Browsing by Author "Azevedo, Vasco"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Comparative genomic analysis between Corynebacterium pseudotuberculosis strains isolated from buffalo
    Canario Viana, Marcus Vinicius; Figueiredo, Henrique; Ramos, Rommel; Guimaraes, Luis Carlos; Pereira, Felipe Luiz; Dorella, Fernanda Alves; Selim, Salah Abdel Karim; Salaheldean, Mohammad; Silva, Artur; Wattam, Alice R.; Azevedo, Vasco (PLOS, 2017-04-26)
    Corynebacterium pseudotuberculosis is a Gram-positive, pleomorphic, facultative intracellular pathogen that causes Oedematous Skin Disease (OSD) in buffalo. To better understand the pathogenic mechanisms of OSD, we performed a comparative genomic analysis of 11 strains of C. pseudotuberculosis isolated from different buffalo found to be infected in Egypt during an outbreak that occurred in 2008. Sixteen previously described pathogenicity islands (PiCp) were present in all of the new buffalo strains, but one of them, PiCp12, had an insertion that contained both a corynephage and a diphtheria toxin gene, both of which may play a role in the adaptation of C. pseudotuberculosis to this new host. Synteny analysis showed variations in the site of insertion of the corynephage during the same outbreak. A gene functional comparison showed the presence of a nitrate reductase operon that included genes involved in molybdenum cofactor biosynthesis, which is necessary for a positive nitrate reductase phenotype and is a possible adaptation for intracellular survival. Genomes from the buffalo strains also had fusions in minor pilin genes in the spaA and spaD gene cluster (spaCX and spaYEF), which could suggest either an adaptation to this particular host, or mutation events in the immediate ancestor before this particular epidemic. A phylogenomic analysis confirmed a clear separation between the Ovis and Equi biovars, but also showed what appears to be a clustering by host species within the Equi strains.
  • Thumbnail Image
    Comparative mangrove metagenome reveals global prevalence of heavy metals and antibiotic resistome across different ecosystems
    Imchen, Madangchanok; Kumavath, Ranjith; Barh, Debmalya; Vaz, Aline; Goes-Neto, Aristoteles; Tiwari, Sandeep; Ghosh, Preetam; Wattam, Alice R.; Azevedo, Vasco (Springer Nature, 2018-07-25)
    The mangrove ecosystem harbors a complex microbial community that plays crucial role in biogeochemical cycles. In this study, we analyzed mangrove sediments from India using de novo whole metagenome next generation sequencing (NGS) and compared their taxonomic and functional community structures to mangrove metagenomics samples from Brazil and Saudi Arabia. The most abundant phyla in the mangroves of all three countries was Proteobacteria, followed by Firmicutes and Bacteroidetes. A total of 1,942 genes were found to be common across all the mangrove sediments from each of the three countries. The mangrove resistome consistently showed high resistance to fluoroquinolone and acriflavine. A comparative study of the mangrove resistome with other ecosystems shows a higher frequency of heavy metal resistance in mangrove and terrestrial samples. Ocean samples had a higher abundance of drug resistance genes with fluoroquinolone and methicillin resistance genes being as high as 28.178% +/- 3.619 and 10.776% +/- 1.823. Genes involved in cobalt-zinc-cadmium resistance were higher in the mangrove (23.495% +/- 4.701) and terrestrial (27.479% +/- 4.605) ecosystems. Our comparative analysis of samples collected from a variety of habitats shows that genes involved in resistance to both heavy metals and antibiotics are ubiquitous, irrespective of the ecosystem examined.
  • Thumbnail Image
    Genome Sequences of Three Brucella canis Strains Isolated from Humans and a Dog
    Canario Viana, Marcus Vinicius; Wattam, Alice Rebecca; Batra, Dhwani Govil; Boisvert, Sebastien; Brettin, Thomas Scott; Frace, Michael; Xia, Fangfang; Azevedo, Vasco; Tiller, Rebekah; Hoffmaster, Alex R. (2017-02)
    Brucella canis is a facultative intracellular pathogen that preferentially infects members of the Canidae family. Here, we report the genome sequencing of two Brucella canis strains isolated from humans and one isolated from a dog host.
  • Thumbnail Image
    Rapidly evolving changes and gene loss associated with host switching in Corynebacterium pseudotuberculosis
    Canario Viana, Marcus Vinicius; Sahm, Arne; Goes Neto, Aristoteles; Pereira Figueiredo, Henrique Cesar; Wattam, Alice Rebecca; Azevedo, Vasco (PLOS, 2018-11-12)
    Phylogenomics and genome scale positive selection analyses were performed on 29 Corynebacterium pseudotuberculosis genomes that were isolated from different hosts, including representatives of the Ovis and Equi biovars. A total of 27 genes were identified as undergoing adaptive changes. An analysis of the clades within this species and these biovars, the genes specific to each branch, and the genes responding to selective pressure show clear differences, indicating that adaptation and specialization is occurring in different clades. These changes are often correlated with the isolation host but could indicate responses to some undetermined factor in the respective niches. The fact that some of these more-rapidly evolving genes have homology to known virulence factors, antimicrobial resistance genes and drug targets shows that this type of analysis could be used to identify novel targets, and that these could be used as a way to control this pathogen.