Dispersal and Survival of Flavobacterium psychrophilum Phages<i>In Vivo</i>in Rainbow Trout and<i>In Vitro</i>under Laboratory Conditions: Implications for Their Use in Phage Therapy

Madsen, Lone; Bertelsen, Sif K.; Dalsgaard, Inger; Middelboe, Mathias

doi:10.1128/aem.00509-13

Cited by 42 publications

(45 citation statements)

References 19 publications

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“…Bacteriophages could decrease the opportunities of bacterial infections and may be an ecological approach to solve the problem. Some research showed that bacteriophages possess the ability to control the pathogens and reduce fish mortality rates in low-temperature aquaculture (Castillo et al 2014;Madsen et al 2013;Castillo et al 2012). For example, Flavobacterium psychrophilum is a fish pathogen that causes cold water disease, and it was verified that the lytic bacteriophage infecting F. psychrophilum could control this pathogen in artificial laboratory conditions (Castillo et al 2012).…”

Section: Discussionmentioning

confidence: 98%

Isolation and characterization of a novel lytic cold-active bacteriophage VNPH-1 from the Napahai wetland in China

Zhang

et al. 2014

Ann Microbiol

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Wetlands have unique characteristics and play a number of roles in the environment, principally in water purification, flood control, and the maintenance of shoreline stability. In this work, a lytic cold-active bacteriophage designated VNPH-1 was isolated from the Napahai wetland in China together with Aeromonas sobria NPH-1 cells, and a preliminary characterization of this bacteriophage was carried out. Electron microscopy revealed that VNPH-1 had an icosahedral head (116.7 nm) and a contractile tail (10 nm in width, 166.7 nm in length). Bacteriophage VNPH-1 was classified as Myoviridae and had an approximate genome size of 110 to 120 kb. One-step growth curve revealed that the latent and burst periods were 20 and 10 min, respectively, with an average burst size of 80 bacteriophage particles per infected cell. The pH and thermal stability of bacteriophage VNPH-1 were also investigated. The maximum stability of the bacteriophage was observed at an optimal pH of 9.0, and the phage was comparatively stable at pH 5.0-10.0. The specificity of this bacteriophage for its host makes it an attractive candidate for phage therapy of A. sobria infections. As VNPH-1 is a cold-active bacteriophage with a low production temperature, it would be worthwhile to characterize it further and to deepen knowledge of its interaction with A. sobria in future studies.

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Section: Discussionmentioning

confidence: 98%

Isolation and characterization of a novel lytic cold-active bacteriophage VNPH-1 from the Napahai wetland in China

Zhang

et al. 2014

Ann Microbiol

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“…Phages, which possess a different mode of action compared antibiotics, are expected to be an alternative to antibiotics (O'Flaherty et al, 2009). Controlling pathogens through the use of phages has been investigated for various applications such as therapeutic drugs for human, domestic animal, plants, hatchery fish, and food additives (Carvalho et al, 2010b;Gupta & Prasad, 2011;Addy et al, 2012;Chibeu et al, 2013;Madsen et al, 2013). However, studies on the growth inhibition of M. morganii by lytic phages have not been reported.…”

Section: Discussionmentioning

confidence: 99%

Characterization of a novelMorganella morganiibacteriophage FSP1 isolated from river water

Yamaki

Omachi

Kawai

et al. 2014

FEMS Microbiol Lett

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Morganella morganii has been identified as a causative agent of opportunistic infections and histamine poisoning. Bacteriophage is a virus and has recently been considered an alternative agent to antibiotics for the control of bacteria that have developed antibiotic resistance. In this study, a novel M. morganii bacteriophage isolated from river water was characterized. The isolated phage, termed FSP1, was purified by polyethylene glycol precipitation followed by cesium chloride density-gradient centrifugation. FSP1 has infectivity against only M. morganii and was identified as a Myoviridae bacteriophage through morphological analysis with transmission electron microscopy. According to the one-step growth curve, the FSP1 latent period, eclipse period, and burst size were 30, 20 min, and 42 PFU infected cell(-1) , respectively. The genome size of FSP1 was estimated to be c. 45.6-49.4 kb by restriction endonuclease analyses. Moreover, challenge testing against M. morganii in vitro revealed that FSP1 had high lytic activity and that the viable cell count of M. morganii was reduced by 6.12 log CFU mL(-1) after inoculation with FSP1 at a multiplicity of infection (MOI) = 10. These results suggested that FSP1 could be used as a biocontrol agent against M. morganii for treatment of infectious disease treatment or food decontamination.

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“…Several studies have presented detailed characterization of bacteriophages with lytic capacity against F. psychrophilum, emphasizing the potential of phages to control the pathogen and reduce its impact on fish mortality (6)(7)(8). However, as seen for treatment with antibiotics, phage control of bacteria is also challenged by the development of bacterial resistance against bacteriophages.…”

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confidence: 99%

Bacteriophage Resistance Mechanisms in the Fish Pathogen Flavobacterium psychrophilum: Linking Genomic Mutations to Changes in Bacterial Virulence Factors

Castillo

Christiansen

Dalsgaard

et al. 2015

Appl Environ Microbiol

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bFlavobacterium psychrophilum is an important fish pathogen in salmonid aquaculture worldwide. Due to increased antibiotic resistance, pathogen control using bacteriophages has been explored as a possible alternative treatment. However, the effective use of bacteriophages in pathogen control requires overcoming the selection for phage resistance in the bacterial populations. Here, we analyzed resistance mechanisms in F. psychrophilum after phage exposure using whole-genome sequencing of the ancestral phage-sensitive strain 950106-1/1 and six phage-resistant isolates. The phage-resistant strains had all obtained unique insertions and/or deletions and point mutations distributed among intergenic and genic regions. Mutations in genes related to cell surface properties, gliding motility, and biosynthesis of lipopolysaccharides and cell wall were found. The observed links between phage resistance and the genetic modifications were supported by direct measurements of bacteriophage adsorption rates, biofilm formation, and secretion of extracellular enzymes, which were all impaired in the resistant strains, probably due to superficial structural changes. The clustered regularly interspaced short palindromic repeat (CRISPR) region was unaffected in the resistant isolates and thus did not play a role as a resistance mechanism for F. psychrophilum under the current conditions. All together, the results suggest that resistance in F. psychrophilum was driven by spontaneous mutations, which were associated with a number of derived effects on the physiological properties of the pathogen, including reduced virulence under in vitro conditions. Consequently, phage-driven physiological changes associated with resistance may have implications for the impact of the pathogen in aquaculture, and these effects of phage resistance on host properties are therefore important for the ongoing exploration of phage-based control of F. psychrophilum. Flavobacterium psychrophilum is a well-known fish-pathogenic bacterium which causes the diseases rainbow trout fry syndrome (RTFS) and cold water disease (CWD). The pathogen occurs frequently in salmonid production sites and has been a problem in aquaculture worldwide since the first isolation in Washington, USA (1). Genetic characterization of F. psychrophilum strains has shown a low level of diversity with a distinct association of specific strains with particular fish species (2, 3). The complete genome sequence of the virulent F. psychrophilum strain JIPO2/86 (ATCC 49511) revealed a 2,861,988-bp circular chromosome with 2,432 predicted protein-coding genes. Among these predicted proteins, stress response mediators, gliding motility proteins, adhesins, and putative secreted proteases are probably involved in the pathogenesis of the bacterium (4).Due to increased resistance in F. psychrophilum to applied antibiotics (5), the use of lytic bacteriophages has been proposed as an alternative method for treatment of RTFS and CWD (6). Several studies have presented detailed characterization of bacteri...

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Dispersal and Survival of Flavobacterium psychrophilum PhagesIn Vivoin Rainbow Trout andIn Vitrounder Laboratory Conditions: Implications for Their Use in Phage Therapy

Cited by 42 publications

References 19 publications

Isolation and characterization of a novel lytic cold-active bacteriophage VNPH-1 from the Napahai wetland in China

Isolation and characterization of a novel lytic cold-active bacteriophage VNPH-1 from the Napahai wetland in China

Characterization of a novelMorganella morganiibacteriophage FSP1 isolated from river water

Bacteriophage Resistance Mechanisms in the Fish Pathogen Flavobacterium psychrophilum: Linking Genomic Mutations to Changes in Bacterial Virulence Factors

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