TY - JOUR

T1 - Analysis of the contribution of bacteriophage ST64B to in vitro virulence traits of Salmonella enterica serovar Typhimurium

AU - Herrero Fresno, Ana

AU - Leekitcharoenphon, Pimlapas

AU - Hendriksen, Rene S.

AU - Olsen, John Elmerdahl

AU - Aarestrup, Frank Møller

PY - 2014

Y1 - 2014

N2 - The comparison of the publicly available genomes of the virulent Salmonella serovar Typhimurium strains SL1344, 14028s, D23580 to that of the virulence attenuated isolate LT2 revealed the absence of a full sequence of bacteriophage ST64B in the latter. Four selected ST64B regions of unknown function (sb7-sb11, sb46, sb49-sb50, and sb54) were mapped by PCR in two strains collections; 1) 310 isolates of S. Typhimurium from human blood or stool samples and from food, animal and environmental reservoirs, and 2) 90 isolates belonging to other serovars. The region sb49-sb50 was found to be unique to S. Typhimurium and was strongly associated to strains isolated from blood samples (100% and 28.4% of the blood and non-blood isolates, respectively). The region was cloned into LT2 and knocked out in SL1344 and these strains were compared to wild type isogenic strains in in vitro assays used to predict virulence association. No difference in invasion of the Int407 human cell line was observed between the wild type and mutated strains, but the isolate carrying the whole ST64B prophage was found to have a slightly better survival in blood. The study showed a high prevalence and a strong association between the prophage ST64B and isolates of S. Typhimurium collected from blood, and may indicate that such strains constitute a selected subpopulation within this serovar. Further studies are indicated to determine whether the slight increase in blood survival observed in the strain carrying ST64B genes is of paramount for systemic infections.

AB - The comparison of the publicly available genomes of the virulent Salmonella serovar Typhimurium strains SL1344, 14028s, D23580 to that of the virulence attenuated isolate LT2 revealed the absence of a full sequence of bacteriophage ST64B in the latter. Four selected ST64B regions of unknown function (sb7-sb11, sb46, sb49-sb50, and sb54) were mapped by PCR in two strains collections; 1) 310 isolates of S. Typhimurium from human blood or stool samples and from food, animal and environmental reservoirs, and 2) 90 isolates belonging to other serovars. The region sb49-sb50 was found to be unique to S. Typhimurium and was strongly associated to strains isolated from blood samples (100% and 28.4% of the blood and non-blood isolates, respectively). The region was cloned into LT2 and knocked out in SL1344 and these strains were compared to wild type isogenic strains in in vitro assays used to predict virulence association. No difference in invasion of the Int407 human cell line was observed between the wild type and mutated strains, but the isolate carrying the whole ST64B prophage was found to have a slightly better survival in blood. The study showed a high prevalence and a strong association between the prophage ST64B and isolates of S. Typhimurium collected from blood, and may indicate that such strains constitute a selected subpopulation within this serovar. Further studies are indicated to determine whether the slight increase in blood survival observed in the strain carrying ST64B genes is of paramount for systemic infections.

KW - Faculty of Health and Medical Sciences

KW - salmonella

KW - virulens

U2 - 10.1099/jmm.0.068221-0

DO - 10.1099/jmm.0.068221-0

M3 - Journal article

C2 - 24324031

VL - 63

SP - 331

EP - 342

JO - Journal of Medical Microbiology

JF - Journal of Medical Microbiology

SN - 0022-2615

IS - 3

ER -