Assessment of cross‐protection to heterologous strains of <i>Flavobacterium psychrophilum</i> following vaccination with a live‐attenuated coldwater disease immersion vaccine

Ma, Jie; Bruce, Timothy J.; Sudheesh, Ponnerassery S.; Knupp, Christopher; Loch, Thomas P.; Faisal, Mohamed; Cain, Kenneth D.

doi:10.1111/jfd.12902

Cited by 29 publications

(15 citation statements)

References 36 publications

(77 reference statements)

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“…Based on our previous challenge experiments and published researches, in the present study, the fish were infected with 10 times reducing dose of IHNV/F. psychrophilum challenge model as described before (LaFrentz et al, ; LaPatra, ; Ma et al, ). This dose induced fish were no asymptomatic carriers and low mortality.…”

Section: Discussionmentioning

confidence: 99%

Co‐infection of rainbow trout (Oncorhynchus mykiss) with infectious hematopoietic necrosis virus and Flavobacterium psychrophilum

Bruce

Oliver

et al. 2019

Journal of Fish Diseases

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Co-infection of rainbow trout with infections haematopoietic necrosis virus (IHNV)and Flavobacterium psychrophilum is known to occur, and it has been speculated that a combined infection can result in dramatic losses. Both pathogens can persist in fish in an asymptomatic carrier state, but the impact of co-infection has not been well characterized or documented. In this study, it was hypothesized that fish co-infected with F. psychrophilum and IHNV would exhibit greater mortality than fish infected with either pathogen alone. To test this, juvenile rainbow trout were co-infected with low doses of either IHNV or F. psychrophilum, and at 2 days post-initial challenge, they were given a low dose of the reciprocal pathogen. This combined infection caused high mortality (76.2%-100%), while mortality from a single pathogen infection with the same respective dose was low (5%-20%). The onset of mortality was earlier in the co-infected group (3-4 days) when compared with fish infected with F. psychrophilum alone (6 days) or IHNV (5 days), confirming the synergistic interaction between both pathogens. Co-infection led to a significant increase in the number of F. psychrophilum colony-forming units and IHNV plaque-forming units within tissues. This finding confirms that when present together in co-infected fish, both pathogens are more efficiently recovered from tissues. Furthermore, pathogen genes were significantly increased in co-infected groups, which parallel the findings of increased systemic pathogen load. Extensive tissue necrosis and abundant pathogen present intracellularly and extracellularly in haematopoietic tissue. This was pronounced in co-infected fish and likely contributed to the exacerbated clinical signs and higher mortality. This study provides novel insight into host-pathogen interactions related to co-infection by aquatic bacterial and viral pathogens and supports our hypothesis. Such findings confirm that mortality in fish exposed to both pathogens is greatly elevated compared to a single pathogen infection. K E Y W O R D S co-infection, Flavobacterium psychrophilum, IHNV, rainbow trout How to cite this article: Ma J, Bruce TJ, Oliver L, Cain KD. Co-infection of rainbow trout (Oncorhynchus mykiss) with infectious haematopoietic necrosis virus and Flavobacterium psychrophilum. J Fish Dis. 2019;42:1065-1076. https ://doi.

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Section: Discussionmentioning

confidence: 99%

Co‐infection of rainbow trout (Oncorhynchus mykiss) with infectious hematopoietic necrosis virus and Flavobacterium psychrophilum

Bruce

Oliver

et al. 2019

Journal of Fish Diseases

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“…A previously developed and reported live-attenuated immersion vaccine (F. psychrophilum; B.17-ILM) has been shown to confer significant protection in salmonids. To further characterize this vaccine, experiments were carried out to determine the cross-protective efficacy of this B.17-ILM vaccine against nine F. psychrophilum isolates (representing seven sequence types/three clonal complexes, as determined by multi-locus sequence typing) in comparison with a wild-type virulent strain, CSF-259-93 [96]. To assess protection, experimental challenges of rainbow trout fry were conducted following immersion vaccinations with the B.17-ILM vaccine.…”

Section: Rainbow Trout Fry Syndrome/bacterial Cold-water Disease (Rtfmentioning

confidence: 99%

Review on Immersion Vaccines for Fish: An Update 2019

Bøgwald

Dalmo

2019

Microorganisms

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Immersion vaccines are used for a variety of aquacultured fish to protect against infectious diseases caused by bacteria and viruses. During immersion vaccination the antigens are taken up by the skin, gills or gut and processed by the immune system, where the resulting response may lead to protection. The lack of classical secondary responses following repeated immersion vaccination may partly be explained by the limited uptake of antigens by immersion compared to injection. Administration of vaccines depends on the size of the fish. In most cases, immersion vaccination is inferior to injection vaccination with regard to achieved protection. However, injection is problematic in small fish, and fry as small as 0.5 gram may be immersion vaccinated when they are considered adaptively immunocompetent. Inactivated vaccines are, in many cases, weakly immunogenic, resulting in low protection after immersion vaccination. Therefore, during recent years, several studies have focused on different ways to augment the efficacy of these vaccines. Examples are booster vaccination, administration of immunostimulants/adjuvants, pretreatment with low frequency ultrasound, use of live attenuated and DNA vaccines, preincubation in hyperosmotic solutions, percutaneous application of a multiple puncture instrument and application of more suitable inactivation chemicals. Electrostatic coating with positively charged chitosan to obtain mucoadhesive vaccines and a more efficient delivery of inactivated vaccines has also been successful.

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“…Ma et al. (2019) previously reported that US149 was virulent in juvenile rainbow trout, producing a CPM of 52% with a dose of 8.50 x 10 7 CFU fish ‐1 . The US149 was originally isolated from Atlantic salmon in Washington, USA, while the US063 was isolated from another salmonid species, lake trout, in Michigan, USA.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Flavobacterium psychrophilum‐associated mortality in Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis)

Bruce

Jones

et al. 2021

Journal of Fish Diseases

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Salmonid diseases caused by infections of Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease, remain difficult to manage as novel, pathogenic strains continue to emerge in aquaculture settings globally. To date, much of the research regarding treatment options and vaccine development has focused on rainbow trout (Oncorhynchus mykiss), but other inland‐reared salmonids are also impacted by this Gram‐negative bacterium. As such, Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) were injection‐challenged with a variety of previously reported F. psychrophilum strains isolated from disease diagnostic cases in salmonids, as well as a standard and well‐studied F. psychrophilum strain (CSF 259–93) known to be virulent in rainbow trout. In three separate virulence assessments (Trials A, B and C), strains US063 (isolated from lake trout; Salvelinus namaycush) and US149 (isolated from Atlantic salmon) caused a significantly higher cumulative per cent mortality (CPM) relative to other strains in Atlantic salmon (p <.001 for all trials), with US149 causing significantly greater mortality than US063 in Trials A (CPM 97% vs. 65%, p =.008) and B (CPM 96% ± 2.3% vs. 81.33% ± 4.8%, p =.014). Trial C used a lower dose (1.86 × 108 CFU/mL) for US149, resulting in a lower mortality (78.67% ± 9.33%) relative to Trials A and B. CSF259‐93 did not cause significant mortality in any trials. In brook trout, the strain 03–179 (originally isolated from steelhead trout; Oncorhynchus mykiss) was significantly more virulent than any other (CPM 100% ± 0%, p <.001), followed by US063 (73% ± 3.8%) and US149 (40% ± 6.1%,) respectively. Again, CSF259‐93 did not cause significant mortality relative to a mock challenge treatment. Results provide information about the applicability of strain selection in F. psychrophilum virulence testing in Atlantic salmon and brook trout, demonstrating the high virulence of US063 and US149 for these salmonid species. This information is applicable for the development of therapeutics and vaccines against F. psychrophilum infections and demonstrates the reproducibility of the experimental challenge model.

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Assessment of cross‐protection to heterologous strains of Flavobacterium psychrophilum following vaccination with a live‐attenuated coldwater disease immersion vaccine

Cited by 29 publications

References 36 publications

Co‐infection of rainbow trout (Oncorhynchus mykiss) with infectious hematopoietic necrosis virus and Flavobacterium psychrophilum

Co‐infection of rainbow trout (Oncorhynchus mykiss) with infectious hematopoietic necrosis virus and Flavobacterium psychrophilum

Review on Immersion Vaccines for Fish: An Update 2019

Assessment of Flavobacterium psychrophilum‐associated mortality in Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis)

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