{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T08:57:20Z","timestamp":1791277040213,"version":"4.1.0"},"reference-count":60,"publisher":"National Academy of Sciences","issue":"30","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2004,7,27]]},"abstract":"<jats:p>\n                    Group B\n                    <jats:italic>Streptococcus<\/jats:italic>\n                    (GBS) is the leading cause of human neonatal sepsis and meningitis. The GBS capsular polysaccharide is a major virulence factor and the active principle of vaccines in phase II trials. All GBS capsules have a terminal \u03b12\u20133-linked sialic acid [\n                    <jats:italic>N<\/jats:italic>\n                    -acetylneuraminic acid (Neu5Ac)], which interferes with complement-mediated killing. We show here that some of the Neu5Ac residues of the GBS type III capsule are O-acetylated at carbon position 7, 8, or 9, a major modification evidently missed in previous studies. Data are consistent with initial O-acetylation at position 7, and subsequent migration of the\n                    <jats:italic>O<\/jats:italic>\n                    -acetyl ester at positions 8 and 9. O-acetylation was also present on several other GBS serotypes (Ia, Ib, II, V, and VI). Deletion of the CMP-Neu5Ac synthase gene\n                    <jats:italic>neu<\/jats:italic>\n                    A by precise, in-frame allelic replacement gave intracellular accumulation of O-acetylated Neu5Ac, whereas overexpression markedly decreased O-acetylation. Given the known GBS Neu5Ac biosynthesis pathway, these data indicate that O-acetylation occurs on free Neu5Ac, competing with the CMP-Neu5Ac synthase. O-acetylation often generates immunogenic epitopes on bacterial capsular polysaccharides and can modulate human alternate pathway complement activation. Thus, our discovery has important implications for GBS pathogenicity, immunogenicity, and vaccine design.\n                  <\/jats:p>","DOI":"10.1073\/pnas.0403010101","type":"journal-article","created":{"date-parts":[[2004,7,19]],"date-time":"2004-07-19T20:17:21Z","timestamp":1090268241000},"page":"11123-11128","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":146,"title":["Discovery and characterization of sialic acid O-acetylation in group B\n                    <i>Streptococcus<\/i>"],"prefix":"10.1073","volume":"101","author":[{"given":"Amanda L.","family":"Lewis","sequence":"first","affiliation":[{"name":"Division of Biological Sciences and Departments of Pediatrics, Medicine, and Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Victor","family":"Nizet","sequence":"additional","affiliation":[{"name":"Division of Biological Sciences and Departments of Pediatrics, Medicine, and Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ajit","family":"Varki","sequence":"additional","affiliation":[{"name":"Division of Biological Sciences and Departments of Pediatrics, Medicine, and Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2004,7,19]]},"reference":[{"key":"e_1_3_2_1_2","doi-asserted-by":"publisher","DOI":"10.1016\/S1473-3099(03)00577-2"},{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1086\/322696"},{"key":"e_1_3_2_3_2","first-page":"498","volume":"96","year":"2000","unstructured":"Campbell, J. 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