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Levipan HA, Irgang R, Opazo LF, Araya-León H, Avendaño-Herrera R. Collective behavior and virulence arsenal of the fish pathogen Piscirickettsia salmonis in the biofilm realm. Front Cell Infect Microbiol 2022; 12:1067514. [PMID: 36544910 PMCID: PMC9760808 DOI: 10.3389/fcimb.2022.1067514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/14/2022] [Indexed: 12/12/2022] Open
Abstract
Piscirickettsiosis is a fish disease caused by the Gram-negative bacterium Piscirickettsia salmonis. This disease has a high socio-economic impact on the Chilean salmonid aquaculture industry. The bacterium has a cryptic character in the environment and their main reservoirs are yet unknown. Bacterial biofilms represent a ubiquitous mechanism of cell persistence in diverse natural environments and a risk factor for the pathogenesis of several infectious diseases, but their microbiological significance for waterborne veterinary diseases, including piscirickettsiosis, have seldom been evaluated. This study analyzed the in vitro biofilm behavior of P. salmonis LF-89T (genogroup LF-89) and CA5 (genogroup EM-90) using a multi-method approach and elucidated the potential arsenal of virulence of the P. salmonis LF-89T type strain in its biofilm state. P. salmonis exhibited a quick kinetics of biofilm formation that followed a multi-step and highly strain-dependent process. There were no major differences in enzymatic profiles or significant differences in cytotoxicity (as tested on the Chinook salmon embryo cell line) between biofilm-derived bacteria and planktonic equivalents. The potential arsenal of virulence of P. salmonis LF-89T in biofilms, as determined by whole-transcriptome sequencing and differential gene expression analysis, consisted of genes involved in cell adhesion, polysaccharide biosynthesis, transcriptional regulation, and gene mobility, among others. Importantly, the global gene expression profiles of P. salmonis LF-89T were not enriched with virulence-related genes upregulated in biofilm development stages at 24 and 48 h. An enrichment in virulence-related genes exclusively expressed in biofilms was also undetected. These results indicate that early and mature biofilm development stages of P. salmonis LF-89T were transcriptionally no more virulent than their planktonic counterparts, which was supported by cytotoxic trials, which, in turn, revealed that both modes of growth induced important and very similar levels of cytotoxicity on the salmon cell line. Our results suggest that the aforementioned biofilm development stages do not represent hot spots of virulence compared with planktonic counterparts. This study provides the first transcriptomic catalogue to select specific genes that could be useful to prevent or control the (in vitro and/or in vivo) adherence and/or biofilm formation by P. salmonis and gain further insights into piscirickettsiosis pathogenesis.
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Affiliation(s)
- Héctor A. Levipan
- Laboratorio de Ecopatología y Nanobiomateriales, Departamento de Ciencias y Geografía, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Valparaíso, Chile,Centro de Espectroscopía Atómica y Molecular (ATMOS-C), Universidad de Playa Ancha, Valparaíso, Chile,*Correspondence: Héctor A. Levipan, ; ; Ruben Avendaño-Herrera, ;
| | - Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile,Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - L. Felipe Opazo
- Institute of Ecology and Biodiversity (IEB), Santiago, Chile,Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Henry Araya-León
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile,Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile,Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile,Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile,*Correspondence: Héctor A. Levipan, ; ; Ruben Avendaño-Herrera, ;
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Delphino MKVC, Mardones FO, Neumann Heise J, Gallardo A, Jimenez D, Peña A, Rozas-Serri M, Gardner IA. Cost-effectiveness of longitudinal surveillance for Piscirickettsia salmonis using qPCR in Atlantic salmon farms (Salmo salar) in Chile. JOURNAL OF FISH DISEASES 2021; 44:315-326. [PMID: 33180978 DOI: 10.1111/jfd.13285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
Costs of diagnostic testing including sample collection, sampling frequency and sample size are an important consideration in the evaluation of the economic feasibility of alternative surveillance strategies for detection of infectious diseases in aquatic animals. In Chile, Piscirickettsia salmonis is the primary reason for antibiotic treatments in farmed Atlantic salmon. In 2012, a surveillance and control programme for piscirickettsiosis was established with an overall goal of reducing antibiotic use. The present study estimated the cost-effectiveness of different sampling frequencies and sample sizes to achieve at least 95% confidence of early detection of P. salmonis at the netpen and farm levels using a validated qPCR test. We developed a stochastic model that incorporated variability in test accuracy, within-pen prevalence and sampling costs. Our findings indicated that the current piscirickettsiosis surveillance programme based on risk-based sampling of five moribund or dead fish from 2 to 3 netpens is cost-effective and gives a high probability of detection of P. salmonis in Atlantic salmon farms in Chile at both the netpen and farm levels. Results from this study should incentivize salmon farmers to establish cost-effective strategies for early detection of P. salmonis infection and the application of this approach to other highly infectious diseases.
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Affiliation(s)
- Marina K V C Delphino
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada
| | - Fernando O Mardones
- School of Veterinary Medicine, Pontifical Catholic University of Chile, Santiago, Chile
| | - Joaquin Neumann Heise
- School of Veterinary Medicine, Pontifical Catholic University of Chile, Santiago, Chile
| | | | | | - Andrea Peña
- Pathovet Laboratory Ltd, Puerto Montt, Chile
| | | | - Ian A Gardner
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada
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