scholarly journals Generation and Characterization of a Defined Mutant of Streptococcus suis Lacking Suilysin

2001 ◽  
Vol 69 (4) ◽  
pp. 2732-2735 ◽  
Author(s):  
Andrew G. Allen ◽  
Steven Bolitho ◽  
Heather Lindsay ◽  
Shahid Khan ◽  
Clare Bryant ◽  
...  
Keyword(s):  
Parental Strain ◽  
Porcine Model ◽  
Systemic Infection ◽  
Streptococcus Suis ◽  
Infection Model ◽  
Gene Encoding ◽  
European Isolate ◽  
Mouse Infection Model ◽  
Allelic Replacement

ABSTRACT A defined allelic-replacement mutant of the sly gene, encoding a thiol-activated cytolysin, from a European isolate ofStreptococcus suis serotype 2 was generated and characterized. Unlike the parental strain, it is nonhemolytic, noncytotoxic for cultured macrophage-like cells, avirulent in a mouse infection model, yet only slightly attenuated in a porcine model of systemic infection.

scholarly journals Identification and Characterization of Di- and Tripeptide Transporter DtpT of Listeria monocytogenes EGD-e

2005 ◽  
Vol 71 (10) ◽  
pp. 5771-5778 ◽  
Author(s):  
Jeroen A. Wouters ◽  
Torsten Hain ◽  
Ajub Darji ◽  
Eric Hüfner ◽  
Henrike Wemekamp-Kamphuis ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Opportunistic Infections ◽  
Essential Amino Acids ◽  
Defined Medium ◽  
Infection Model ◽  
Intracellular Pathogen ◽  
Mouse Infection Model ◽  
Stress Protection ◽  
Identification And Characterization

ABSTRACT Listeria monocytogenes is a gram-positive intracellular pathogen responsible for opportunistic infections in humans and animals. Here we identified and characterized the dtpT gene (lmo0555) of L. monocytogenes EGD-e, encoding the di- and tripeptide transporter, and assessed its role in growth under various environmental conditions as well as in the virulence of L. monocytogenes. Uptake of the dipeptide Pro-[14C]Ala was mediated by the DtpT transporter and was abrogated in a ΔdtpT isogenic deletion mutant. The DtpT transporter was shown to be required for growth when the essential amino acids leucine and valine were supplied as peptides. The protective effect of glycine- and proline-containing peptides during growth in defined medium containing 3% NaCl was noted only in L. monocytogenes EGD-e, not in the ΔdtpT mutant strain, indicating that the DtpT transporter is involved in salt stress protection. Infection studies showed that DtpT contributes to pathogenesis in a mouse infection model but has no role in bacterial growth following infection of J774 macrophages. These studies reveal that DptT may contribute to the virulence of L. monocytogenes.

scholarly journals Contribution of the Major Secreted Yops of Yersinia enterocolitica O:8 to Pathogenicity in the Mouse Infection Model

2004 ◽  
Vol 72 (9) ◽  
pp. 5227-5234 ◽  
Author(s):  
Konrad Trülzsch ◽  
Thorsten Sporleder ◽  
Emeka I. Igwe ◽  
Holger Rüssmann ◽  
Jürgen Heesemann
Keyword(s):  
Small Intestine ◽  
Systemic Infection ◽  
Effector Proteins ◽  
Infection Model ◽  
Virulence Plasmid ◽  
The Novel ◽  
Serotype O ◽  
Mouse Infection Model ◽  
Mouse Tissues ◽  
First Time

ABSTRACT Pathogenic yersiniae (Yersinia pestis, Y. pseudotuberculosis, and Y. enterocolitica) harbor a 70-kb virulence plasmid (pYV) that encodes a type III secretion system and a set of at least six effector proteins (YopH, YopO, YopP, YopE, YopM, and YopT) that are injected into the host cell cytoplasm. Yops (Yersinia outer proteins) disturb the dynamics of the cytoskeleton, inhibit phagocytosis by macrophages, and downregulate the production of proinflammatory cytokines, which makes it possible for yersiniae to multiply extracellularly in lymphoid tissue. Y. enterocolitica serotype O:8 belongs to the highly mouse-pathogenic group of yersiniae in contrast to Y. enterocolitica serotype O:9. However, there has been no systematic study of the contribution of Yops to the pathogenicity of Y. enterocolitica O:8 in mice. We generated a set of yop gene deletion mutants of Y. enterocolitica O:8 by using the novel Red cloning procedure. We subsequently analyzed the contribution of yopH, -O, -P, -E, -M, -T, and -Q deletions to pathogenicity after oral and intravenous infection of mice. Here we showed for the first time that a ΔyopT deletion mutant colonizes mouse tissues to a greater extent than the parental strain. The ΔyopO, ΔyopP, and ΔyopE mutants were only slightly attenuated after oral infection since they were still able to colonize the spleen and liver and cause systemic infection. The ΔyopO mutant was lethal for mice, whereas ΔyopP and ΔyopE mutants were successfully eliminated from the spleen and liver 2 weeks after infection. In contrast the ΔyopH, ΔyopM, and ΔyopQ mutants were highly attenuated and not able to colonize the spleen and liver on any of the days tested. The ΔyopH, ΔyopO, ΔyopP, ΔyopE, ΔyopM, and ΔyopQ mutants had only modest defects in the colonization of the small intestine and Peyer's patches. The ΔyopE mutant was eliminated from the small intestine 3 weeks after infection, whereas the ΔyopH, ΔyopP, ΔyopM, and ΔyopQ mutants continued to colonize the small intestine at this time.

scholarly journals Insight Into the Virulence Related Secretion Systems, Fimbriae, and Toxins in O2:K1 Escherichia coli Isolated From Bovine Mastitis

2021 ◽  
Vol 8 ◽  
Author(s):  
Min Sun ◽  
Xing Gao ◽  
Kejie Zhao ◽  
Jiale Ma ◽  
Huochun Yao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bovine Mastitis ◽  
Systemic Infection ◽  
Infection Model ◽  
Secretion Systems ◽  
E Coli ◽  
Bacterial Pathogenicity ◽  
Mouse Infection Model ◽  
Type Iv ◽  
Mouse Infection

Mastitis remains a major infection of dairy cows and an important issue for the dairy farmers, and Escherichia coli (E. coli) bovine mastitis is a disease of significant economic importance in the dairy industry. Our study identified six isolates belong to phylogroup B2 from 69 bovine mastitis E. coli strains. Except for one serotype O1 strain, all group B2 isolates were identified into serotype O2 and showed significantly higher mortality in the mouse infection than other phylogroups' strains. Genomic analyses and further tests were performed to examine the role of secretion systems, fimbriae, and toxins during the systemic infection of O2:K1 strain BCE049. Two integral T6SS loci and three predicted effectors clusters were found to assemble the functional T6SS complex and deliver diverse toxic effectors to modulate bacterial virulence in the mouse infection model. A total of four T4SS loci were harbored in the BCE049 genome, three of them are encoded in different plasmids, respectively, whereas the last one locates within the bacterial chromosome at FQU84_16715 to FQU84_16760, and was significantly involved in the bacterial pathogenicity. Numerous predicted pilus biosynthesis gene loci were found in the BCE049 genome, whereas most of them lost long fragments encoding key genes for the pili assembly. Unexpectedly, a type IV pilus gene locus locating at FQU84_01405 to FQU84_01335 in the plasmid 2, was found to be required for the full virulence of mastitis strain BCE049. It should be noted that a genetic neighborhood inserted with diverse genes is encoded by the plasmid 1, which harbors three prominent toxins including β-hemolysin, cytotoxic necrotizing factor 2 and cytolethal distending toxin type III. Consequent studies verified that these toxins significantly contributed to the bacterial pathogenicity. These findings provide a molecular blueprint for understanding the underlying mechanisms employed by the bovine mastitis E. coli to colonize in host and cause systemic infection.

scholarly journals In Vitro and In Vivo Activities of SCH 56592 (Posaconazole), a New Triazole Antifungal Agent, againstAspergillus and Candida

2000 ◽  
Vol 44 (8) ◽  
pp. 2017-2022 ◽  
Author(s):  
Anthony Cacciapuoti ◽  
David Loebenberg ◽  
Erik Corcoran ◽  
Fred Menzel ◽  
Eugene L. Moss ◽  
...  
Keyword(s):  
Body Weight ◽  
Antifungal Agent ◽  
Systemic Infection ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Immunocompromised Mouse ◽  
Excellent Activity ◽  
Dose Dependent

ABSTRACT SCH 56592 (posaconazole), a new triazole antifungal agent, was tested in vitro, and its activity was compared to that of itraconazole against 39 Aspergillus strains and to that of fluconazole against 275 Candida and 9 Cryptococcus strains. The SCH 56592 MICs for Aspergillus ranged from ≤0.002 to 0.5 μg/ml, and those of itraconazole ranged from ≤0.008 to 1 μg/ml. The SCH 56592 MICs for Candida andCryptococcus strains ranged from ≤0.004 to 16 μg/ml, and those of fluconazole ranged from ≤0.062 to >64 μg/ml. SCH 56592 showed excellent activity against Aspergillus fumigatus andAspergillus flavus in a pulmonary mouse infection model. When administered therapeutically, the 50% protective doses (PD50s) of SCH 56592 ranged from 3.6 to 29.9 mg/kg of body weight, while the PD50s of SCH 56592 administered prophylactically ranged from 0.9 to 9.0 mg/kg; itraconazole administered prophylactically was ineffective (PD50s, >75 mg/kg). SCH 56592 was also very efficacious against fluconazole-susceptible, -susceptible dose-dependent, or -resistantCandida albicans strains in immunocompetent or immunocompromised mouse models of systemic infection. The PD50s of SCH 56592 administered therapeutically ranged from 0.04 to 15.6 mg/kg, while the PD50s of SCH 56592 administered prophylactically ranged from 1.5 to 19.4 mg/kg. SCH 56592 has excellent potential for therapy against seriousAspergillus or Candida infections.

Characterization of a virulence-associated and cell-wall-located DNase of Streptococcus pyogenes

Microbiology ◽  
2010 ◽  
Vol 156 (1) ◽  
pp. 184-190 ◽  
Author(s):  
Tadao Hasegawa ◽  
Masaaki Minami ◽  
Akira Okamoto ◽  
Ichiro Tatsuno ◽  
Masanori Isaka ◽  
...  
Keyword(s):  
Cell Wall ◽  
Streptococcus Pyogenes ◽  
Protein A ◽  
Insoluble Fraction ◽  
Infection Model ◽  
Two Dimensional Gel Electrophoresis ◽  
Mouse Infection Model ◽  
Peptide Mass ◽  
A Cell

We investigated culture supernatant proteins from the M1 serotype of Streptococcus pyogenes by two-dimensional gel electrophoresis and peptide mass mapping analysis, and characterized the single protein spots. Among them, we analysed the Spy0747 protein. This protein is homologous to the SsnA protein, a cell-wall-located DNase expressed in Streptococcus suis serotype 2. We designated the Spy0747 protein as SpnA. SpnA protein was also detected in the insoluble fraction of whole-cell lysates using shotgun proteomic analysis, suggesting that SpnA is also located in the cell wall. SpnA was expressed as a glutathione S-transferase-fusion protein in Escherichia coli. We confirmed that the recombinant protein had DNase activity that was dependent on Ca2+ and Mg2+, like SsnA. Blood bactericidal assays and mouse infection model experiments showed that the spnA knockout strain was less virulent than the parental strain, thus suggesting that SpnA could play an important role in virulence. Using PCR, we found that the spnA gene was present in all clinical S. pyogenes strains we examined. Our results, together with a previous report identifying Spy0747 as a surface-associated protein, suggest that SpnA is an important cell-wall-located DNase that is generally produced in S. pyogenes and is involved in virulence.

scholarly journals SpyA, a C3-Like ADP-Ribosyltransferase, Contributes to Virulence in a Mouse Subcutaneous Model of Streptococcus pyogenes Infection

2011 ◽  
Vol 79 (6) ◽  
pp. 2404-2411 ◽  
Author(s):  
Jessica S. Hoff ◽  
Mark DeWald ◽  
Steve L. Moseley ◽  
Carleen M. Collins ◽  
Jovanka M. Voyich
Keyword(s):  
Streptococcus Pyogenes ◽  
Lesion Size ◽  
Infected Tissue ◽  
Infection Model ◽  
Mrna Levels ◽  
Wild Type ◽  
Gene Encoding ◽  
Content Type ◽  
Mouse Infection Model ◽  
Adp Ribosyltransferase

ABSTRACTStreptococcus pyogenesis an important human pathogen with an expansive repertoire of verified and putative virulence factors. Here we demonstrate that a mutant deficient in the production of the streptococcal ADP-ribosyltransferase SpyA generates lesions of reduced size in a subcutaneous mouse infection model. At early stages of infection, when the difference in lesion size is first established, inflamed tissue isolated from lesions of mice infected withspyAmutant bacteria has higher levels of mRNA encoding the chemokines CXCL1 and CCL2 than does tissue isolated from mice infected with wild-type bacteria. In addition, at these early times, the mRNA levels for the gene encoding the intermediate filament vimentin are higher in the mutant-infected tissue. As wound resolution progresses, mRNA levels of the gene encoding matrix metallopeptidase 2 are lower in mutant-infected tissue. Furthermore, we demonstrate that thespyAmutant is internalized more efficiently than wild-type bacteria by HeLa cells. We conclude that SpyA contributes to streptococcal pathogenesis in the mouse subcutaneous infection model. Our observations suggest that the presence of SpyA delays wound healing in this model.

scholarly journals Contribution of Fibronectin-Binding Protein to Pathogenesis of Streptococcus suis Serotype 2

2002 ◽  
Vol 70 (3) ◽  
pp. 1319-1325 ◽  
Author(s):  
Astrid de Greeff ◽  
Herma Buys ◽  
Robin Verhaar ◽  
Janny Dijkstra ◽  
Loek van Alphen ◽  
...  
Keyword(s):  
Binding Protein ◽  
Streptococcus Suis ◽  
Infection Model ◽  
Organ Cultures ◽  
Gene Encoding ◽  
E Coli ◽  
Mutant Strains ◽  
Fibronectin Binding Protein ◽  
Suis Serotype

ABSTRACT In the present study we investigated the role of the fibronectin (FN)- and fibrinogen (FGN)-binding protein (FBPS) in the pathogenesis of Streptococcus suis serotype 2 in piglets. The complete gene encoding FBPS from S. suis serotype 2 was cloned in Escherichia coli and sequenced. The occurrence of the gene in various serotypes was analyzed by hybridization studies. The FBPS protein was expressed in E. coli and purified, and binding to human FN and FGN was demonstrated. The induction of antibodies in piglets was studied upon infection. An isogenic mutant unable to produce FBPS was constructed, and the levels of virulence of the wild-type and mutant strains were compared in a competitive infection model in young piglets. Organ cultures showed that FBPS was not required for colonization of the tonsils but that FBPS played a role in the colonization of the specific organs involved in an S. suis infection. Therefore, the FBPS mutant was considered as an attenuated mutant.

scholarly journals Silencing and Reactivation of Urease inYersinia pestis Is Determined by One G Residue at a Specific Position in the ureD Gene

2001 ◽  
Vol 69 (1) ◽  
pp. 170-176 ◽  
Author(s):  
Florent Sebbane ◽  
Annie Devalckenaere ◽  
Jeannine Foulon ◽  
Elisabeth Carniel ◽  
Michel Simonet
Keyword(s):  
Parental Strain ◽  
Urease Activity ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Lethal Infection ◽  
Specific Position ◽  
Species Specific

ABSTRACT Yersinia pestis, the plague agent, is a naturally nonureolytic microorganism, while all other Yersiniaspecies display a potent urease activity. In this report we demonstrate that Y. pestis harbors a complete urease locus composed of three structural (ureABC) and four accessory (ureEFGD) genes. Absence of ureolytic activity is due to the presence of one additional G residue in a poly(G) stretch, which introduces a premature stop codon in ureD. The presence of the same additional G in eight other Y. pestis isolates indicates that this mutation is species specific. Spontaneous excision of the extra G occurs at a frequency of 10−4 to 10−5 and restores a ureolytic phenotype to Y. pestis. The virulence of two independent ureolytic clones ofY. pestis injected either intravenously, subcutaneously, or intragastrically did not differ from that of the parental strain in the mouse infection model. Coinfection experiments with an equal number of ureolytic and nonureolytic bacteria did not evidence any difference in the ability of the two variants to multiply in vivo and to cause a lethal infection. Altogether our results demonstrate that variation of one extra G residue in ureD determines the ureolytic activity of Y. pestis but does not affect its virulence for mice or its ability to multiply and disseminate.

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