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A Yersinia pestis tat mutant is attenuated in bubonic and small-aerosol pneumonic challenge models of infection but not as attenuated by intranasal challenge.

Bozue J, Cote CK, Chance T, Kugelman J, Kern SJ, Kijek TK, Jenkins A, Mou S, Moody K, Fritz D, Robinson CG, Bell T, Worsham P - PLoS ONE (2014)

Bottom Line: Deletion of the tatA gene resulted in several consequences for the mutant as compared to wild-type.In contrast, when mice were challenged intranasally with the mutant, very little difference in the LD50 was observed between wild-type and mutant strains.Collectively, these findings demonstrate an essential role for the Tat pathway in the virulence of Y. pestis in bubonic and small-aerosol pneumonic infection but less important role for intranasal challenge.

View Article: PubMed Central - PubMed

Affiliation: Bacteriology Division, The United States Army of Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America.

ABSTRACT
Bacterial proteins destined for the Tat pathway are folded before crossing the inner membrane and are typically identified by an N-terminal signal peptide containing a twin arginine motif. Translocation by the Tat pathway is dependent on the products of genes which encode proteins possessing the binding site of the signal peptide and mediating the actual translocation event. In the fully virulent CO92 strain of Yersinia pestis, the tatA gene was deleted. The mutant was assayed for loss of virulence through various in vitro and in vivo assays. Deletion of the tatA gene resulted in several consequences for the mutant as compared to wild-type. Cell morphology of the mutant bacteria was altered and demonstrated a more elongated form. In addition, while cultures of the mutant strain were able to produce a biofilm, we observed a loss of adhesion of the mutant biofilm structure compared to the biofilm produced by the wild-type strain. Immuno-electron microscopy revealed a partial disruption of the F1 antigen on the surface of the mutant. The virulence of the ΔtatA mutant was assessed in various murine models of plague. The mutant was severely attenuated in the bubonic model with full virulence restored by complementation with the native gene. After small-particle aerosol challenge in a pneumonic model of infection, the mutant was also shown to be attenuated. In contrast, when mice were challenged intranasally with the mutant, very little difference in the LD50 was observed between wild-type and mutant strains. However, an increased time-to-death and delay in bacterial dissemination was observed in mice infected with the ΔtatA mutant as compared to the parent strain. Collectively, these findings demonstrate an essential role for the Tat pathway in the virulence of Y. pestis in bubonic and small-aerosol pneumonic infection but less important role for intranasal challenge.

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Adherence of Y. pestis biofilm.The Y. pestis A) wild-type CO92 and B) ΔtatA mutant cultures were grown in HI broth at 26°C. Arrows indicate biofilm formation. C) To measure biofilm adherence, the biofilm of wild-type CO92, ΔtatA mutant, and complemented ΔtatA mutant was stained with crystal violet and assayed by absorbance as described in the Materials and Methods. The standard deviation was derived from quadruplicate samples. These data represent three separate experiments.
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pone-0104524-g003: Adherence of Y. pestis biofilm.The Y. pestis A) wild-type CO92 and B) ΔtatA mutant cultures were grown in HI broth at 26°C. Arrows indicate biofilm formation. C) To measure biofilm adherence, the biofilm of wild-type CO92, ΔtatA mutant, and complemented ΔtatA mutant was stained with crystal violet and assayed by absorbance as described in the Materials and Methods. The standard deviation was derived from quadruplicate samples. These data represent three separate experiments.

Mentions: In addition to the structural differences observed with the ΔtatA strain, the mutant also demonstrated a defect in biofilm integrity. After overnight growth at 26°C, a bacterial biofilm formed for both the Y. pestis wild-type (Fig. 3A) and mutant (Fig. 3B) cultures at the liquid/air interface. The biofilm, however, of the ΔtatA cultures was easily dislodged as compared to the wild-type strain.


A Yersinia pestis tat mutant is attenuated in bubonic and small-aerosol pneumonic challenge models of infection but not as attenuated by intranasal challenge.

Bozue J, Cote CK, Chance T, Kugelman J, Kern SJ, Kijek TK, Jenkins A, Mou S, Moody K, Fritz D, Robinson CG, Bell T, Worsham P - PLoS ONE (2014)

Adherence of Y. pestis biofilm.The Y. pestis A) wild-type CO92 and B) ΔtatA mutant cultures were grown in HI broth at 26°C. Arrows indicate biofilm formation. C) To measure biofilm adherence, the biofilm of wild-type CO92, ΔtatA mutant, and complemented ΔtatA mutant was stained with crystal violet and assayed by absorbance as described in the Materials and Methods. The standard deviation was derived from quadruplicate samples. These data represent three separate experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4125294&req=5

pone-0104524-g003: Adherence of Y. pestis biofilm.The Y. pestis A) wild-type CO92 and B) ΔtatA mutant cultures were grown in HI broth at 26°C. Arrows indicate biofilm formation. C) To measure biofilm adherence, the biofilm of wild-type CO92, ΔtatA mutant, and complemented ΔtatA mutant was stained with crystal violet and assayed by absorbance as described in the Materials and Methods. The standard deviation was derived from quadruplicate samples. These data represent three separate experiments.
Mentions: In addition to the structural differences observed with the ΔtatA strain, the mutant also demonstrated a defect in biofilm integrity. After overnight growth at 26°C, a bacterial biofilm formed for both the Y. pestis wild-type (Fig. 3A) and mutant (Fig. 3B) cultures at the liquid/air interface. The biofilm, however, of the ΔtatA cultures was easily dislodged as compared to the wild-type strain.

Bottom Line: Deletion of the tatA gene resulted in several consequences for the mutant as compared to wild-type.In contrast, when mice were challenged intranasally with the mutant, very little difference in the LD50 was observed between wild-type and mutant strains.Collectively, these findings demonstrate an essential role for the Tat pathway in the virulence of Y. pestis in bubonic and small-aerosol pneumonic infection but less important role for intranasal challenge.

View Article: PubMed Central - PubMed

Affiliation: Bacteriology Division, The United States Army of Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America.

ABSTRACT
Bacterial proteins destined for the Tat pathway are folded before crossing the inner membrane and are typically identified by an N-terminal signal peptide containing a twin arginine motif. Translocation by the Tat pathway is dependent on the products of genes which encode proteins possessing the binding site of the signal peptide and mediating the actual translocation event. In the fully virulent CO92 strain of Yersinia pestis, the tatA gene was deleted. The mutant was assayed for loss of virulence through various in vitro and in vivo assays. Deletion of the tatA gene resulted in several consequences for the mutant as compared to wild-type. Cell morphology of the mutant bacteria was altered and demonstrated a more elongated form. In addition, while cultures of the mutant strain were able to produce a biofilm, we observed a loss of adhesion of the mutant biofilm structure compared to the biofilm produced by the wild-type strain. Immuno-electron microscopy revealed a partial disruption of the F1 antigen on the surface of the mutant. The virulence of the ΔtatA mutant was assessed in various murine models of plague. The mutant was severely attenuated in the bubonic model with full virulence restored by complementation with the native gene. After small-particle aerosol challenge in a pneumonic model of infection, the mutant was also shown to be attenuated. In contrast, when mice were challenged intranasally with the mutant, very little difference in the LD50 was observed between wild-type and mutant strains. However, an increased time-to-death and delay in bacterial dissemination was observed in mice infected with the ΔtatA mutant as compared to the parent strain. Collectively, these findings demonstrate an essential role for the Tat pathway in the virulence of Y. pestis in bubonic and small-aerosol pneumonic infection but less important role for intranasal challenge.

Show MeSH
Related in: MedlinePlus