RESUMO
Renibacterium salmoninarum is the aetiological agent of bacterial kidney disease (BKD) in salmonid farms. This pathogen possesses at least three iron-acquisition mechanisms, but the link between these mechanisms and virulence is unclear. Therefore, this study used RT-qPCR to assess the effects of normal and iron-limited conditions on iron-uptake genes controlled by IdeR and related to iron acquisition in Chilean R. salmoninarum strain H-2 and the type strain DSM20767T . Further evaluated was the in vitro immune-related response of the Atlantic Salmon Kidney (ASK) cell line, derived from the primary organ affected by BKD. R. salmoninarum grown under iron-limited conditions overexpressed genes involved in haemin uptake and siderophore transport, with overexpression significantly higher in H-2 than DSM20767T . These overexpressed genes resulted in higher cytotoxicity and an increased immune response (i.e., TNF-α, IL-1ß, TLR1 and INF-γ) in the ASK cell line. This response was significantly higher against bacteria grown under iron-limited conditions, especially H-2. These observations indicate that iron-acquisition mechanisms are possibly highly related to the virulence and pathogenic capacity of R. salmoninarum. In conclusion, treatments that block iron-uptake mechanisms or siderophore synthesis are attractive therapeutic approaches for treating R. salmoninarum, which causes significant aquaculture losses.
Assuntos
Infecções por Actinomycetales/veterinária , Doenças dos Peixes/imunologia , Ferro/metabolismo , Micrococcaceae/imunologia , Micrococcaceae/patogenicidade , Salmo salar , Infecções por Actinomycetales/imunologia , Infecções por Actinomycetales/metabolismo , Infecções por Actinomycetales/microbiologia , Animais , Linhagem Celular , Doenças dos Peixes/metabolismo , Doenças dos Peixes/microbiologia , Imunidade Inata , Micrococcaceae/metabolismo , Renibacterium , VirulênciaRESUMO
Infectious diseases affecting wildlife are drivers of global biodiversity loss. Here we report a bacterial threat to endangered wild reptiles. Since April 2011, a severe skin disease has affected free-ranging, endangered Lesser Antillean iguanas (Iguana delicatissima) on the French Caribbean island of Saint Barthélemy and we identified Devriesea agamarum as the causative agent. The presence of this bacterium was also demonstrated in healthy lizards (anoles) co-inhabiting the island. All isolates from the iguanas corresponded to a single AFLP genotype that until now has exclusively been associated with infections in lizard species in captivity. The clonal relatedness of the isolates and recent emergence of the disease suggest recent arrival of a virulent D. agamarum clone on the island. The presence of healthy but infected lizards suggests the presence of asymptomatic reservoir hosts. This is the first description of a bacterial disease that poses a conservation threat towards free-ranging squamates.