires\u2019 disease, an issue currently under investigation.\n          <\/jats:p>","DOI":"10.1128\/aem.01214-07","type":"journal-article","created":{"date-parts":[[2008,2,2]],"date-time":"2008-02-02T02:07:33Z","timestamp":1201918053000},"page":"2187-2199","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":93,"title":["Packaging of Live\n            <i>Legionella pneumophila<\/i>\n            into Pellets Expelled by\n            <i>Tetrahymena<\/i>\n            spp. Does Not Require Bacterial Replication and Depends on a Dot\/Icm-Mediated Survival Mechanism"],"prefix":"10.1128","volume":"74","author":[{"given":"Sharon G.","family":"Berk","sequence":"first","affiliation":[{"name":"Center for the Management, Utilization and Protection of Water Resources, Tennessee Technological University, Cookeville, Tennessee"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gary","family":"Faulkner","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elizabeth","family":"Gardun\u0303o","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mark C.","family":"Joy","sequence":"additional","affiliation":[{"name":"Center for the Management, Utilization and Protection of Water Resources, Tennessee Technological University, Cookeville, Tennessee"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marco A.","family":"Ortiz-Jimenez","sequence":"additional","affiliation":[{"name":"Instituto de Investigaciones Biome\u0301dicas, Universidad Auto\u0301noma de Me\u0301xico, Mexico City, D.F., Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rafael A.","family":"Gardun\u0303o","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada"},{"name":"Department of Medicine-Division of Infectious Diseases, Dalhousie University, Halifax, Nova Scotia, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","first-page":"10","year":"1992","unstructured":"American Public Health Association, American Water Works Association, and Water Environment Federation. 1992. 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