{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T00:13:09Z","timestamp":1789863189457,"version":"4.0.1"},"reference-count":38,"publisher":"American Society for Microbiology","issue":"7","license":[{"start":{"date-parts":[[2012,7,1]],"date-time":"2012-07-01T00:00:00Z","timestamp":1341100800000},"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":["Infect Immun"],"published-print":{"date-parts":[[2012,7]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            The capsule of\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">Neisseria meningitidis<\/jats:named-content>\n            is the major virulence factor that enables this bacterium to overcome host immunity elicited by complement and phagocytes, rendering it capable of surviving in blood. As such, nonencapsulated\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">N. meningitidis<\/jats:named-content>\n            isolates are generally considered nonpathogenic. Here, we consider the inherent virulence of two nonencapsulated\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">N. meningitidis<\/jats:named-content>\n            isolates obtained from our national surveillance of infected blood cultures in Canada. Capsule deficiency of both strains was confirmed by serology and PCR for the\n            <jats:italic>ctrA<\/jats:italic>\n            to\n            <jats:italic>ctrD<\/jats:italic>\n            genes and\n            <jats:italic>siaA<\/jats:italic>\n            to\n            <jats:italic>siaC<\/jats:italic>\n            genes, as well as\n            <jats:italic>siaD<\/jats:italic>\n            genes specific to serogroups B, C, Y, and W135. In both strains, the capsule synthesis genes were replaced by the capsule null locus,\n            <jats:italic>cnl-2<\/jats:italic>\n            . In accordance with a lack of capsule, both strains were fully susceptible to killing by both human and baby rabbit complement. However, in the presence of cytidine-5\u2032 monophospho-\n            <jats:italic>N<\/jats:italic>\n            -acetylneuraminic acid (CMP-NANA), allowing for lipooligosaccharide (LOS) sialylation, a significant increase of resistance to complement killing was observed. Mass spectrometry of purified LOS did not reveal any uncommon modifications that would explain their invasive phenotype. Finally, in a mouse intraperitoneal challenge model, these nonencapsulated isolates displayed enhanced virulence relative to an isogenic mutant of serogroup B strain MC58 lacking capsule (MC58\u0394\n            <jats:italic>siaD<\/jats:italic>\n            ). Virulence of all nonencapsulated isolates tested was below that of encapsulated serogroup B strains MC58 and B16B6. However, whereas no mortality was observed with MC58\u0394\n            <jats:italic>siaD<\/jats:italic>\n            , 5\/10 mice succumbed to infection with strain 2275 and 2\/11 mice succumbed to strain 2274. Our results suggest the acquisition of a new virulence phenotype by these nonencapsulated strains.\n          <\/jats:p>","DOI":"10.1128\/iai.00293-12","type":"journal-article","created":{"date-parts":[[2012,4,17]],"date-time":"2012-04-17T05:26:55Z","timestamp":1334640415000},"page":"2346-2353","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":39,"title":["Invasive Potential of Nonencapsulated Disease Isolates of Neisseria meningitidis"],"prefix":"10.1128","volume":"80","author":[{"given":"Kay O.","family":"Johswich","sequence":"first","affiliation":[{"name":"Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianwei","family":"Zhou","sequence":"additional","affiliation":[{"name":"Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dennis K. S.","family":"Law","sequence":"additional","affiliation":[{"name":"Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Frank","family":"St. Michael","sequence":"additional","affiliation":[{"name":"Institute for Biological Sciences, National Research Council, Ottawa, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shannon E.","family":"McCaw","sequence":"additional","affiliation":[{"name":"Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Frances B.","family":"Jamieson","sequence":"additional","affiliation":[{"name":"Public Health Laboratories, Public Health Ontario, Toronto, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew D.","family":"Cox","sequence":"additional","affiliation":[{"name":"Institute for Biological Sciences, National Research Council, Ottawa, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raymond S. W.","family":"Tsang","sequence":"additional","affiliation":[{"name":"Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Scott D.","family":"Gray-Owen","sequence":"additional","affiliation":[{"name":"Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1574-6968.1987.tb02626.x"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1139\/m79-113"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.42.4.1764-1765.2004"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1574-6968.1998.tb12862.x"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1017\/S0950268896007261"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1099\/00221287-148-6-1813"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1086\/653583"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1086\/512084"},{"key":"e_1_3_2_10_2","first-page":"241","article-title":"Animal models for meningococcal disease","volume":"66","author":"Gorringe AR","year":"2001","unstructured":"GorringeARReddinKMVoetPPoolmanJT. 2001. 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Capsular operons. Methods Mol. Med. 67:187\u2013201.","journal-title":"Methods Mol. 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