RESUMO
Corynebacterium pseudotuberculosis is a facultative intracellular pathogen and the causative agent of several infectious and contagious chronic diseases, including caseous lymphadenitis, ulcerative lymphangitis, mastitis, and edematous skin disease, in a broad spectrum of hosts. In addition, Corynebacterium pseudotuberculosis infections pose a rising worldwide economic problem in ruminants. The complete genome sequences of 15 C. pseudotuberculosis strains isolated from different hosts and countries were comparatively analyzed using a pan-genomic strategy. Phylogenomic, pan-genomic, core genomic, and singleton analyses revealed close relationships among pathogenic corynebacteria, the clonal-like behavior of C. pseudotuberculosis and slow increases in the sizes of pan-genomes. According to extrapolations based on the pan-genomes, core genomes and singletons, the C. pseudotuberculosis biovar ovis shows a more clonal-like behavior than the C. pseudotuberculosis biovar equi. Most of the variable genes of the biovar ovis strains were acquired in a block through horizontal gene transfer and are highly conserved, whereas the biovar equi strains contain great variability, both intra- and inter-biovar, in the 16 detected pathogenicity islands (PAIs). With respect to the gene content of the PAIs, the most interesting finding is the high similarity of the pilus genes in the biovar ovis strains compared with the great variability of these genes in the biovar equi strains. Concluding, the polymerization of complete pilus structures in biovar ovis could be responsible for a remarkable ability of these strains to spread throughout host tissues and penetrate cells to live intracellularly, in contrast with the biovar equi, which rarely attacks visceral organs. Intracellularly, the biovar ovis strains are expected to have less contact with other organisms than the biovar equi strains, thereby explaining the significant clonal-like behavior of the biovar ovis strains.
Assuntos
Corynebacterium/genética , Genoma Bacteriano/genética , Animais , Deleção de Genes , Genes Bacterianos/genética , Variação Genética , Ilhas Genômicas/genética , Família Multigênica/genética , Especificidade da Espécie , Fatores de Virulência/genéticaRESUMO
The adaptability of pathogenic bacteria to hosts is influenced by the genomic plasticity of the bacteria, which can be increased by such mechanisms as horizontal gene transfer. Pathogenicity islands play a major role in this type of gene transfer because they are large, horizontally acquired regions that harbor clusters of virulence genes that mediate the adhesion, colonization, invasion, immune system evasion, and toxigenic properties of the acceptor organism. Currently, pathogenicity islands are mainly identified in silico based on various characteristic features: (1) deviations in codon usage, G+C content or dinucleotide frequency and (2) insertion sequences and/or tRNA genetic flanking regions together with transposase coding genes. Several computational techniques for identifying pathogenicity islands exist. However, most of these techniques are only directed at the detection of horizontally transferred genes and/or the absence of certain genomic regions of the pathogenic bacterium in closely related non-pathogenic species. Here, we present a novel software suite designed for the prediction of pathogenicity islands (pathogenicity island prediction software, or PIPS). In contrast to other existing tools, our approach is capable of utilizing multiple features for pathogenicity island detection in an integrative manner. We show that PIPS provides better accuracy than other available software packages. As an example, we used PIPS to study the veterinary pathogen Corynebacterium pseudotuberculosis, in which we identified seven putative pathogenicity islands.
Assuntos
Bactérias/genética , Bactérias/patogenicidade , Infecções Bacterianas/patologia , Ilhas Genômicas/genética , Software , Virulência/genética , Infecções Bacterianas/genética , Infecções Bacterianas/microbiologia , Biologia Computacional , Genoma BacterianoRESUMO
Although Corynebacterium diphtheriae has been classically described as an exclusively extracellular pathogen, there is growing evidence that it may be internalized by epithelial cells. The aim of the present report was to investigate the nature and involvement of the surface-exposed non-fimbrial 67-72 kDa proteins (67-72p), previously characterized as adhesin/hemagglutinin, in C. diphtheriae internalization by HEp-2 cells. Transmission electron microscopy and bacterial internalization inhibition assays indicated the role of 67-72p as invasin for strains of varied sources. Cytoskeletal changes with accumulation of polymerized actin in HEp-2 cells beneath adherent 67-72p-adsorbed microspheres were observed by the Fluorescent actin staining test. Trypan blue staining method and Methylthiazole tetrazolium reduction assay showed a significant decrease in viability of HEp-2 cells treated with 67-72p. Morphological changes in HEp-2 cells observed after treatment with 67-72p included vacuolization, nuclear fragmentation and the formation of apoptotic bodies. Flow cytometry revealed an apoptotic volume decrease in HEp-2 cells treated with 67-72p. Moreover, a double-staining assay using Propidium Iodide/Annexin V gave information about the numbers of vital vs. early apoptotic cells and late apoptotic or secondary necrotic cells. The comparative analysis of MALDI-TOF MS experiments with the probes provided for 67-72p CDC-E8392 with an in silico proteome deduced from the complete genome sequence of C. diphtheriae identified with significant scores 67-72p as the protein DIP0733. In conclusion, DIP0733 (67-72p) may be directly implicated in bacterial invasion and apoptosis of epithelial cells in the early stages of diphtheria and C. diphtheriae invasive infection.
Assuntos
Apoptose , Corynebacterium diphtheriae/patogenicidade , Endocitose , Hemaglutininas/metabolismo , Hepatócitos/microbiologia , Hepatócitos/fisiologia , Fatores de Virulência/metabolismo , Actinas/metabolismo , Linhagem Celular , Sobrevivência Celular , Corynebacterium diphtheriae/genética , Hemaglutininas/genética , Humanos , Multimerização Proteica , Fatores de Virulência/genéticaRESUMO
In this work, we report the complete genome sequence of a Corynebacterium pseudotuberculosis PAT10 isolate, collected from a lung abscess in an Argentine sheep in Patagonia, whose pathogen also required an investigation of its pathogenesis. Thus, the analysis of the genome sequence offers a means to better understanding of the molecular and genetic basis of virulence of this bacterium.
Assuntos
Infecções por Corynebacterium/veterinária , Corynebacterium pseudotuberculosis/genética , Genoma Bacteriano , Abscesso Pulmonar/microbiologia , Doenças dos Ovinos/microbiologia , Animais , Argentina , Sequência de Bases , Corynebacterium pseudotuberculosis/isolamento & purificação , Corynebacterium pseudotuberculosis/patogenicidade , Dados de Sequência Molecular , Ovinos , VirulênciaRESUMO
In this work, we report the whole-genome sequence of Corynebacterium pseudotuberculosis bv. equi strain CIP 52.97 (Collection Institut Pasteur), isolated in 1952 from a case of ulcerative lymphangitis in a Kenyan horse, which has evidently caused significant losses to agribusiness. Therefore, obtaining this genome will allow the detection of important targets for postgenomic studies, with the aim of minimizing problems caused by this microorganism.
Assuntos
Infecções por Corynebacterium/veterinária , Corynebacterium pseudotuberculosis/genética , Genoma Bacteriano , Doenças dos Cavalos/microbiologia , Animais , Sequência de Bases , Infecções por Corynebacterium/microbiologia , Corynebacterium pseudotuberculosis/isolamento & purificação , Cavalos , Quênia , Dados de Sequência MolecularRESUMO
BACKGROUND: Corynebacterium pseudotuberculosis, a gram-positive, facultative intracellular pathogen, is the etiologic agent of the disease known as caseous lymphadenitis (CL). CL mainly affects small ruminants, such as goats and sheep; it also causes infections in humans, though rarely. This species is distributed worldwide, but it has the most serious economic impact in Oceania, Africa and South America. Although C. pseudotuberculosis causes major health and productivity problems for livestock, little is known about the molecular basis of its pathogenicity. METHODOLOGY AND FINDINGS: We characterized two C. pseudotuberculosis genomes (Cp1002, isolated from goats; and CpC231, isolated from sheep). Analysis of the predicted genomes showed high similarity in genomic architecture, gene content and genetic order. When C. pseudotuberculosis was compared with other Corynebacterium species, it became evident that this pathogenic species has lost numerous genes, resulting in one of the smallest genomes in the genus. Other differences that could be part of the adaptation to pathogenicity include a lower GC content, of about 52%, and a reduced gene repertoire. The C. pseudotuberculosis genome also includes seven putative pathogenicity islands, which contain several classical virulence factors, including genes for fimbrial subunits, adhesion factors, iron uptake and secreted toxins. Additionally, all of the virulence factors in the islands have characteristics that indicate horizontal transfer. CONCLUSIONS: These particular genome characteristics of C. pseudotuberculosis, as well as its acquired virulence factors in pathogenicity islands, provide evidence of its lifestyle and of the pathogenicity pathways used by this pathogen in the infection process. All genomes cited in this study are available in the NCBI Genbank database (http://www.ncbi.nlm.nih.gov/genbank/) under accession numbers CP001809 and CP001829.
Assuntos
Corynebacterium pseudotuberculosis/patogenicidade , Evolução Molecular , Genoma Bacteriano , Virulência/genética , Corynebacterium pseudotuberculosis/genéticaRESUMO
This work reports the completion and annotation of the genome sequence of Corynebacterium pseudotuberculosis I19, isolated from an Israeli dairy cow with severe clinical mastitis. To present the whole-genome sequence, a de novo assembly approach using 33 million short (25-bp) mate-paired SOLiD reads only was applied. Furthermore, the automatic, functional, and manual annotations were attained with the use of several algorithms in a multistep process.