RESEARCH ARTICLE


Genomic Comparison of the Closely Related Salmonella enterica Serovars Enteritidis and Dublin



Laura Betancor a, b, Lucía Yim a, Arací Martínez a, b, Maria Fookesc, Sebastian Sasias a, Felipe Schelotto b, Nicholas Thomson c, Duncan Maskell d, José A Chabalgoity a, *
a Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Av. A. Navarro 3051, CP 11600, Montevideo, Uruguay
b Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Av. A. Navarro 3051, CP 11600, Montevideo, Uruguay
c The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
d Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK


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Creative Commons License
© Betancor et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Av. A. Navarro 3051, CP 11600, Montevideo, Uruguay; Tel: +59824871288 ext. 1120; Fax: +59824873073; E-mail: jachabal@higiene.edu.uy


Abstract

The Enteritidis and Dublin serovars of Salmonella enterica are closely related, yet they differ significantly in pathogenicity and epidemiology. S. Enteritidis is a broad host range serovar that commonly causes gastroenteritis and infrequently causes invasive disease in humans. S. Dublin mainly colonizes cattle but upon infecting humans often results in invasive disease.To gain a broader view of the extent of these differences we conducted microarray-based comparative genomics between several field isolates from each serovar. Genome degradation has been correlated with host adaptation in Salmonella, thus we also compared at whole genome scale the available genomic sequences of them to evaluate pseudogene composition within each serovar.

Microarray analysis revealed 3771 CDS shared by both serovars while 33 were only present in Enteritidis and 87 were exclusive to Dublin. Pseudogene evaluation showed 177 inactive CDS in S. Dublin which correspond to active genes in S. Enteritidis, nine of which are also inactive in the host adapted S. Gallinarum and S. Choleraesuis serovars. Sequencing of these 9 CDS in several S. Dublin clinical isolates revealed that they are pseudogenes in all of them, indicating that this feature is not peculiar to the sequenced strain. Among these CDS, shdA (Peyer´s patch colonization factor) and mglA (galactoside transport ATP binding protein), appear also to be inactive in the human adapted S. Typhi and S. Paratyphi A, suggesting that functionality of these genes may be relevant for the capacity of certain Salmonella serovars to infect a broad range of hosts.

Keywords: Comparative genomics, Host specificity, Pseudogenes, Salmonella, S. Dublin, S. Enteritidis.