Hsieh P.-F.Wu M.-C.Yang F.-L.Chen C.-T.Lou T.-C.Chen Y.-Y.Wu S.-H.JIN-CHUAN SHEUJIN-TOWN WANG2019-09-022019-09-0220141664-302Xhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84987836155&doi=10.3389%2ffmicb.2014.00608&partnerID=40&md5=0b03caad0ff2ace167a1f1289de4eca7https://scholars.lib.ntu.edu.tw/handle/123456789/417147In the O1 strain of Klebsiella, the lipopolysaccharide (LPS) O-antigen is composed of D-galactan I and D-galactan II. Although the composition of the O1 antigen of Klebsiella was resolved more than two decades, the genetic locus involved in the biosynthesis of D-galactan II and the role of D-galactan II in bacterial pathogenesis remain unclear. Here, we report the identification of the D-galactan II-synthesizing genes by screening a transposon mutant library of an acapsulated Klebsiella pneumoniae O1 strain with bacteriophage. K. pneumoniae strain deleted for wbbY exhibited abrogated D-galactan II production; altered serum resistance and attenuation of virulence. Serologic analysis of K. pneumoniae clinical isolates demonstrated that D-galactan II was more prevalent in community-acquired pyogenic liver abscess (PLA)-causing strains than in non-tissue-invasive strains. WbbY homologs, WbbZ homologs, and lipopolysaccharide structures based on D-galactan II also were present in several Gram-negative bacteria. Immunization of mice with the magA-mutant (K- 1 O1) (that is, with a LPS D-galactan II-producing strain) provided protection against infection with an O1:K2 PLA strain. Our findings indicate that both WbbY and WbbZ homologs are sufficient for the synthesis of D-galactan II. D-galactan II represents an immunodominant antigen; is conserved among multiple species of Gram-negative bacteria and could be a useful vaccine candidate. ? 2014 Hsieh, Wu, Yang, Chen, Lou, Chen, Wu, Sheu and Wang.en-US[SDGs]SDG3antiD Gal II immunoglobulin G; bacterial antigen; DNA homolog; galactan; galactan II; glycosyltransferase; immunoglobulin G; Klebsiella pneumoniae O1 antigen; pACYC184 derived plasmid; plasmid vector; unclassified drug; animal experiment; animal model; animal tissue; Article; bacterial colonization; bacterial gene; bacterial virulence; bacteriophage; bacterium isolation; colony forming unit; controlled study; DNA sequence; female; gene deletion; gene locus; immunization; Klebsiella pneumoniae; mouse; mutant; nonhuman; nuclear magnetic resonance; nucleotide sequence; polymerase chain reaction; pyogenic liver abscess; transposon; WbbY gene; WbbZ genejournal article10.3389/fmicb.2014.006082-s2.0-84987836155