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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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Pathology of mice challenged with Y. pestis by small particle aerosol.A and B) HE stained skull sections of aerosol challenged mice. A) Mouse (2×) challenged with wild-type CO92 (6.9×105 CFU) that was moribund and euthanized on day 3 postchallenge. B) Mouse (4×) challenged with ΔtatA mutant (3.3×106 CFU) that was moribund and euthanized on day 7 postchallenge. No inner ear (IE) or meningeal involvement was detected for mice aerosol challenged with either strain of Y. pestis. HE stained lung sections (10×) of mice aerosol challenged with CO92 (C) or ΔtatA mutant (D). There was no difference in lesion character or severity in mice challenged with either strain.
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pone-0104524-g008: Pathology of mice challenged with Y. pestis by small particle aerosol.A and B) HE stained skull sections of aerosol challenged mice. A) Mouse (2×) challenged with wild-type CO92 (6.9×105 CFU) that was moribund and euthanized on day 3 postchallenge. B) Mouse (4×) challenged with ΔtatA mutant (3.3×106 CFU) that was moribund and euthanized on day 7 postchallenge. No inner ear (IE) or meningeal involvement was detected for mice aerosol challenged with either strain of Y. pestis. HE stained lung sections (10×) of mice aerosol challenged with CO92 (C) or ΔtatA mutant (D). There was no difference in lesion character or severity in mice challenged with either strain.

Mentions: To determine if the presence of Y. pestis bacteria within the inner ear was specific to exposure by the intranasal route, pathology samples were also examined from mice challenged by small particle aerosol with either the wild-type or mutant strain. In contrast to the observations with intranasal challenged mice (Fig. 7A–C), no inflammation or bacterial colonization was observed in the inner ear or meningeal areas for mice challenged via small-particle aerosol delivery for the Y. pestis strains (Figs. 8A and B). Additionally, lungs were examined from mice challenged by aerosol with each strain (Figs. 8C and D). Again, there was no difference in lung lesion characters or severity in mice challenged between strains.


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)

Pathology of mice challenged with Y. pestis by small particle aerosol.A and B) HE stained skull sections of aerosol challenged mice. A) Mouse (2×) challenged with wild-type CO92 (6.9×105 CFU) that was moribund and euthanized on day 3 postchallenge. B) Mouse (4×) challenged with ΔtatA mutant (3.3×106 CFU) that was moribund and euthanized on day 7 postchallenge. No inner ear (IE) or meningeal involvement was detected for mice aerosol challenged with either strain of Y. pestis. HE stained lung sections (10×) of mice aerosol challenged with CO92 (C) or ΔtatA mutant (D). There was no difference in lesion character or severity in mice challenged with either strain.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4125294&req=5

pone-0104524-g008: Pathology of mice challenged with Y. pestis by small particle aerosol.A and B) HE stained skull sections of aerosol challenged mice. A) Mouse (2×) challenged with wild-type CO92 (6.9×105 CFU) that was moribund and euthanized on day 3 postchallenge. B) Mouse (4×) challenged with ΔtatA mutant (3.3×106 CFU) that was moribund and euthanized on day 7 postchallenge. No inner ear (IE) or meningeal involvement was detected for mice aerosol challenged with either strain of Y. pestis. HE stained lung sections (10×) of mice aerosol challenged with CO92 (C) or ΔtatA mutant (D). There was no difference in lesion character or severity in mice challenged with either strain.
Mentions: To determine if the presence of Y. pestis bacteria within the inner ear was specific to exposure by the intranasal route, pathology samples were also examined from mice challenged by small particle aerosol with either the wild-type or mutant strain. In contrast to the observations with intranasal challenged mice (Fig. 7A–C), no inflammation or bacterial colonization was observed in the inner ear or meningeal areas for mice challenged via small-particle aerosol delivery for the Y. pestis strains (Figs. 8A and B). Additionally, lungs were examined from mice challenged by aerosol with each strain (Figs. 8C and D). Again, there was no difference in lung lesion characters or severity in mice challenged between strains.

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