TY - BOOK

T1 - Bacteriophage interactions with Vibrio anguillarum and the potential for phage therapy in marine aquaculture

AU - Rørbo, Nanna Iben

PY - 2017

Y1 - 2017

N2 - The aquaculture industry is expanding due to an increasing demand for food with the world’spopulation growing. However, aquaculture often experience disease outbreaks generally causedby opportunistic pathogens, including Vibrio anguillarum. This bacterium is the causative agentof the disease vibriosis which affects a lot of different fish species. As in the rest of the world, anincrease in antibiotic resistant bacteria is also observed in the aquaculture industry makingchemotherapeutics futile. Bacteriophage therapy offers a great potential in treatment and controlof Vibrio anguillarum in aquaculture, however, more knowledge is needed regarding the phagehostinteraction in order to accomplish success. The current PhD thesis address the phage-hostinteractions in Vibrio anguillarum and the potential of phage therapy in treating vibriosis outbreaksin eggs and larvae of cod and turbot.Lysogeny is widespread in the Vibrio community which underscore the lysogenic phages influenceon bacterial evolution and functional properties. Highly genetically similar Vibrio phages, termedH20-like prophages, were isolated across large geographical scales being present both as freelivingphages and as prophages in V. anguillarum genomes. The H20-like phages’ widespreadpresence suggests a mutualistic interaction which selects for co-existence with V. anguillarum.In aquaculture, especially the larvae and fry are vulnerable to pathogens, and they are notsusceptible to alternatives to antibiotics, e.g. vaccines. The lytic broad-host-range phage KVP40was applied to cod and turbot larvae to control different V. anguillarum strains. We observed thatphage KVP40 was able to reduce and/or delay the mortality. Further, phage KVP40 was also ableto reduced the mortality imposed by the natural bacterial background present in the larvae,emphasizing its potential as a therapeutic agent.In phage therapy the resistance mechanisms after phage exposure and the impact on the host arenot fully understood. A molecular and mechanistic understanding of resistance mechanisms andvirulence properties of the host is essential for developing properly phage therapy. In this PhDthesis phage-resistant V. anguillarum strains were whole-genome sequenced to explain differentresistance mechanisms, and their virulence properties were tested on cod larvae. The strainsconsisted of both non-mutational and mutational resistance mechanisms, probably depending onphage exposure and environmental conditions, which affected the pathogenicity.

AB - The aquaculture industry is expanding due to an increasing demand for food with the world’spopulation growing. However, aquaculture often experience disease outbreaks generally causedby opportunistic pathogens, including Vibrio anguillarum. This bacterium is the causative agentof the disease vibriosis which affects a lot of different fish species. As in the rest of the world, anincrease in antibiotic resistant bacteria is also observed in the aquaculture industry makingchemotherapeutics futile. Bacteriophage therapy offers a great potential in treatment and controlof Vibrio anguillarum in aquaculture, however, more knowledge is needed regarding the phagehostinteraction in order to accomplish success. The current PhD thesis address the phage-hostinteractions in Vibrio anguillarum and the potential of phage therapy in treating vibriosis outbreaksin eggs and larvae of cod and turbot.Lysogeny is widespread in the Vibrio community which underscore the lysogenic phages influenceon bacterial evolution and functional properties. Highly genetically similar Vibrio phages, termedH20-like prophages, were isolated across large geographical scales being present both as freelivingphages and as prophages in V. anguillarum genomes. The H20-like phages’ widespreadpresence suggests a mutualistic interaction which selects for co-existence with V. anguillarum.In aquaculture, especially the larvae and fry are vulnerable to pathogens, and they are notsusceptible to alternatives to antibiotics, e.g. vaccines. The lytic broad-host-range phage KVP40was applied to cod and turbot larvae to control different V. anguillarum strains. We observed thatphage KVP40 was able to reduce and/or delay the mortality. Further, phage KVP40 was also ableto reduced the mortality imposed by the natural bacterial background present in the larvae,emphasizing its potential as a therapeutic agent.In phage therapy the resistance mechanisms after phage exposure and the impact on the host arenot fully understood. A molecular and mechanistic understanding of resistance mechanisms andvirulence properties of the host is essential for developing properly phage therapy. In this PhDthesis phage-resistant V. anguillarum strains were whole-genome sequenced to explain differentresistance mechanisms, and their virulence properties were tested on cod larvae. The strainsconsisted of both non-mutational and mutational resistance mechanisms, probably depending onphage exposure and environmental conditions, which affected the pathogenicity.

UR - https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122741135505763

M3 - Ph.D. thesis

BT - Bacteriophage interactions with Vibrio anguillarum and the potential for phage therapy in marine aquaculture

PB - Department of Biology, Faculty of Science, University of Copenhagen

ER -