<i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains
Background: Although <i>Flavobacterium psychrophilum</i> is recognized as the causative pathogen of rainbow trout fry syndrome (RTFS), often resulting in high fry mortality, it is also responsible for bacterial cold water disease (BCWD) in large and older rainbow trout (<i>Oncorhyn...
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MDPI AG
2022-11-01
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| Series: | Biology |
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| Online Access: | https://www.mdpi.com/2079-7737/11/12/1701 |
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| author | Moonika H. Marana Inger Dalsgaard Per Walter Kania Abdu Mohamed Jens Hannibal Kurt Buchmann |
| author_facet | Moonika H. Marana Inger Dalsgaard Per Walter Kania Abdu Mohamed Jens Hannibal Kurt Buchmann |
| author_sort | Moonika H. Marana |
| collection | DOAJ |
| description | Background: Although <i>Flavobacterium psychrophilum</i> is recognized as the causative pathogen of rainbow trout fry syndrome (RTFS), often resulting in high fry mortality, it is also responsible for bacterial cold water disease (BCWD) in large and older rainbow trout (<i>Oncorhynchus mykiss</i>). These older fish do not experience high mortality, but sustain, through the shedding of bacteria, a constant infection pressure at farm level, which exposes fry to an unnecessary infection risk. We have produced and assessed the immunogenicity of an experimental injection BCWD vaccine, which may be used to decrease the shedding of bacteria from older fish. Methods: A total of 800 fish were i.p.-injected: 200 fish received the bacterin with adjuvant, 200 fish received the bacterin alone, 200 fish received adjuvant alone and 200 fish were injected with physiological saline. Blood samples were taken at day 0 and at three different time points (4, 8 and 14 weeks) post-vaccination. Plasma antibody levels were measured by ELISA for reactivity against both the homologous <i>F. psychrophilum</i> vaccine strain (serotype Fd) and heterologous strains (serotype Th). Results: Significantly elevated antibody titers were found against all serotypes in vaccinated fish. Welfare parameters associated with the vaccination process were evaluated by analyzing trout plasma samples for six different biochemical parameters, but no adverse effects associated with injection were indicated. Conclusions: The study suggests that an injection vaccine containing formalin-inactivated whole cells of <i>F. psychrophilum</i> (serotype Fd), adjuvanted with FIA, may also induce protection against heterologous strains. We advocate for, as the next step, the performance of field trials evaluating if the vaccination of older rainbow trout will (1) reduce the infection pressure in farms, (2) elevate the general health level in all groups and (3) minimize <i>F. psychrophilum</i> infection in fry at farm level. This may reduce the need for the administration of antibiotics in all age classes. |
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| last_indexed | 2024-03-09T17:19:26Z |
| publishDate | 2022-11-01 |
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| spelling | doaj.art-b3dc90d7891545e58fb3934eb70bf73e2023-11-24T13:21:53ZengMDPI AGBiology2079-77372022-11-011112170110.3390/biology11121701<i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different StrainsMoonika H. Marana0Inger Dalsgaard1Per Walter Kania2Abdu Mohamed3Jens Hannibal4Kurt Buchmann5Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, DenmarkUnit for Fish and Shellfish Diseases, National Institute of Aquatic Resources, Technical University of Denmark, DK-2800 Lyngby, DenmarkDepartment of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, DenmarkDepartment of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, DenmarkDepartment of Clinical Chemistry, Bispebjerg Hospital, DK-2400 Copenhagen, DenmarkDepartment of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, DenmarkBackground: Although <i>Flavobacterium psychrophilum</i> is recognized as the causative pathogen of rainbow trout fry syndrome (RTFS), often resulting in high fry mortality, it is also responsible for bacterial cold water disease (BCWD) in large and older rainbow trout (<i>Oncorhynchus mykiss</i>). These older fish do not experience high mortality, but sustain, through the shedding of bacteria, a constant infection pressure at farm level, which exposes fry to an unnecessary infection risk. We have produced and assessed the immunogenicity of an experimental injection BCWD vaccine, which may be used to decrease the shedding of bacteria from older fish. Methods: A total of 800 fish were i.p.-injected: 200 fish received the bacterin with adjuvant, 200 fish received the bacterin alone, 200 fish received adjuvant alone and 200 fish were injected with physiological saline. Blood samples were taken at day 0 and at three different time points (4, 8 and 14 weeks) post-vaccination. Plasma antibody levels were measured by ELISA for reactivity against both the homologous <i>F. psychrophilum</i> vaccine strain (serotype Fd) and heterologous strains (serotype Th). Results: Significantly elevated antibody titers were found against all serotypes in vaccinated fish. Welfare parameters associated with the vaccination process were evaluated by analyzing trout plasma samples for six different biochemical parameters, but no adverse effects associated with injection were indicated. Conclusions: The study suggests that an injection vaccine containing formalin-inactivated whole cells of <i>F. psychrophilum</i> (serotype Fd), adjuvanted with FIA, may also induce protection against heterologous strains. We advocate for, as the next step, the performance of field trials evaluating if the vaccination of older rainbow trout will (1) reduce the infection pressure in farms, (2) elevate the general health level in all groups and (3) minimize <i>F. psychrophilum</i> infection in fry at farm level. This may reduce the need for the administration of antibiotics in all age classes.https://www.mdpi.com/2079-7737/11/12/1701<i>Flavobacterium psychrophilum</i>rainbow trout fry syndromebacterial cold water diseaseaquacultureinjection vaccination |
| spellingShingle | Moonika H. Marana Inger Dalsgaard Per Walter Kania Abdu Mohamed Jens Hannibal Kurt Buchmann <i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains Biology <i>Flavobacterium psychrophilum</i> rainbow trout fry syndrome bacterial cold water disease aquaculture injection vaccination |
| title | <i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains |
| title_full | <i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains |
| title_fullStr | <i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains |
| title_full_unstemmed | <i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains |
| title_short | <i>Flavobacterium psychrophilum</i>: Response of Vaccinated Large Rainbow Trout to Different Strains |
| title_sort | i flavobacterium psychrophilum i response of vaccinated large rainbow trout to different strains |
| topic | <i>Flavobacterium psychrophilum</i> rainbow trout fry syndrome bacterial cold water disease aquaculture injection vaccination |
| url | https://www.mdpi.com/2079-7737/11/12/1701 |
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