The global population structure and evolutionary history of the acquisition of major virulence factor-encoding genetic elements in Shiga toxin-producing Escherichia coli O121:H19.
Microb Genom
; 7(12)2021 12.
Article
en En
| MEDLINE
| ID: mdl-34878971
ABSTRACT
Shiga toxin (Stx)-producing Escherichia coli (STEC) are foodborne pathogens causing serious diseases, such as haemorrhagic colitis and haemolytic uraemic syndrome. Although O157H7 STEC strains have been the most prevalent, incidences of STEC infections by several other serotypes have recently increased. O121H19 STEC is one of these major non-O157 STECs, but systematic whole genome sequence (WGS) analyses have not yet been conducted on this STEC. Here, we performed a global WGS analysis of 638 O121H19 strains, including 143 sequenced in this study, and a detailed comparison of 11 complete genomes, including four obtained in this study. By serotype-wide WGS analysis, we found that O121H19 strains were divided into four lineages, including major and second major lineages (named L1 and L3, respectively), and that the locus of enterocyte effacement (LEE) encoding a type III secretion system (T3SS) was acquired by the common ancestor of O121H19. Analyses of 11 complete genomes belonging to L1 or L3 revealed remarkable interlineage differences in the prophage pool and prophage-encoded T3SS effector repertoire, independent acquisition of virulence plasmids by the two lineages, and high conservation in the prophage repertoire, including that for Stx2a phages in lineage L1. Further sequence determination of complete Stx2a phage genomes of 49 strains confirmed that Stx2a phages in lineage L1 are highly conserved short-tailed phages, while those in lineage L3 are long-tailed lambda-like phages with notable genomic diversity, suggesting that an Stx2a phage was acquired by the common ancestor of L1 and has been stably maintained. Consistent with these genomic features of Stx2a phages, most lineage L1 strains produced much higher levels of Stx2a than lineage L3 strains. Altogether, this study provides a global phylogenetic overview of O121H19 STEC and shows the interlineage genomic differences and the highly conserved genomic features of the major lineage within this serotype of STEC.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Factores de Virulencia
/
Escherichia coli Shiga-Toxigénica
/
Secuenciación Completa del Genoma
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Microb Genom
Año:
2021
Tipo del documento:
Article
País de afiliación:
Japón