Molecular characterization of Salmonella enterica subsp. enterica serovar choleraesuis field isolates and differentiation from homologous live vaccine strains suisaloral and SC-54

Abstract

Four independent molecular methods were used to characterize the Salmonella enterica subsp. enterica serovar choleraesuis live vaccine strains SC-54 and Suisaloral and to differentiate them from S. choleraesuis field isolates. Plasmid analysis revealed the presence of seven plasmid profiles. A virulence plasmid of 52-kbp was identified by hybridization with an spvB-spvC gene probe in each of the S. choleraesuis field isolates and in the Suisaloral vaccine strain, but not in the SC-54 vaccine strain. Ribotyping, performed with a gene probe that recognized 23S, 16S, and 5S rRNA genes, resulted in three closely related hybridization patterns. IS200 elements were not detected in the field isolates or in the two S. choleraesuis live vaccine strains. Macrorestriction analysis with the enzymes XbaI, SpeI, NotI, and SfiI differentiated the 29 S. choleraesuis strains included in this study into 10, 13, 8, and 13 different fragment patterns, respectively. While the Suisaloral vaccine strain showed a unique XbaI macrorestriction pattern, the fragment patterns of the SC-54 strain obtained with the different enzymes were shared by 2 to 18 S. choleraesuis field strains. A combination of plasmid analysis and macrorestriction analysis proved to be most suitable for the molecular typing of S. choleraesuis and the differentiation of both live vaccine strains from field isolates of this serovar.

Molecular characterization of Salmonella enterica subsp. enterica serovar Typhimurium DT009 isolates: differentiation of the live vaccine strain Zoosaloral from field isolates

“…enterica isolates of various serovars [11]. Thus, molecular typing systems which are based on plasmid analysis, ribotyping, IS200 typing and macrorestriction analysis have been established for a number of serovars, such as Typhimurium [1,2,12], Enteritidis [13^16], Dublin [8,17], Choleraesuis [9] or Hadar [18]. These typing systems enable the identi¢cation of single Salmonella isolates and their di¡erentiation from those of the same serovar and occasionally even from those of the same phage type [12^14,16].…”

“…These typing systems enable the identi¢cation of single Salmonella isolates and their di¡erentiation from those of the same serovar and occasionally even from those of the same phage type [12^14,16]. In the case of the Salmonella live vaccine strains Zoosaloral H [1,2], Bovisaloral [8] and Suisaloral [9], molecular typing provided means for an exact and reliable di¡erentiation of the vaccine strains from avian S. Typhimurium, bovine S. Dublin, and porcine S. Choleraesuis ¢eld isolates. In this study, we investigated whether, and if so which, molecular typing methods were suitable to distinguish between the S. Typhimurium live vaccine strain Zoosaloral and the most closely related S. Typhimurium ¢eld isolates, namely those of the same phage type.…”

“…The extraction of whole cell DNA for ribotyping and IS200 typing as well as restriction analyses of plasmid DNA and whole cellular DNA followed previously described protocols [1]. Speci¢c gene probes for the spvB/spvC virulence genes, 16S-23S-5S rRNA and the insertion element IS200, all labelled by the enhanced chemiluminescence system (ECL, Amersham-Buchler), were used in Southern blot hybridization experiments [1,8,9]. Whole cell DNA for pulsed-¢eld gel electrophoresis experiments was prepared as described [2] and digested with XbaI (Boehringer, Mannheim, Germany), SpeI (BioLabs, Bad Schwalbach, Germany), or BlnI (Amersham-Buch-ler).…”

Molecular analysis of tetracycline resistance in Salmonella enterica subsp. enterica serovars Typhimurium, Enteritidis, Dublin, Choleraesuis, Hadar and Saintpaul: construction and application of specific gene probes

“…Enteritidis isolates, was performed by the National Reference Center for Salmonellae and other Enterics in Wernigerode, Germany. The majority of the isolates of the six serovars used in this study had previously been investigated for their clonal relationships by applying molecular typing methods, including macrorestriction analyses, ribotyping, IS 200 typing and plasmid profiling ( Schwarz and Liebisch 1994a, b, 1996b; Liebisch and Schwarz 1996a; Weide‐Botjes et al . 1996, 1998a, b; Frech and Schwarz 1998b).…”

Subtracted restriction fingerprinting – a new typing technique using magnetic capture of tagged restriction fragments

“…The gene probes used for ribotyping Salmonella vary considerably as do the restriction endonucleases used for digesting the whole cell DNA. A summary of the various probes and restriction endonucleases used for ribotyping of S. Enteritidis is given by Weide‐Botjes et al [18] and illustrates that results obtained under such non‐standardised conditions are not comparable. For ribotyping of Salmonella isolates, an automated RiboPrinter™ has also been used successfully [19].…”