Examinando por Autor "Bethke, J."

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    Biochemical, serological, and genetic characterisation of Renibacterium salmoninarum isolates recovered from salmonids in Chile
    (FRS Marine Laboratory, 2017) Bethke, J.; Quezada, J.; Poblete-Morales, M.; Irgang, R.; Yáňez, A.
    The Gram-positive Renibacterium salmoninarum causes bacterial kidney disease, a serious threat to Chilean salmon farming. To aid in vaccine development, this study used biochemical, antigenic, and genetic techniques to characterise 39 R. salmoninarum isolates from diseased Salmo salar and Oncorhynchus kisutch. Regardless of host, R. salmoninarum isolates were highly homogeneous pheno-typically. However, the isolates presented varied hydrophobicity (10-90%), as found by hydrocarbon adhesions, and distinct siderophores production, as evaluated on chrome azurol S agar. Serological assays established antigenic homogeneity among isolates, which can facilitate vaccine development. While western-blot profiles (using antiserum against iron-limited R. salmoninarum) differed, all isolates belonged to the same serogroup. Finally, RAPD, ERIC-PCR, and REP-PCR supported genetic R. salmoninarum homogeneity, suggesting clonal relationships. In conclusion, high homogeneity might facilitate vaccine development, but in vivo studies are needed to clarify the relationship of R. salmoninarum virulence with hydrophobicity/siderophores synthesis.
  • Miniatura
    Ítem
    Comparative genomic analysis of two Chilean Renibacterium salmoninarum isolates and the type strain ATCC 33209T
    (Oxford University Press, 2018-07) Bethke, J.; Yáñez, A.J.; Avendaño-Herrera, R.
    Renibacterium salmoninarum, a slow-growing facultative intracellular pathogen belonging to the high C+G content Actinobacteria phylum, is the causative agent of bacterial kidney disease, a progressive granulomatous infection affecting salmonids worldwide. This Gram-positive bacterium has existed in the Chilean salmonid industry for >30 years, but little or no information is available regarding the virulence mechanisms and genomic characteristics of Chilean isolates. In this study, the genomes of two Chilean isolates (H-2 and DJ2R)were sequenced, and a search was conducted for genes and proteins involved in virulence and pathogenicity, andwecompare with the type strain ATCC 33209T genome. The genome sizes of H-2 and DJ2R are 3,155,332 bp and 3,155,228 bp, respectively. They genomes presented six ribosomal RNA, 46 transcription RNA, and 25 noncodingRNA, and both had the same 56.27% G+C content described for the type strain ATCC 33209 T. A total of 3,522 and 3,527 coding sequences were found for H-2 and DJ2R, respectively. Meanwhile, the ATCC 33209T type strain had 3,519 coding sequences. The in silico genome analysis revealed a genes related to tricarboxylic acid cycle, glycolysis, iron transport and others metabolic pathway. Also, the data indicated that R salmoninarum may have a variety of possible virulence-factor and antibiotic-resistance strategies. Interestingly, many of genes had high identities with Mycobacterium species, a known pathogenic Actin obacteria bacterium. In summary, this study provides the first insights into and initial steps towards understanding the molecular basis of antibiotic resistance, virulence mechanisms and host/environment adaptation in twoChilean R. salmoninarum isolates that contain proteins of which were similar to those of Mycobacterium. Furthermore, important information is presented that could facilitate the development of preventive and treatment measures against R. salmoninarum in Chile and worldwide. © The Author(s) 2018.