Virulence determinants and the global regulation of virulence in Xanthomonas campestris.

2009 ◽  
pp. 211-230
Author(s):  
A. A. Vojnov ◽  
J. M. Dow ◽  
K. Bouarab
Keyword(s):  
Xanthomonas Campestris ◽  
Virulence Determinants ◽  
Global Regulation

scholarly journals Natural Genetic Variation of Xanthomonas campestris pv. campestris Pathogenicity on Arabidopsis Revealed by Association and Reverse Genetics

mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Endrick Guy ◽  
Anne Genissel ◽  
Ahmed Hajri ◽  
Matthieu Chabannes ◽  
Perrine David ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Genetic Basis ◽  
Reverse Genetics ◽  
Causal Agent ◽  
Aflp Markers ◽  
Avirulence Gene ◽  
Black Rot ◽  
Virulence Determinants ◽  
Content Type ◽  
Type Iii

ABSTRACTThe pathogenic bacteriumXanthomonas campestrispv. campestris, the causal agent of black rot of Brassicaceae, manipulates the physiology and the innate immunity of its hosts. Association genetic and reverse-genetic analyses of a world panel of 45X. campestrispv. campestris strains were used to gain understanding of the genetic basis of the bacterium’s pathogenicity toArabidopsis thaliana. We found that the compositions of the minimal predicted type III secretome varied extensively, with 18 to 28 proteins per strain. There were clear differences in aggressiveness of thoseX. campestrispv. campestris strains on twoArabidopsisnatural accessions. We identified 3 effector genes (xopAC,xopJ5, andxopAL2) and 67 amplified fragment length polymorphism (AFLP) markers that were associated with variations in disease symptoms. The nature and distribution of the AFLP markers remain to be determined, but we observed a low linkage disequilibrium level between predicted effectors and other significant markers, suggesting that additional genetic factors make a meaningful contribution to pathogenicity. Mutagenesis of type III effectors inX. campestrispv. campestris confirmed thatxopACfunctions as both a virulence and an avirulence gene inArabidopsisand thatxopAMfunctions as a second avirulence gene on plants of the Col-0 ecotype. However, we did not detect the effect of any other effector in theX. campestrispv. campestris 8004 strain, likely due to other genetic background effects. These results highlight the complex genetic basis of pathogenicity at the pathovar level and encourage us to challenge the agronomical relevance of some virulence determinants identified solely in model strains.IMPORTANCEThe identification and understanding of the genetic determinants of bacterial virulence are essential to be able to design efficient protection strategies for infected plants. The recent availability of genomic resources for a limited number of pathogen isolates and host genotypes has strongly biased our research toward genotype-specific approaches. Indeed, these do not consider the natural variation in both pathogens and hosts, so their applied relevance should be challenged. In our study, we exploited the genetic diversity ofXanthomonas campestrispv. campestris, the causal agent of black rot on Brassicaceae (e.g., cabbage), to mine for pathogenicity determinants. This work evidenced the contribution of known and unknown loci to pathogenicity relevant at the pathovar level and identified these virulence determinants as prime targets for breeding resistance toX. campestrispv. campestris in Brassicaceae.

Enterococcal Virulence Determinants In Urinary Tract Infection Patients

2012 ◽  
Vol 6 (1) ◽  
pp. 14-17
Author(s):  
Jabin Akhter ◽  
Shaheda Anwar ◽  
Sharmeen Ahmed
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Virulence Factors ◽  
Virulence Determinants ◽  
Microtitre Plate ◽  
Microbiological Method ◽  
Enterococcal Infection ◽  
Microtitre Plate Assay ◽  
Positive Frequency

Urinary tract infection caused by Enterococci has become frequent occurrences in health care settings. Currently they emerged with increasing resistance to multiple antibiotics.  Haemolysin, gelatinase and biofilm production are some markers that have been proposed as possible Enterococcal virulence factors. In view of the increasing importance of Enterococcal infection, the present study was designed to isolate and identify the Enterococci to the species level from urine of urinary tract infection patients and to investigate their possible virulence factors. Biofilm was detected on polystyrene microtitre plate to see the adherence of microorganism. Haemolysin production and gelatin hydrolysis detected by standard microbiological method. Fifty nine enterococcal isolates were speciated by conventional microbiological method and examined for their ability to form biofilm by microtitre plate assay. In this study, biofilm formations by Enterococci were found in 83.33% isolates from catheterized and 56.09% from non-catheterized patients. Aong them, E.faecalis & 50% E.faecium produced biofilm. About 43.63% E.faecalis & 10% E.faecium produced haemolysin and only one isolate were found to be gelatinase positive. Frequency of virulence factors (VFs) in combination was observed in this study. Two VFs (haemolysin and biofilm) were observed in 27.11% in combination and 3 VFs ( haemolysinm biofilm and gelatinase) were present in 1.69% isolates. These results suggest that although there may not be an absolute role for individual virulence determinants in infectivity, combinations of factors may play a role in allowing a biofilm infection to be more resistant to therapy.DOI: http://dx.doi.org/10.3329/bjmm.v6i1.19361 Bangladesh J Med Microbiol 2012; 06(01): 14-17

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