|KATANI, ROBAB - Pennsylvania State University|
|MOREAU, MATHEW - Pennsylvania State University|
|GARAY, JUAN - Pennsylvania State University|
|COTE, REBECCA - Pennsylvania State University|
|LI, LINGLING - Pennsylvania State University|
|DEBROY, CHITRITA - Pennsylvania State University|
|MWANGI, MICHAEL - Pennsylvania State University|
|KAPUR, VIVEK - Pennsylvania State University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2015
Publication Date: 6/1/2015
Citation: Katani, R., Moreau, M.R., Kudva, I.T., Carter, M.Q., Garay, J.A., Cote, R., Li, L., Arthur, T.M., Debroy, C., Mwangi, M., Kapur, V. 2015. Comparative genomic analysis and adherence characteristics of supershedder strains of Escherichia coli O157:H7 [abstract]. American Society for Microbiology. Abstract No. 973.
Technical Abstract: Shiga toxin-producing Escherichia coli O157:H7 (O157) is a zoonotic foodborne pathogen of major public health concern that results in considerable intestinal and extra-intestinal illness in humans. Asymptomatic cattle are the primary reservoir of O157 and harbor the pathogen at the terminal recto-anal junction (RAJ). A small subset of cattle, termed supershedders (SS), shed O157 at a rate that is several orders of magnitude greater than other colonized cattle. Epidemiological studies have indicated that while the number of SS animals on farms is less than 10%, they are responsible for 99% of the O157 shed into the environment. To understand the molecular mechanisms contributing to the supershedding, we recently described the first complete genome sequence of a SS strain of O157, SS17 (Accession No. CP008805). To enable rigorous comparative genomic analyses of SS isolates, we here report the second complete genome sequence of another SS strain of O157, SS52 (Accession No. CP010304). The genome of SS52 is 5.4Mbp and carries one plasmid, pO157 (94kb). Whole genome alignments revealed that both SS strains cluster closely with the lineage I/II spinach outbreak isolates (EC4115 and TW14359) as compared with lineage I outbreak isolates (Sakai and EDL933) or the bovine lineage II isolates. Comparative analyses revealed that SS52 exhibits a translocation in a 55kb bacteriophage-enriched area; a 357kb area of inversion that included fim operon; and one 4kb phage-related area of deletion. To elucidate molecular mechanisms contributing to the adherence and colonization of SS strains to the bovine RAJ a series of deletion mutants were constructed in the fimbrial and non-fimbrial genes and operons in SS17, SS52, and EDL933 (a reference isolate). The adherence phenotype of the parental SS strains and mutants was evaluated on bovine stratified squamous epithelial (RSE) cells. SS isolates have distinctive genomic features and manifest strong hyper-aggregative phenotype on RSE cells distinct from moderate, diffuse adherence on HEp-2 cells. Parental strains and type 1 fim operon mutants of SS17 and SS52 have similar adherence patterns of strong, aggregative, where as SS17 delta fimH shows a moderate, diffuse adherence pattern on the RSE cells. Comparative adherence of SS strains to leafy greens (spinach) is also under investigation.