Comparison of O-Antigen Gene Clusters of All O-Serogroups of Escherichia coli and Proposal for Adopting a New Nomenclature for O-Typing

• Published in: PloS one Vol. 11; no. 1; p. e0147434
• Main Authors: DebRoy, Chitrita, Fratamico, Pina M, Yan, Xianghe, Baranzoni, GianMarco, Liu, Yanhong, Needleman, David S, Tebbs, Robert, O'Connell, Catherine D, Allred, Adam, Swimley, Michelle, Mwangi, Michael, Kapur, Vivek, Raygoza Garay, Juan A, Roberts, Elisabeth L, Katani, Robab
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 29-01-2016; Public Library of Science (PLoS)
• Subjects: Adaptive systems; Agglutination; Agglutination Tests; Agriculture; Antigenic determinants; Antigens; Antisera; Biology and Life Sciences; Biomarkers; Biosynthesis; Classification; Clusters; Comparative analysis; Cross Reactions; Deoxyribonucleic acid; Diagnostic systems; DNA; E coli; Escherichia coli; Escherichia coli - classification; Escherichia coli - genetics; Escherichia coli Proteins - genetics; Food safety; Gene clusters; Gene sequencing; Genes; Genetic aspects; Glycosyltransferases - genetics; Host-pathogen interactions; Humans; Identification; Identification and classification; Immune Sera - chemistry; Immune system; Immunogenicity; Insertion sequences; Laboratories; Life sciences; Lipopolysaccharides; Medicine and Health Sciences; Membrane Transport Proteins - genetics; Multigene Family; Nucleotidyltransferases - genetics; O Antigens - classification; O Antigens - genetics; Pathogenesis; Phylogeny; Physiological aspects; Research and Analysis Methods; Sequence Analysis, DNA; Serogroup; Serotyping; Serotyping - methods; Sugar; Terminology as Topic; Typing; Vaccines; Veterinary medicine; Virulence; Virulence factors; United States
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0147434

Escherichia coli strains are classified based on O-antigens that are components of the lipopolysaccharide (LPS) in the cell envelope. O-antigens are important virulence factors, targets of both the innate and adaptive immune system, and play a role in host-pathogen interactions. Because they are highly immunogenic and display antigenic specificity unique for each strain, O-antigens are the biomarkers for designating O-types. Immunologically, 185 O-serogroups and 11 OX-groups exist for classification. Conventional serotyping for O-typing entails agglutination reactions between the O-antigen and antisera generated against each O-group. The procedure is labor intensive, not always accurate, and exhibits equivocal results. In this report, we present the sequences of 71 O-antigen gene clusters (O-AGC) and a comparison of all 196 O- and OX-groups. Many of the designated O-types, applied for classification over several decades, exhibited similar nucleotide sequences of the O-AGCs and cross-reacted serologically. Some O-AGCs carried insertion sequences and others had only a few nucleotide differences between them. Thus, based on these findings, it is proposed that several of the E. coli O-groups may be merged. Knowledge of the O-AGC sequences facilitates the development of molecular diagnostic platforms that are rapid, accurate, and reliable that can replace conventional serotyping. Additionally, with the scientific knowledge presented, new frontiers in the discovery of biomarkers, understanding the roles of O-antigens in the innate and adaptive immune system and pathogenesis, the development of glycoconjugate vaccines, and other investigations, can be explored.