{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T15:36:37Z","timestamp":1790264197254,"version":"4.1.0"},"reference-count":53,"publisher":"American Society for Microbiology","issue":"4","license":[{"start":{"date-parts":[[2013,7,16]],"date-time":"2013-07-16T00:00:00Z","timestamp":1373932800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/"},{"start":{"date-parts":[[2013,8,30]],"date-time":"2013-08-30T00:00:00Z","timestamp":1377820800000},"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":["mBio"],"published-print":{"date-parts":[[2013,8,30]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            Expression of capsular polysaccharides is a variable trait often associated with more-virulent forms of a bacterial species. For example, typhoid fever is caused by the capsulated\n            <jats:named-content content-type=\"genus-species\">Salmonella enterica<\/jats:named-content>\n            serovar Typhi, while nontyphoidal\n            <jats:italic>Salmonella<\/jats:italic>\n            serovars associated with gastroenteritis are noncapsulated. Here we show that optimization of the immune evasive properties conferred by the virulence-associated (Vi) capsular polysaccharide involved an additional alteration to the cell envelope of\n            <jats:italic>S<\/jats:italic>\n            . Typhi, namely inactivation of the\n            <jats:italic>fepE<\/jats:italic>\n            gene, encoding the regulator of very-long O-antigen chains. Introduction of the capsule-encoding\n            <jats:italic>viaB<\/jats:italic>\n            locus into the nontyphoidal\n            <jats:named-content content-type=\"genus-species\">S. enterica<\/jats:named-content>\n            serovar Typhimurium reduced complement deposition\n            <jats:italic>in vitro<\/jats:italic>\n            and intestinal inflammation in a mouse colitis model. However, both phenotypes were markedly enhanced when the\n            <jats:italic>viaB<\/jats:italic>\n            locus was introduced into an\n            <jats:italic>S<\/jats:italic>\n            . Typhimurium\n            <jats:italic>fepE<\/jats:italic>\n            mutant, which lacks very-long O-antigen chains. Collectively, these data suggest that during the evolution of the\n            <jats:italic>S<\/jats:italic>\n            . Typhi lineage, loss of very-long O-antigen chains by pseudogene formation was an adaptation to maximize the anti-inflammatory properties of the Vi capsular polysaccharide.\n          <\/jats:p>\n          <jats:p>\n            <jats:bold>IMPORTANCE<\/jats:bold>\n            Genomic comparison illustrates that acquisition of virulence factors by horizontal gene transfer is an important contributor to the evolution of enteric pathogens. Acquisition of complex virulence traits commonly involves horizontal transfer of a large gene cluster, and integration of the gene cluster into the host genome results in the formation of a pathogenicity island. Acquisition of the virulence-associated (Vi) capsular polysaccharide encoded by SPI7 (\n            <jats:italic>Salmonella<\/jats:italic>\n            pathogenicity island 7) was accompanied in the human-adapted\n            <jats:named-content content-type=\"genus-species\">Salmonella enterica<\/jats:named-content>\n            serovar Typhi by inactivation of the\n            <jats:italic>fepE<\/jats:italic>\n            gene, encoding the regulator of very-long O-antigen chains. We show that the resulting loss of very-long O-antigen chains was an important mechanism for maximizing immune evasion mediated by the Vi capsular polysaccharide. These data suggest that successful incorporation of a capsular polysaccharide requires changes in the cell envelope of the hosting pathogen.\n          <\/jats:p>","DOI":"10.1128\/mbio.00232-13","type":"journal-article","created":{"date-parts":[[2013,7,17]],"date-time":"2013-07-17T02:12:18Z","timestamp":1374027138000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":55,"title":["Loss of Very-Long O-Antigen Chains Optimizes Capsule-Mediated Immune Evasion by Salmonella enterica Serovar Typhi"],"prefix":"10.1128","volume":"4","author":[{"given":"Robert W.","family":"Crawford","sequence":"first","affiliation":[{"name":"Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tamding","family":"Wangdi","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alanna M.","family":"Spees","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariana N.","family":"Xavier","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ren\u00e9e M.","family":"Tsolis","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andreas J.","family":"B\u00e4umler","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, Davis, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","first-page":"63","article-title":"Enteric fever: a clinicopathologic study of 104 cases","volume":"69","author":"Nasrallah SM","year":"1978","unstructured":"NasrallahSM NassarVH . 1978. 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