scholarly journals Aggregation via the Red, Dry, and Rough Morphotype Is Not a Virulence Adaptation in Salmonella enterica Serovar Typhimurium

2008 ◽  
Vol 76 (3) ◽  
pp. 1048-1058 ◽  
Author(s):  
A. P. White ◽  
D. L. Gibson ◽  
G. A. Grassl ◽  
W. W. Kay ◽  
B. B. Finlay ◽  
...  
Keyword(s):  
In Vivo Imaging ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Primary Role ◽  
Wild Type ◽  
Serovar Typhimurium ◽  
Cell Densities ◽  
Two Populations

ABSTRACT The Salmonella rdar (red, dry, and rough) morphotype is an aggregative and resistant physiology that has been linked to survival in nutrient-limited environments. Growth of Salmonella enterica serovar Typhimurium was analyzed in a variety of nutrient-limiting conditions to determine whether aggregation would occur at low cell densities and whether the rdar morphotype was involved in this process. The resulting cultures consisted of two populations of cells, aggregated and nonaggregated, with the aggregated cells preferentially displaying rdar morphotype gene expression. The two groups of cells could be separated based on the principle that aggregated cells were producing greater amounts of thin aggregative fimbriae (Tafi or curli). In addition, the aggregated cells retained some physiological characteristics of the rdar morphotype, such as increased resistance to sodium hypochlorite. Competitive infection experiments in mice showed that nonaggregative ΔagfA cells outcompeted rdar-positive wild-type cells in all tissues analyzed, indicating that aggregation via the rdar morphotype was not a virulence adaptation in Salmonella enterica serovar Typhimurium. Furthermore, in vivo imaging experiments showed that Tafi genes were not expressed during infection but were expressed once Salmonella was passed out of the mice into the feces. We hypothesize that the primary role of the rdar morphotype is to enhance Salmonella survival outside the host, thereby aiding in transmission.

scholarly journals The enzyme phosphoglucomutase (Pgm) is required by Salmonella enterica serovar Typhimurium for O-antigen production, resistance to antimicrobial peptides and in vivo fitness

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3403-3410 ◽  
Author(s):  
G. K. Paterson ◽  
D. B. Cone ◽  
S. E. Peters ◽  
D. J. Maskell
Keyword(s):  
Antimicrobial Peptides ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Live Attenuated Vaccine ◽  
Antigen Production ◽  
O Antigen ◽  
Serovar Typhimurium

The enzyme phosphoglucomutase (Pgm) catalyses the interconversion of glucose 1-phosphate and glucose 6-phosphate and contributes to glycolysis and the generation of sugar nucleotides for biosynthesis. To assess the role of this enzyme in the biology of the pathogen Salmonella enterica serovar Typhimurium we have characterized a pgm deletion mutant in strain SL1344. Compared to SL1344, SL1344 pgm had impaired growth in vitro, was deficient in the ability to utilize galactose as a carbon source and displayed reduced O-antigen polymer length. The mutant was also more susceptible to antimicrobial peptides and showed decreased fitness in the mouse typhoid model. The in vivo phenotype of SL1344 pgm indicated a role for pgm in the early stages of infection, most likely through deficient O-antigen production. Although pgm mutants in other pathogens have potential as live attenuated vaccine strains, SL1344 pgm was not sufficiently attenuated for such use.

scholarly journals Effect of Inactivation of degS on Salmonella enterica Serovar Typhimurium In Vitro and In Vivo

2005 ◽  
Vol 73 (1) ◽  
pp. 459-463 ◽  
Author(s):  
Gary Rowley ◽  
Andrew Stevenson ◽  
Jan Kormanec ◽  
Mark Roberts
Keyword(s):  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Wild Type ◽  
Alternative Pathways ◽  
E Coli ◽  
Mammalian Tissues ◽  
Serovar Typhimurium

ABSTRACT The alternative sigma factor (RpoE σE) enables Salmonella enterica serovar Typhimurium to adapt to stressful conditions, such as oxidative stress, nutrient deprivation, and growth in mammalian tissues. Infection of mice by Salmonella serovar Typhimurium also requires σE. In Escherichia coli, activation of the σE pathway is dependent on proteolysis of the anti-sigma factor RseA and is initiated by DegS. DegS is also important in order for E. coli to cause extraintestinal infection in mice. We constructed a degS mutant of the serovar Typhimurium strain SL1344 and compared its behavior in vitro and in vivo with those of its wild-type (WT) parent and an isogenic rpoE mutant. Unlike E. coli degS strains, the Salmonella serovar Typhimurium degS strain grew as well as the WT strain at 42°C. The degS mutant survived very poorly in murine macrophages in vitro and was highly attenuated compared with the WT strain for both the oral and parenteral routes of infection in mice. However, the degS mutant was not as attenuated as the serovar Typhimurium rpoE mutant: 100- to 1,000-fold more degS bacteria than rpoE bacteria were present in the livers and spleens of mice 24 h after intraperitoneal challenge. In most assays, the rpoE mutant was more severely affected than the degS mutant and a σE-dependent reporter gene was more active in the degS mutant than the rpoE strain. These findings indicate that degS is important for activation of the σE pathway in serovar Typhimurium but that alternative pathways for σE activation probably exist.

scholarly journals Salmonella enterica Serovar Typhimurium NiFe Uptake-Type Hydrogenases Are Differentially Expressed In Vivo

2008 ◽  
Vol 76 (10) ◽  
pp. 4445-4454 ◽  
Author(s):  
Andrea L. Zbell ◽  
Susan E. Maier ◽  
Robert J. Maier
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Acid Stress ◽  
Wild Type ◽  
Reverse Transcription Pcr ◽  
Serovar Typhimurium ◽  
Low Levels ◽  
And Function ◽  
Mutant Cells

ABSTRACT Salmonella enterica serovar Typhimurium, a common enteric pathogen, possesses three NiFe uptake-type hydrogenases. The results from mouse infection studies suggest that the H2 oxidation capacity provided by these hydrogenases is important for virulence. Since the three enzymes are similar in structure and function, it may be expected that they are utilized under different locations and times during an infection. A recombination-based method to examine promoter activity in vivo (RIVET) was used to determine hydrogenase gene expression in macrophages, polymorphonuclear leukocyte (PMN)-like cells, and a mouse model of salmonellosis. The hyd and hya promoters showed increased expression in both murine macrophages and human PMN-like cells compared to that in the medium-only controls. Quantitative reverse transcription-PCR results suggested that hyb is also expressed in phagocytes. A nonpolar hya mutant was compromised for survival in macrophages compared to the wild type. This may be due to lower tolerance to acid stress, since the hya mutant was much more acid sensitive than the wild type. In addition, hya mutant cells were internalized by macrophages the same as wild-type cells. Mouse studies (RIVET) indicate that hyd is highly expressed in the liver and spleen early during infection but is expressed poorly in the ileum in infected animals. Late in the infection, the hyd genes were expressed at high levels in the ileum as well as in the liver and spleen. The hya genes were expressed at low levels in all locations tested. These results suggest that the hydrogenases are used to oxidize hydrogen in different stages of an infection.

scholarly journals Salmonella enterica serovar Typhimurium sseK3 induces apoptosis and enhances glycolysis in macrophages

2020 ◽  
Author(s):  
Chuan Yu ◽  
Fuyu Du ◽  
Chunjie Zhang ◽  
Yinju Li ◽  
Chengshui Liao ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Salmonella Enterica ◽  
Caspase 3 ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Caspase 8 ◽  
Wild Type ◽  
Caspase 9 ◽  
Serovar Typhimurium ◽  
The Relationship

Abstract Background: Salmonella enterica serovar Typhimurium ( S. Typhimurium) is an important infectious disease pathogen that can survive and replicate in macrophages. Glycolysis is essential for immune responses against S. Typhimurium infection in macrophages, and is also associated with apoptosis. S. Typhimurium secreted effector K3 (SseK3) was recently identified as a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis in cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in S. Typhimurium-infected macrophages. Results: Macrophages were infected with S. Typhimurium SL1344 wild-type (WT), Δ sseK3 mutant or sseK3 -complemented strain, and the effects of sseK3 on apoptosis and glycolysis were determined. The adherence and invasion in the Δ sseK3 mutant group were similar to that in the WT and sseK3 -complemented groups, indicating that SseK3 was not essential for the adherence and invasion of S. Typhimurium in macrophages. However, the percentage of apoptosis in the Δ sseK3 mutant group was much lower than that in the WT and sseK3 -complemented groups. Caspase-3, caspase-8, and caspase-9 enzyme activity in the Δ sseK3 mutant group were significantly lower than in the WT group and sseK3 -complemented groups, indicating that sseK3 could improve the caspase-3, caspase-8, and caspase-9 enzyme activity. We also found that there were no significant differences in pyruvic acid levels between the three groups, but the lactic acid level in the Δ sseK3 mutant group was much lower than that in the WT and sseK3 -complemented groups. The ATP levels in the Δ sseK3 mutant group were remarkably higher than those in the WT and sseK3 -complemented groups. These indicated that the sseK3 enhanced the level of glycolysis in macrophages infected by S. Typhimurium. Conclusions: S. Typhimurium sseK3 is likely involved in promoting macrophage apoptosis and modulating glycolysis in macrophages. Our results could improve our understanding of the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3 .

scholarly journals Constitutive Acid Sphingomyelinase Enhances Early and Late Macrophage Killing of Salmonella enterica Serovar Typhimurium

2007 ◽  
Vol 75 (11) ◽  
pp. 5346-5352 ◽  
Author(s):  
Bruce D. McCollister ◽  
Jesse T. Myers ◽  
Jessica Jones-Carson ◽  
Dennis R. Voelker ◽  
Andrés Vázquez-Torres
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Acid Sphingomyelinase ◽  
Wild Type ◽  
Serovar Typhimurium ◽  
Important Player ◽  
Phagocyte Oxidase ◽  
Macrophage Killing

ABSTRACT We have identified acid sphingomyelinase (ASM) as an important player in the early and late anti-Salmonella activity of macrophages. A functional ASM participated in the killing activity of macrophages against wild-type Salmonella enterica serovar Typhimurium. The role of ASM in early macrophage killing of Salmonella appears to be linked to an active NADPH phagocyte oxidase enzymatic complex, since the flavoprotein inhibitor diphenyleneiodonium not only blocked a productive respiratory burst but also abrogated the survival advantage of Salmonella in macrophages lacking ASM. Lack of ASM activity also increased the intracellular survival of an isogenic ΔspiC::FRT Salmonella strain deficient in a translocator and effector of the Salmonella pathogenicity island 2 (SPI2) type III secretion system, suggesting that the antimicrobial activity associated with ASM is manifested regardless of the SPI2 status of the bacteria. Constitutively expressed ASM is responsible for the role that this lipid-metabolizing hydrolase plays in the innate host defense of macrophages against Salmonella. Accordingly, the ASM activity and intracellular concentration and composition of ceramide, gangliosides, and neutral sphingolipids did not increase upon Salmonella infection. Salmonella triggered, nonetheless, a significant increase in the secreted fraction of ASM. Collectively, these findings have elucidated a novel role for constitutive ASM in the anti-Salmonella activity of murine macrophages.

scholarly journals Analysis of Spleen-Induced Fimbria Production in Recombinant AttenuatedSalmonella entericaSerovar Typhimurium Vaccine Strains

mBio ◽  
2017 ◽  
Vol 8 (4) ◽  
Author(s):  
Paweł Łaniewski ◽  
Chang-Ho Baek ◽  
Kenneth L. Roland ◽  
Roy Curtiss
Keyword(s):  
Salmonella Enterica ◽  
Protective Efficacy ◽  
The United States ◽  
Wild Type ◽  
Strong Immune Response ◽  
Food Borne ◽  
Serovar Typhimurium ◽  
Oral Doses

ABSTRACTSalmonella entericaserovar Typhimurium genome encodes 13 fimbrial operons. Most of the fimbriae encoded by these operons are not produced under laboratory conditions but are likely to be synthesizedin vivo. We used anin vivoexpression technology (IVET) strategy to identify four fimbrial operons,agf,saf,sti, andstcthat are expressed in the spleen. When any three of these operons were deleted, the strain retained wild-type virulence. However, when all four operons were deleted, the resulting strain was completely attenuated, indicating that these four fimbriae play functionally redundant roles critical for virulence. In mice, oral doses of as low as 1 × 105 CFU of the strain with four fimbrial operons deleted provided 100% protection against challenge with 1 × 109 CFU of wild-typeS. Typhimurium. We also examined the possible effect of these fimbriae on the ability of aSalmonellavaccine strain to deliver a guest antigen. We modified one of our established attenuated vaccine strains, χ9088, to delete three fimbrial operons while the fourth operon was constitutively expressed. Each derivative was modified to express theStreptococcus pneumoniaeantigen PspA. Strains that constitutively expressedsaforstcelicited a strong Th1 response with significantly greater levels of anti-PspA serum IgG and greater protective efficacy than strains carryingsaforstcdeletions. The isogenic strain in which all four operons were deleted generated the lowest anti-PspA levels and did not protect against challenge with virulentS. pneumoniae. Our results indicate that these fimbriae play important roles, as yet not understood, inSalmonellavirulence and immunogenicity.IMPORTANCESalmonella entericais the leading cause of bacterial food-borne infection in the United States. S. Typhimurium is capable of producing up to 13 distinct surface structures called fimbriae that presumably mediate its adherence to surfaces. The roles of most of these fimbriae in disease are unknown. Identifying fimbriae produced during infection will provide important insights into how these bacterial structures contribute to disease and potentially induce protective immunity toSalmonellainfection. We identified four fimbriae that are produced during infection. Deletion of all four of these fimbriae results in a significant reduction in virulence. We explored ways in which the expression of these fimbriae may be exploited for use in recombinantSalmonellavaccine strains and found that production of Saf and Stc fimbriae are important for generating a strong immune response against a vectored antigen. This work provides new insight into the role of fimbriae in disease and their potential for improving the efficacy ofSalmonella-based vaccines.

scholarly journals The Salmonella enterica serovar Typhimurium sseK3 induce cell apoptosis and enhance glycolysis in macrophages

2020 ◽  
Author(s):  
Chuan Yu ◽  
Fuyu Du ◽  
Chunjie Zhang ◽  
Yinju Li ◽  
Chengshui Liao ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Acid Level ◽  
Caspase 3 ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Caspase 8 ◽  
Wild Type ◽  
Caspase 9 ◽  
Serovar Typhimurium ◽  
The Relationship

Abstract Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important infectious disease pathogen. Recently, there are increasing researches about the relationship between apoptosis and glycolysis of cells. Previous studies have identified that S. Typhimurium secreted effector K3 (SseK3) is a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis of cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in macrophages. Results: The S. Typhimurium SL1344 wild-type (WT) group, ΔsseK3 mutant group and sseK3-complemented group were used to infect macrophages and the effects of sseK3 on apoptosis and glycolysis of macrophages were investigated. The adherence and invasion of ΔsseK3 mutant group for macrophages were similar to WT group and sseK3-complemented group, indicating that SseK3 did not play an important role in the adherence and invasion of S. Typhimurium for macrophages. However, the apoptosis percentage of the ΔsseK3 mutant group was much lower than WT group and sseK3-complemented group using flow cytometry. The caspase-3, caspase-8 and caspase-9 enzyme activity of the ΔsseK3 mutant group were decreased significantly compared with WT group and sseK3-complemented group, which suggested that sseK3 could improve the activities of caspase-3, caspase-8 and caspase-9 enzyme. We also found that the pyruvic acid level did not significantly change among ΔsseK3 mutant group, WT group and sseK3-complemented group, but the lactic acid level of ΔsseK3 mutant group was much lower than WT group and sseK3-complemented group. The ATP level of ΔsseK3 mutant group was remarkably higher than WT group and sseK3-complemented group. These indicated that the sseK3 enhanced the level of glycolysis of macrophages infected by S. Typhimurium. Conclusions: Our data showed that the sseK3 of S. Typhimurium involved in promoting macrophages apoptosis and influencing glycolysis levels of macrophages. These results may give a better clue about the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3.

scholarly journals Salmonella enterica serovar Typhimurium sseK3 induces apoptosis and enhances glycolysis in macrophages

2020 ◽  
Author(s):  
Chuan Yu ◽  
Fuyu Du ◽  
Chunjie Zhang ◽  
Yinju Li ◽  
Chengshui Liao ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Salmonella Enterica ◽  
Caspase 3 ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Caspase 8 ◽  
Wild Type ◽  
Caspase 9 ◽  
Serovar Typhimurium ◽  
The Relationship

Abstract Background: Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important infectious disease pathogen that can survive and replicate in macrophages. Glycolysis is essential for immune responses against S. Typhimurium infection in macrophages, and is also associated with apoptosis. S. Typhimurium secreted effector K3 (SseK3) was recently identified as a novel translated and secreted protein. However, there is no study about the role of sseK3 in the relationship between apoptosis and glycolysis in cells infected with S. Typhimurium. It is unclear whether this protein exerts a significant role in the progress of apoptosis and glycolysis in S. Typhimurium-infected macrophages.Results: Macrophages were infected with S. Typhimurium SL1344 wild-type (WT), ΔsseK3 mutant or sseK3-complemented strain, and the effects of sseK3 on apoptosis and glycolysis were determined. The adherence and invasion in the ΔsseK3 mutant group were similar to that in the WT and sseK3-complemented groups, indicating that SseK3 was not essential for the adherence and invasion of S. Typhimurium in macrophages. However, the percentage of apoptosis in the ΔsseK3 mutant group was much lower than that in the WT and sseK3-complemented groups. Caspase-3, caspase-8, and caspase-9 enzyme activity in the ΔsseK3 mutant group were significantly lower than in the WT group and sseK3-complemented groups, indicating that sseK3 could improve the caspase-3, caspase-8, and caspase-9 enzyme activity. We also found that there were no significant differences in pyruvic acid levels between the three groups, but the lactic acid level in the ΔsseK3 mutant group was much lower than that in the WT and sseK3-complemented groups. The ATP levels in the ΔsseK3 mutant group were remarkably higher than those in the WT and sseK3-complemented groups. These indicated that the sseK3 enhanced the level of glycolysis in macrophages infected by S. Typhimurium.Conclusions: S. Typhimurium sseK3 is likely involved in promoting macrophage apoptosis and modulating glycolysis in macrophages. Our results could improve our understanding of the relationship between apoptosis and glycolysis in macrophages induced by S. Typhimurium sseK3.

Salmonella enterica Serovar Typhimurium HtrA: regulation of expression and role of the chaperone and protease activities during infection

Microbiology ◽  
2009 ◽  
Vol 155 (3) ◽  
pp. 873-881 ◽  
Author(s):  
Claire Lewis ◽  
Henrieta Skovierova ◽  
Gary Rowley ◽  
Bronislava Rezuchova ◽  
Dagmar Homerova ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Protease Activity ◽  
Pdz Domain ◽  
Proximal Promoter ◽  
Wild Type ◽  
Regulation Of Expression ◽  
Serovar Typhimurium

HtrA is a bifunctional stress protein required by many bacterial pathogens to successfully cause infection. Salmonella enterica serovar Typhimurium (S. Typhimurium) htrA mutants are defective in intramacrophage survival and are highly attenuated in mice. Transcription of htrA in Escherichia coli is governed by a single promoter that is dependent on σ E (RpoE). S. Typhimurium htrA also possesses a σ E-dependent promoter; however, we found that the absence of σ E had little effect on production of HtrA by S. Typhimurium. This suggests that additional promoters control expression of htrA in S. Typhimurium. We identified three S. Typhimurium htrA promoters. Only the most proximal promoter, htrAp3, was σ E dependent. The other promoters, htrAp1 and htrAp2, are probably recognized by the principal sigma factor σ 70. These two promoters were constitutively expressed but were also slightly induced by heat shock. Thus expression of htrA is different in S. Typhimurium and E. coli. The role of HtrA is to deal with misfolded/damaged proteins in the periplasm. It can do this either by degrading (protease activity) or folding/capturing (chaperone/sequestering, C/S, activity) the aberrant protein. We investigated which of these functions are important to S. Typhimurium in vitro and in vivo. Point or deletion mutants of htrA that encode variant HtrA molecules have been used in previous studies to investigate the role of different regions of HtrA in C/S and protease activity. These htrA variants were placed under the control of the S. Typhimurium htrAP123 promoters and expressed in a S. Typhimurium htrA mutant, GVB1343. Both wild-type HtrA and HtrA (HtrA S210A) lacking protease activity enabled GVB1343 to grow at high temperature (46 °C). Both molecules also significantly enhanced the growth/survival of GVB1343 in the liver and spleen of mice during infection. However, expression of wild-type HtrA enabled GVB1343 to grow to much higher levels than expression of HtrA S210A. Thus both the protease and C/S functions of HtrA operate in vivo during infection but the protease function is probably more important. Absence of either PDZ domain completely abolished the ability of HtrA to complement the growth defects of GVB1343 in vitro or in vivo.

scholarly journals Gamma Irradiation or CD4+-T-Cell Depletion Causes Reactivation of Latent Salmonella enterica Serovar Typhimurium Infection in C3H/HeN Mice

2005 ◽  
Vol 73 (5) ◽  
pp. 2857-2862 ◽  
Author(s):  
Angela van Diepen ◽  
Joke S. van de Gevel ◽  
Margaretha M. Koudijs ◽  
Ferry Ossendorp ◽  
Henry Beekhuizen ◽  
...  
Keyword(s):  
T Cells ◽  
Salmonella Enterica ◽  
Primary Infection ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Secondary Infection ◽  
The Body ◽  
In Vivo Model ◽  
Serovar Typhimurium

ABSTRACT Upon infection with Salmonella, a host develops an immune response to limit bacterial growth and kill and eliminate the pathogen. Salmonella has evolved mechanisms to remain dormant within the body, only to reappear (reactivate) at a later time when the immune system is abated. We have developed an in vivo model for studying reactivation of Salmonella enterica serovar Typhimurium infection in mice. Upon subcutaneous infection, C3H/HeN (Ityr) mice showed an increase in bacterial numbers in livers and spleens, which reached a peak on day 19. After full recovery from the infection, these mice were irradiated or depleted of CD4+ T cells. The mice displayed a secondary infection peak in livers and spleens with a course similar to that of the primary infection. We concluded that CD4+ T cells are involved in active suppression of S. enterica serovar Typhimurium during latency. The role of CD4+ T cells during primary infection with S. enterica serovar Typhimurium is well established. This is the first study to describe a role of CD4+ T cells during the latent phase of S. enterica serovar Typhimurium infection.

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