infections [ 7 ]. The staphylococcal virulence factors are mostly encoded by genetic elements such as prophages, transposons, plasmids, and pathogenicity islands [ 8 ]. Most likely due to horizontal transfer, these mobile elements are not found
variety of virulence factors that play an important role in a wide range of pathogenic mechanisms, such as adhesion, invasion, intracellular survival, toxin production, and iron acquisition [ 7 ]. However, the presence of virulence genes in multidrug
ability of GAS to cause invasive-systemic infections, as well as local tissue infections, is because it has a large number of virulence factors, such as M protein, pyrogenic exotoxins, capsule, streptolysin O and S, F protein, streptokinase, DNase [ 1
Introduction Francisella tularensis is a Gram negative bacterium that causes the disease tularemia. One of the important F. tularensis proteins critical for its virulence is the conserved lipoprotein DsbA (gene
Afshari, F. 2008. Identification of virulence factors of Puccinia triticina , the casual agent of wheat leaf rust in Iran. Proc.11 th Int. Wheat Genet. Symp., http://hdl.handle.net/2123
concern. Pathogenic E. coli can cause either enteric or extraintestinal disease through the acquisition of several virulence genes. In dogs, two main pathotypes have been associated with enteric disease: enterotoxigenic E. coli (ETEC) and attaching and
Evolution of pathogenicity, morphological, and genetic traits were analyzed in a local Plasmopara halstedii (downy mildew) population (including two parental and five progeny isolates) multiplied under sunflower qualitative resistance selection pressure for five years. The two components of pathogenicity developed in response to Pl resistance genes selection pressure. The emergence of new virulence in P. halstedii progeny isolates carrying several levels of aggressiveness was an important consequence of selection pressure. However, appearance of new virulence did get along with evolution of aggressiveness in progeny isolates as compared with parental ones. For progeny P. halstedii isolates, an increase in pathogen virulence had direct consequences on its aggressiveness. There was no influence of selection pressure on morphological traits, but an effect was observed on evolution of genetic architecture. However, arrangement of genetic traits did get along with evolution of pathogenicity. It is clear that qualitative resistance selection pressure plays an important role in the evolution of sunflower downy mildew population.
Miller 1999 A new pathway for the secretion of virulence factors by bacteria: The flagellar export apparatus functions as a protein-secretion system Proc Natl Acad Sci U S A
Pathogenicity including virulence and aggressiveness characteristics was studied on three Plasmopara halstedii (the causal agent of downy mildew) isolates of races 710, 714 and 704 using five single zoosporangium isolates per pathogen isolate. Based on the reaction for the P. halstedii isolates to four sunflower hybrids H1 to H4 varying only in their downy mildew resistance genes, there were differences in virulence spectrum in pathogen isolates. Analysis of five single zoosporangium isolates for P. halstedii isolates showed significant variability within pathogen isolate for all aggressiveness criteria. There were no significant differences among pathogen isolates for all aggressiveness criteria. There were significant differences in the morphology of zoosporangia and sporangiophores for pathogen isolates. Genetic relationships were detected between pathogen isolates using 12 EST-derived markers. There was no intra-race genetic variation, but three genetically-identified groups were detected among pathogen isolates.
. coli (ExPEC) strains possess various virulence traits and the most important ones are adhesins (P fimbriae, S fimbriae, F1C fimbriae, G fimbriae, Dr antigen-specific adhesins, type 1 fimbriae, blood group M-specific adhesin and iron regulated gene