{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T16:37:10Z","timestamp":1790095030443,"version":"4.0.1"},"reference-count":58,"publisher":"American Society for Microbiology","issue":"1","license":[{"start":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T00:00:00Z","timestamp":1768348800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T00:00:00Z","timestamp":1768348800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/100000060","name":"National Institute of Allergy and Infectious Diseases","doi-asserted-by":"publisher","award":["R01AI141877"],"award-info":[{"award-number":["R01AI141877"]}],"id":[{"id":"10.13039\/100000060","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mBio"],"published-print":{"date-parts":[[2026,1,14]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      <jats:italic toggle=\"yes\">Mycoplasma pneumoniae<\/jats:italic>\n                      (\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      ) causes both pulmonary and extrapulmonary infections in humans, and its virulence is largely attributed to the community-acquired respiratory distress syndrome (CARDS) toxin. CARDS toxin is transiently expressed during\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      growth in the serum-rich SP4 medium, detected predominantly in the cytoplasm, with none secreted into the medium. Here, we show that CARDS toxin synthesis has increased at least fivefold during\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      growth in serum-free minimal media, with approximately 40% of the toxin being released into the extracellular environment. In infected human alveolar epithelial cells, the toxin is visualized both in association with\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      and in free form around the perinuclear region, confirming its secretion. Using density gradient centrifugation, transmission electron microscopy, and immunoblotting, we demonstrate that\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      secretes extracellular vesicles enriched with CARDS toxin. Approximately 35% of the secreted toxin is associated with vesicles, while the remainder exists in a free-soluble form. The vesicle-bound toxin shows increased resistance to proteolytic degradation compared to the free-soluble toxin. Both forms of the purified toxin are biologically active and induce varying degrees of cytotoxicity in human epithelial cells based on their distinct trafficking patterns, which highlights their distinct roles in host-cell interactions. Together, these findings reveal a dual mode of CARDS toxin secretion as a key feature of\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      pathogenicity, providing a significant benefit in toxin delivery and thereby enhancing virulence, expanding the scope of infection.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>IMPORTANCE<\/jats:title>\n                    <jats:p>\n                      <jats:italic toggle=\"yes\">Mycoplasma pneumoniae<\/jats:italic>\n                      (\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      ) is a significant human respiratory pathogen whose systemic effects are largely caused by the CARDS toxin. Our study provides new insights into the secretion and delivery of CARDS toxin. We demonstrate that\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      highly expresses and selectively releases CARDS toxin when grown in serum-free minimal media and during interaction with host cells. Importantly,\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      utilizes two distinct pathways to secrete CARDS toxin: extracellular vesicles (EVs) and a non-EV-mediated route. Compared to the free-soluble toxin, the vesicle-associated CARDS toxin resists proteolytic degradation, which likely enhances its ability to act on distant sites. Both forms of toxin exhibit varying degrees of cytotoxicity on human epithelial cells, highlighting their distinct roles in host-cell interactions. These findings reveal that\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      uses multiple strategies to propagate its virulence factors effectively. Understanding these delivery mechanisms provides potential new targets for developing therapeutic interventions to counteract\n                      <jats:italic toggle=\"yes\">Mp<\/jats:italic>\n                      pathogenesis, particularly those mediated by CARDS toxin.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1128\/mbio.02640-25","type":"journal-article","created":{"date-parts":[[2025,11,28]],"date-time":"2025-11-28T13:58:46Z","timestamp":1764338326000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":2,"title":["Dual mode of delivery of\n                    <i>Mycoplasma pneumoniae<\/i>\n                    CARDS toxin determines the toxin trafficking pathway and cytotoxicity in host cells"],"prefix":"10.1128","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0507-1970","authenticated-orcid":false,"given":"K.","family":"Sreenath","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02f6dcw23","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, Immunology and Molecular Genetics, The University of Texas at San Antonio","place":["San Antonio, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Linbo","family":"Li","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02f6dcw23","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, Immunology and Molecular Genetics, The University of Texas at San Antonio","place":["San Antonio, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Danielle","family":"Molotsky","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02f6dcw23","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, Immunology and Molecular Genetics, The University of Texas at San Antonio","place":["San Antonio, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jason","family":"Ayo","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02f6dcw23","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, Immunology and Molecular Genetics, The University of Texas at San Antonio","place":["San Antonio, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joel B.","family":"Baseman","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02f6dcw23","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, Immunology and Molecular Genetics, The University of Texas at San Antonio","place":["San Antonio, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4590-3951","authenticated-orcid":true,"given":"T. R.","family":"Kannan","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02f6dcw23","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Microbiology, Immunology and Molecular Genetics, The University of Texas at San Antonio","place":["San Antonio, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1038\/35080089"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1128\/microbiolspec.VMBF-0012-2015"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-2958.2010.07092.x"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/24.22.4420"},{"key":"e_1_3_3_6_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/28.17.3278"},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.17.4.697-728.2004"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.00114-16"},{"key":"e_1_3_3_9_2","doi-asserted-by":"publisher","DOI":"10.3389\/fmicb.2016.00023"},{"key":"e_1_3_3_10_2","unstructured":"CDC. 2024. Mycoplasma pneumoniae infections have been increasing. Centers for Disease Control and Prevention. Available from: 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