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- Immune Response Induced by ppGpp-Defective Salmonella enterica serovar Gallinarum in Chickens
- Sang-Ik Park , Jae-Ho Jeong , Hyon E. Choy , Joon Haeng Rhee , Hee-Sam Na , Tae-Hoon Lee , Moon Her , Kyoung-Oh Cho , Yeongjin Hong
- J. Microbiol. 2010;48(5):674-681. Published online November 3, 2010
- DOI: https://doi.org/10.1007/s12275-010-0179-6
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- 17 Scopus
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Abstract
- To protect chickens from typhoid caused by Salmonella enterica serovar Gallinarum (S. Gallinarum), the attenuated 9R strain has been used in the field as a vaccine. However, safety concerns have been raised because the mutations in 9R are undefined while its efficacy is still a question under debate. A global regulator, ppGpp, synthesized by RelA and SpoT, has been shown to induce various virulence genes in S. Gallinarum (Jeong et al., 2008). In this study, two mutant strains defective in ppGpp-synthesis were constructed in wild-type S. Gallinarum (∆ppGpp) and 9R strain (9R-∆ppGpp) backgrounds and tested as live vaccines in chickens. After oral inoculation, the LD50 values of ∆ppGpp and 9R-∆ppGpp were approximately 5×1010 colony forming unit (CFU) similarly as 9R strain, which was ~105-fold higher than that of the wildtype S. Gallinarum strain. Immunological analyses revealed immunization with either of the two attenuated ppGpp-defective strains induced significant antibody responses, the production of antibody-secreting B cells in blood, proliferation of CD4+ and CD8+ T cells in the spleen, and splenic expression of proinflammatory cytokines, such as IFN-γ and TGF-β4, at levels comparable to the 9R strain. Chickens immunized with the mutants (1×108 CFU) were 80% protected against oral challenge with 1×109 wild-type virulent bacteria (4,000-fold LD50 dose), similar to the level of protection achieved by 9R immunization. Based on these data, live attenuated ∆ppGpp-defective strains may serve as novel vaccines to control fowl typhoid in chickens.
- ppGpp-Mediated Stationary Phase Induction of the Genes Encoded by Horizontally Acquired Pathogenicity Islands and cob/pdu Locus in Salmonella enterica serovar Typhimurium
- Miryoung Song , Hyun-Ju Kim , Sangryeol Ryu , Hyunjin Yoon , Jiae Yun , Hyon E. Choy
- J. Microbiol. 2010;48(1):89-95. Published online March 11, 2010
- DOI: https://doi.org/10.1007/s12275-009-0179-6
- 39 View
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- 16 Scopus
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Abstract
- Salmonella enterica is highly diverse in terms of genome structure, which is at least partly due to the horizontal transfer of genetic elements from various sources. In this study, we examined the expression profiles of such genes in Salmonella Pathogenicity Islands (SPIs) and the cob/pdu locus, horizontally acquired large DNA segments, during growth under standard growth conditions. Transcripts from exponentially growing and early stationary phase Salmonellae were compared using various methods including cDNA microarray analysis. Nearly all genes encoded by SPIs and the cob/pdu locus were induced at the onset of the stationary phase in a stringent molecule ppGpp-dependent but stationary phase σ, σ38-independent manner. Although, it has been suggested that ppGpp acts in concert with DksA, we found the stationary phase induction of those SPI genes was not DksA dependent. It is suggested that ppGpp stimulates the expression of these stress-inducible genes encoded by horizontally acquired DNA, by itself or in concert with DksA.
- Initial Characterization of yliH in Salmonella typhimurium
- Kyung-Hwa Park , Miryung Song , Hyon E. Choy
- J. Microbiol. 2007;45(6):558-565.
- DOI: https://doi.org/2608 [pii]
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Abstract
- Using microarray analysis, we determined those Salmonella genes induced at the entry of stationary phase, and subsequently discovered that uncharacterized yliH was induced most dramatically. We set out to establish the molecular mechanism underlying the stationary phase induction of yliH under the standard culture condition, LB with vigorous aeration, by analyzing its promoter activity in various mutant backgrounds, lacking stationary phase σ, RpoS-, or stringent signal molecules ppGpp, ΔrelA ΔspoT. It was found that the stationary phase induction of yliHp was partially dependent on rpoS but entirely dependent on ppGpp. DNA sequence analysis revealed that the Salmonella yliH gene is composed of 381 base-pair nucleotides, with overall amino acid sequence revealing 76.38% amino acid identity and 88.98% similarity with Escherichia coli yliH, although no motif from data base was noted for its possible role. Recently however, it has been reported that yliH in E. coli was implicated in biofilm formation and motility by repressing these activities (Domka et al., 2006). We have constructed a mutant Salmonella deleting yliH gene by allele replacement and examined its phenotype, and found that the yliH in Salmonella more or less affects motility and adherence by enhancing these activities. The effect on biofilm formation in Salmonella was uncertain. Moreover, addition of cloned yliH of E. coli into Salmonella did not reduce motility or adherence. Taken together, it appears that the pathways implicating yliH for biofilm formation and motility in E. coli and in Salmonella are somewhat different.
Review
- ppGpp: Stringent Response and Survival
- Vikas Jain , Manish Kumar , Dipankar Chatterji
- J. Microbiol. 2006;44(1):1-10.
- DOI: https://doi.org/2343 [pii]
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Abstract
- Adaptation to any undesirable change in the environment dictates the survivability of many microorganisms, with such changes generating a quick and suitable response, which guides the physiology of bacteria. During nutritional deprivation, bacteria show a stringent response, as characterized by the accumulation of (p)ppGpp, resulting in the repression of stable RNA species, such as rRNA and tRNA, with a concomitant change in colony morphology. However, genes involved in amino acid biosynthesis become over-expressed to help bacteria survive under such conditions. The survivability of pathogenic bacteria inside a host cell also depends upon the stringent response demonstrated. Therefore, an understanding of the physiology of stringent conditions becomes very interesting in regulation of the growth and persistence of such invading pathogens.
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