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At least 73 records · Page 4Linked to original sources

USGS2004

Quantitative expression profiling of immune response genes in rainbow trout following infectious haematopoietic necrosis virus (IHNV) infection or DNA vaccination

Infectious haematopoietic necrosis virus (IHNV) is a well-studied virus of salmonid fishes. A highly efficacious DNA vaccine has been developed against this virus and studies have demonstrated that this vaccine induces both an early and transient non-specific anti-viral phase as well as long-term specific protection. The mechanisms of the early anti-viral phase are not known, but previous studies noted changes in Mx gene expression, suggesting a role for type I interferon. This study used quantitative real-time reverse transcriptase PCR methodology to compare expression changes over time of a number of cytokine or cytokine-related genes in the spleen of rainbow trout following injection with poly I:C, live IHNV, the IHNV DNA vaccine or a control plasmid encoding the non-antigenic luciferase gene. The target genes included Mx-1, viral haemorrhagic septicaemia virus induced gene 8 (Vig-8), TNF-α1, TNF-α2, IL-1β1, IL-8, TGF-β1 and Hsp70. Poly I:C stimulation induced several genes but the strongest and significant response was observed in the Mx-1 and Vig-8 genes. The live IHN virus induced a significant response in all genes examined except TGF-β1. The control plasmid construct and the IHNV DNA vaccine marginally induced a number of genes, but the main difference between these two groups was a statistically significant induction of the Mx-1 and Vig-8 genes by the IHNV vaccine only. The gene expression profiles elicited by the live virus and the IHNV DNA vaccine differed in a number of aspects but this study confirms the clear role for a type I interferon-like response in early anti-viral defence.

Fish & Shellfish Immunology↗

USGS2006

Comprehensive gene expression profiling following DNA vaccination of rainbow trout against infectious hematopoietic necrosis virus

The DNA vaccine based on the glycoprotein gene of Infectious hematopoietic necrosis virus induces a non-specific anti-viral immune response and long-term specific immunity against IHNV. This study characterized gene expression responses associated with the early anti-viral response. Homozygous rainbow trout were injected intra-muscularly (I.M.) with vector DNA or the IHNV DNA vaccine. Gene expression in muscle tissue (I.M. site) was evaluated using a 16,008 feature salmon cDNA microarray. Eighty different genes were significantly modulated in the vector DNA group while 910 genes were modulated in the IHNV DNA vaccinate group relative to control group. Quantitative reverse-transcriptase PCR was used to examine expression of selected immune genes at the I.M. site and in other secondary tissues. In the localized response (I.M. site), the magnitudes of gene expression changes were much greater in the vaccinate group relative to the vector DNA group for the majority of genes analyzed. At secondary systemic sites (e.g. gill, kidney and spleen), type I IFN-related genes were up-regulated in only the IHNV DNA vaccinated group. The results presented here suggest that the IHNV DNA vaccine induces up-regulation of the type I IFN system across multiple tissues, which is the functional basis of early anti-viral immunity.

Molecular Immunology↗

USGS2017

Influence of temperature on the efficacy of homologous and heterologous DNA vaccines against viral hemorrhagic septicemia in Pacific Herring

Homologous and heterologous (genogroup Ia) DNA vaccines against viral hemorrhagic septicemia virus (genogroup IVa) conferred partial protection in Pacific Herring Clupea pallasii . Early protection at 2 weeks postvaccination (PV) was low and occurred only at an elevated temperature (12.6°C, 189 degree days), where the relative percent survival following viral exposure was similar for the two vaccines (IVa and Ia) and higher than that of negative controls at the same temperature. Late protection at 10 weeks PV was induced by both vaccines but was higher with the homologous vaccine at both 9.0°C and 12.6°C. Virus neutralization titers were detected among 55% of all vaccinated fish at 10 weeks PV. The results suggest that the immune response profile triggered by DNA vaccination of herring was similar to that reported for Rainbow Trout Oncorhynchus mykiss by Lorenzen and LaPatra in 2005, who found interferon responses in the early days PV and the transition to adaptive response later. However, the protective effect was far less prominent in herring, possibly reflecting different physiologies or adaptations of the two fish species.

Journal of Aquatic Animal Health↗

USGS1998

Molecular approaches to fish vaccines

For more than 50 years, researchers have tested a variety of killed, attenuated, and subunit preparations for control offish diseases. The earliest fish vaccines used killed preparations containing whole bacteria, viruses, or parasites and today, several bacterins have become commercially successful with more expected as improved delivery systems and adjuvants are realized. Live, attenuated vaccines have been developed by serial passage of a pathogen in culture or by using naturally occurring mutants and cross-reacting strains. These generally offer excellent protection and are cost-effective, but concerns about residual virulence or their effects on other aquatic species make them difficult candidates for licensing. In recent years, the tools of molecular biology have been applied to construction of a variety of recombinant, engineered, or subunit vaccines for fish. Among the approaches to be discussed are: attenuated strains of viruses and bacteria created by deletion of specific genes associated with virulence, in vitro synthesis of protective antigens from genes cloned into E. coli or baculovirus expression systems, chemical synthesis of peptides that represent protective epitopes, and direct immunization with DNA coding for protective antigens. Preparations representing each of these approaches have been tested in laboratory or field trials with various results and such vaccines promise to be safe and relatively inexpensive if they are able to provide protection when delivered by immersion. A significant advantage of genetically engineered vaccines is the ability to construct multivalent preparations that can protect fish against several pathogens or different strains of the same pathogen. While many of these novel vaccine strategies have been effective at stimulating specific immunity in the laboratory, more work is needed to develop better delivery systems and to overcome potential regulatory concerns.

Journal of Applied Ichthyology↗

USGS2024

Developing transmissible vaccines for animal infections

Many emerging and reemerging pathogens originate from wildlife, but nearly all wild species are unreachable using conventional vaccination, which requires capture of and vaccine administration to individual animals. By enabling immunization at scales sufficient to interrupt pathogen transmission, transmissible vaccines (TVs) that spread themselves through wildlife populations by infectious processes could potentially transform the management of otherwise intractable challenges to public health, wildlife conservation, and animal welfare. However, generating TVs likely requires modifying viruses that would be intended to spread in nature, which raises concerns ranging from technical feasibility, to safety and security risks, to regulatory uncertainties ( 1 , 2 ). We propose a series of commitments and strategies for vaccine development—beginning with a priori decisions on vaccine design and continuing through to stakeholder codevelopment [see supplementary materials (SM)]—that we believe increase the likelihood that the potential risks of vaccine transmission are outweighed by benefits to conservation, animal welfare, and zoonosis prevention.

Science↗

USGS1999

Biosafety of parenteral Brucella abortus RB51 vaccine in bison calves

Vaccination is considered among the primary management tools for reducing brucellosis prevalence in Greater Yellowstone Area (GYA) ungulates. Before their use, however, vaccine safety and efficacy must be demonstrated. Twenty-seven female bison (Bison bison) calves (approx 5 months old) were vaccinated with Brucella abortus Strain RB51 (1.5 × 1010 colony forming units [CFU], subcutaneously) as part of routine management. We assessed the persistence, pathology, shedding, and transmission associated with RB51 by serial necropsy, bacteriology, histopathology, and serology of 20 of these 27 vaccinated calves, and RB51 serology of 10 nonvaccinated, commingling adult females. With the exception of 1 calf, RB51 dot-blot titers at necropsy were <1:80. Strain RB51 was cultured from lymph nodes in 4 of 4 calves at 14 weeks postvaccination (PV), 4 of 4 calves at 18 weeks PV, 1 of 4 calves at 22 weeks PV, 3 of 4 at 26 weeks PV, and 0 of 4 calves at 30 weeks PV. No gross lesions were observed. Mild histologic changes occurred only in a few draining lymph nodes early in sampling. Adverse clinical effects were not observed in vaccinates. Swabs from nasopharynx, conjunctiva, rectum, and vagina were uniformly culture negative for RB51. Strain RB51 dot-blot assays of bison cows were negative at a 1:20 dilution at 26 weeks PV. Our results suggest that RB51 persists longer in bison calves than in domestic cattle and is systemically distributed within lymphatic tissues. However, bison apparently clear the RB51 vaccine strain without shedding, transmission, or significant adverse reactions.

Journal of Wildlife Management↗

USGS1999

Evaluation of the protective immunogencity of the N, P, M, NV and G proteins of infectious hematopoietic necrosis virus in rainbow trout Oncorhynchus mykiss using DNA vaccines

The protective immunogenicity of the nucleoprotein (N), phosphoprotein (P), matrix protein (M), non-virion protein (NV) and glycoprotein (G) of the rhabdovirus infectious hematopoietic necrosis virus (IHNV) was assessed in rainbow trout using DNA vaccine technology. DNA vaccines were produced by amplifying and cloning the viral genes in the plasmid pCDNA 3.1. The protective immunity elicited by each vaccine was evaluated through survival of immunized fry after challenge with live virus. Neutralizing antibody titers were also determined in vaccinated rainbow trout Oncorhynchus mykiss fry (mean weight 2 g) and 150 g sockeye salmon Oncorhynchus nerka . The serum from the 150 g fish was also used in passive immunization studies with naïve fry. Our results showed that neither the internal structural proteins (N, P and M) nor the NV protein of IHNV induced protective immunity in fry or neutralizing antibodies in fry and 150 g fish when expressed by a DNA vaccine construct. The G protein, however, did confer significant protection in fry up to 80 d post-immunization and induced protective neutralizing antibodies. We are currently investigating the role of different arms of the fish immune system that contribute to the high level of protection against IHNV seen in vaccinated fish.

Diseases of Aquatic Organisms↗

USGS2022

Projected resurgence of COVID-19 in the United States in July—December 2021 resulting from the increased transmissibility of the Delta variant and faltering vaccination

In Spring 2021, the highly transmissible SARS-CoV-2 Delta variant began to cause increases in cases, hospitalizations, and deaths in parts of the United States. At the time, with slowed vaccination uptake, this novel variant was expected to increase the risk of pandemic resurgence in the US in summer and fall 2021. As part of the COVID-19 Scenario Modeling Hub, an ensemble of nine mechanistic models produced 6-month scenario projections for July–December 2021 for the United States. These projections estimated substantial resurgences of COVID-19 across the US resulting from the more transmissible Delta variant, projected to occur across most of the US, coinciding with school and business reopening. The scenarios revealed that reaching higher vaccine coverage in July–December 2021 reduced the size and duration of the projected resurgence substantially, with the expected impacts was largely concentrated in a subset of states with lower vaccination coverage. Despite accurate projection of COVID-19 surges occurring and timing, the magnitude was substantially underestimated 2021 by the models compared with the of the reported cases, hospitalizations, and deaths occurring during July–December, highlighting the continued challenges to predict the evolving COVID-19 pandemic. Vaccination uptake remains critical to limiting transmission and disease, particularly in states with lower vaccination coverage. Higher vaccination goals at the onset of the surge of the new variant were estimated to avert over 1.5 million cases and 21,000 deaths, although may have had even greater impacts, considering the underestimated resurgence magnitude from the model.

eLife↗

USGS1987

Antibody response of sandhill and whooping cranes to an eastern equine encephalitis virus vaccine

As a possible strategy to protect whooping cranes (Grus americana) from fatal eastern equine encephalitis (EEE) viral infection, studies were conducted to determine the immune response of this species and sandhill cranes (Grus canadensis) to a formalin-inactivated EEE viral vaccine. Viral-specific neutralizing antibody was elicited in both species after intramuscular (IM) vaccination. Subcutaneous and intravenous routes of vaccination failed to elicit detectable antibody in sandhill cranes. Among the IM vaccinated cranes, the immune response was characterized by nondetectable or low antibody titers that waned rapidly following primary exposure to the vaccine. However, one or more booster doses consistently elicited detectable antibody and/or increased antibody titers in the whooping cranes. In contrast, cranes with pre-existing EEE viral antibody, apparently induced by natural infection, exhibited a rapid increase and sustained high-antibody titers. Even though EEE virus vaccine induced neutralizing antibody and produced no adverse side effects, further studies will be required to determine the protective efficacy of the antibody.

Journal of Wildlife Diseases↗

USGS2008

Vaccination with F1-V fusion protein protects black-footed ferrets (Mustela nigripes) against plague upon oral challenge with Yersinia pestis

Previous studies have established that vaccination of black-footed ferrets ( Mustela nigripes ) with F1-V fusion protein by subcutaneous (SC) injection protects the animals against plague upon injection of the bacterium Yersinia pestis . This study demonstrates that the F1-V antigen can also protect ferrets against plague contracted via ingestion of a Y. pestis -infected mouse, a probable route for natural infection. Eight black-footed ferret kits were vaccinated with F1-V protein by SC injection at approximately 60 days-of-age. A booster vaccination was administered 3 mo later via SC injection. Four additional ferret kits received placebos. The animals were challenged 6 wk after the boost by feeding each one a Y. pestis -infected mouse. All eight vaccinates survived challenge, while the four controls succumbed to plague within 3 days after exposure. To determine the duration of antibody postvaccination, 18 additional black-footed ferret kits were vaccinated and boosted with F1-V by SC injection at 60 and 120 days-of-age. High titers to both F1 and V (mean reciprocal titers of 18,552 and 99,862, respectively) were found in all vaccinates up to 2 yr postvaccination, whereas seven control animals remained antibody negative throughout the same time period.

Journal of Wildlife Diseases↗

USGS2001

Protection of rainbow trout against infectious hematopoietic necrosis virus four days after specific or semi-specific DNA vaccination

A DNA vaccine against a fish rhabdovirus, infectious hematopoietic necrosis virus (IHNV), was shown to provide significant protection as soon as 4 d after intramuscular vaccination in 2 g rainbow trout ( Oncorhynchus mykiss ) held at 15°C. Nearly complete protection was also observed at later time points (7, 14, and 28 d) using a standardized waterborne challenge model. In a test of the specificity of this early protection, immunization of rainbow trout with a DNA vaccine against another fish rhabdovirus, viral hemorrhagic septicemia virus, provided a significant level of cross-protection against IHNV challenge for a transient period of time, whereas a rabies virus DNA vaccine was not protective. This indication of distinct early and late protective mechanisms was not dependent on DNA vaccine doses from 0.1 to 2.5 μg.

Vaccine↗

USGS2017

Sylvatic plague vaccine partially protects prairie dogs (Cynomys spp.) in field trials

Sylvatic plague, caused by Yersinia pestis , frequently afflicts prairie dogs ( Cynomys spp.), causing population declines and local extirpations. We tested the effectiveness of bait-delivered sylvatic plague vaccine (SPV) in prairie dog colonies on 29 paired placebo and treatment plots (1–59 ha in size; average 16.9 ha) in 7 western states from 2013 to 2015. We compared relative abundance (using catch per unit effort (CPUE) as an index) and apparent survival of prairie dogs on 26 of the 29 paired plots, 12 with confirmed or suspected plague ( Y. pestis positive carcasses or fleas). Even though plague mortality occurred in prairie dogs on vaccine plots, SPV treatment had an overall positive effect on CPUE in all three years, regardless of plague status. Odds of capturing a unique animal were 1.10 (95% confidence interval [C.I.] 1.02–1.19) times higher per trap day on vaccine-treated plots than placebo plots in 2013, 1.47 (95% C.I. 1.41–1.52) times higher in 2014 and 1.19 (95% C.I. 1.13–1.25) times higher in 2015. On pairs where plague occurred, odds of apparent survival were 1.76 (95% Bayesian credible interval [B.C.I.] 1.28–2.43) times higher on vaccine plots than placebo plots for adults and 2.41 (95% B.C.I. 1.72–3.38) times higher for juveniles. Our results provide evidence that consumption of vaccine-laden baits can protect prairie dogs against plague; however, further evaluation and refinement are needed to optimize SPV use as a management tool.

EcoHealth↗

USGS2021

Effects of experimental flea removal and plague vaccine treatments on survival of northern Idaho ground squirrels and two coexisting sciurids

Plague is a non-native disease in North America that reduces survival of many mammals. Previous studies have focused on epizootic plague which causes acute mortality events and dramatic declines in local abundance. We know much less about enzootic plague which causes less punctuated reductions in survival and abundance of infected populations. As a result, enzootic plague is much more difficult to detect because changes in population attributes are more subtle and Yersinia pestis prevalence is likely lower relative to epizootic plague outbreaks. The northern Idaho ground squirrel ( Urocitellus brunneus ) is a threatened species which coexists with Columbian ground squirrels ( Urocitellus columbianus ) and yellow-pine chipmunks ( Neotamias amoenus ) throughout their restricted distribution in central Idaho. Columbian ground squirrels and yellow-pine chipmunks are more abundant and widespread than northern Idaho ground squirrels and both are known hosts for plague. Hence, enzootic plague may be one cause of rarity for northern Idaho ground squirrels but its effect on this threatened species has not been evaluated. We conducted three controlled and randomized field experiments to examine the effects of plague in northern Idaho ground squirrels and the two coexisting species: 1) a plague vaccine experiment, 2) a paired flea-reduction experiment, and 3) a non-paired flea-reduction experiment. For Experiment 1, we hypothesized that if enzootic plague is present, vaccinated animals would have higher survival. Furthermore, Experiments 2 and 3 tested the prediction that untreated, control animals should have lower survival than those in areas where fleas are experimentally removed or reduced because fleas are the main vector for plague. In the plague vaccine experiment, vaccinated chipmunks had 4.65% higher apparent survival compared to chipmunks that received a placebo for intervals when the vaccine is believed to be effective. Apparent annual survival increased for all three species on experimental flea-reduction plots compared to non-treated plots for the paired experiment but results were mixed for the non-paired experiment. Taken together, our results suggest that enzootic plague is present and negatively impacting survival of northern Idaho ground squirrels and two coexisting species.

Idaho↗

USGS2019

Virally-vectored vaccine candidates against white-nose syndrome induce anti-fungal immune response in little brown bats (Myotis lucifugus)

White-nose syndrome (WNS) caused by the fungus, Pseudogymnoascus destructans ( Pd ) has killed millions of North American hibernating bats. Currently, methods to prevent the disease are limited. We conducted two trials to assess potential WNS vaccine candidates in wild-caught Myotis lucifugus . In a pilot study, we immunized bats with one of four vaccine treatments or phosphate-buffered saline (PBS) as a control and challenged them with Pd upon transfer into hibernation chambers. Bats in one vaccine-treated group, that received raccoon poxviruses (RCN) expressing Pd calnexin (CAL) and serine protease (SP), developed WNS at a lower rate (1/10) than other treatments combined (14/23), although samples sizes were small. The results of a second similar trial provided additional support for this observation. Bats vaccinated orally or by injection with RCN-CAL and RCN-SP survived Pd challenge at a significantly higher rate (P = 0.01) than controls. Using RT-PCR and flow cytometry, combined with fluorescent in situ hybridization, we determined that expression of IFN-γ transcripts and the number of CD4 + T-helper cells transcribing this gene were elevated (P < 0.10) in stimulated lymphocytes from surviving vaccinees (n = 15) compared to controls (n = 3). We conclude that vaccination with virally-vectored Pd antigens induced antifungal immunity that could potentially protect bats against WNS.

Scientific Reports↗

USGS1998

Vaccination of rainbow trout against infectious hematopoietic necrosis (IHN) by using attenuated mutants selected by neutralizing monoclonal antibodies

A neutralizing monoclonal antibody against infectious hematopoietic necrosis virus (IHNV) was used to select neutralization-resistant mutants from isolates of virus obtained from adult steelhead Oncorhynchus mykiss returning to the Round Butte Hatchery (RB mutants) on the Deschutes River in Oregon, USA, and from rainbow trout (nonanadromous O. mykiss) at a commercial hatchery in the Hagerman Valley of Idaho, USA (193-110 mutants). Two of the mutants, RB-1 and 193-110-4, were significantly (P < 0.001) attenuated compared with parental strains. Vaccination of rainbow trout by waterborne exposure to the mutants conferred solid protection against challenge with wild-type virus. In some trials, fish vaccinated with the RB-1 mutant at 50% tissue culture infectious doses (TCID50) of 1 X 104-1 x 105 TCID50/mL or with the 193-110-4 mutant at 1 x 102-1 x 103 TCID50/mL, held for 14 d, then challenged with the homologous wild-type strain at 1 x 105 TCID50/mL showed relative percent survival of 95-100% (P < 0.005). There was no significant difference (P > 0.05) in protection among fish exposed to the RB-1 vaccine strain at a dose of 1 x 105 TCID50/mL for periods of either 1, 12, or 24 h, held for 14 d, and then challenged with the wild-type RB isolate, although the 1-h exposure seemed to be somewhat less effective. Fish were vaccinated with the RB-1 strain at 1 x 103-1 x 105 TCID50/mL for 24 h then challenged after 1, 7, 14, or 21 d with the wild-type RB isolate. No significant (P > 0.1) protection was observed at 1 d postvaccination, but the relative percent survival increased progressively at each subsequent challenge period, becoming statistically significant by day 7 (P < 0.001) and beyond. These results suggested that resistance to challenge with wild-type virus resulted from development of IHNV-specific immunity and not from viral interference or interferon induction, and they reinforce the potential of an attenuated vaccine to control this important disease.

Journal of Aquatic Animal Health↗

USGS2001

Antibody response to rabies vaccination in captive and freeranging wolves (Canis lupus)

Fourteen captive and five free-ranging Minnesota gray wolves (Canis lupus) were tested for the presence of rabies virus neutralizing antibodies (RVNA) after vaccination with an inactivated canine rabies vaccine. Blood was collected from all wolves prior to vaccination and at 1 mo postvaccination (PV) and from all captive and three wild wolves at 3 mo PV. In addition, one free-ranging wolf was sampled at 4 mo PV, and two free-ranging wolves were sampled at 6 mo PV. All wolves were seronegative prior to vaccination. RVNA were detected in 14 (100%) captive wolves and in four of five (80%) free-ranging wolves. The geometric mean titer of the captive wolves at 1 mo PV was significantly higher (P = 0.023) than in the free-ranging wolves. Five of 13 (38.5%) captive wolves and none of the three (0%) free-ranging wolves had measurable RVNA at 3 mo PV. No measurable RVNA were detected in the serum samples collected from the free-ranging wolves at 4 and 6 mo PV. These results should be interpreted with caution because of the small number of free-ranging wolves tested. Further research is needed to properly assess immune function and antibody response to vaccination in captive wolves in comparison with their free-ranging counterparts.

Journal of Zoo and Wildlife Medicine↗

USGS2006

Vaccination as a potential means to prevent plague in black-footed ferrets: Progress and continuing challenges

This study was conducted to further assess the feasibility of vaccinating black-footed ferrets ( Mustela nigripes ) against plague (caused by the bacterium Yersinia pestis ). On days 0 and 28, 17 postreproductive ferrets were immunized by subcutaneous injection with a recombinant fusion protein containing F1 and V antigens from Y. pestis. Another 17 animals received a placebo by the same route. Two weeks after the second immunization, mean antibody titers to Y. pestis F1 and V antigens were measured and found to be significantly higher in vaccinates than their preimmunization values (P < 0.0001) and significantly higher than the control values (P < 0.0001). Six months postimmunization, 16 vaccinates and eight controls were challenged with approximately 8,000 colony forming units of virulent plague by subcutaneous inoculation. Eleven of 16 vaccinates (69 percent) survived with no ill effects whereas all eight control animals died within 3a??6 days. Two months later, the 11 surviving vaccinates were challenged again by ingestion of a plague-infected mouse. None of the animals showed any ill effects and all survived. In contrast, seven control ferrets fed infected mice died within 2a??4 days, including one animal that did not actually ingest the mouse but was likely exposed to it. This study demonstrates that immunization of ferrets with the recombinant F1-V fusion protein can induce significant antibody responses and reduce their susceptibility to plague infection.

Scientific Investigations Report↗

USGS2005

A cohabitation challenge to compare the efficacies of vaccines for bacterial kidney disease (BKD) in chinook salmon Oncorhynchus tshawytscha

The relative efficacies of 1 commercial and 5 experimental vaccines for bacterial kidney disease (BKD) were compared through a cohabitation waterborne challenge. Groups of juvenile chinook salmon Oncorhynchus tshawytscha were vaccinated with one of the following: (1) killed Renibacterium salmoninarum ATCC 33209 (Rs 33209) cells; (2) killed Rs 33209 cells which had been heated to 37??C for 48 h, a process that destroys the p57 protein; (3) killed R. salmoninarum MT239 (Rs MT239) cells; (4) heated Rs MT239 cells; (5) a recombinant version of the p57 protein (r-p57) emulsified in Freund's incomplete adjuvant (FIA); (6) the commercial BKD vaccine Renogen; (7) phosphate-buffered saline (PBS) emulsified with an equal volume of FIA; or (8) PBS alone. Following injection, each fish was marked with a subcutaneous fluorescent latex tag denoting its treatment group and the vaccinated fish were combined into sham and disease challenge tanks. Two weeks after these fish were vaccinated, separate groups of fish were injected with either PBS or live R. salmoninarum GL64 and were placed inside coated-wire mesh cylinders (liveboxes) in the sham and disease challenge tanks, respectively. Mortalities in both tanks were recorded for 285 d. Any mortalities among the livebox fish were replaced with an appropriate cohort (infected with R. salmoninarum or healthy) fish. None of the bacterins evaluated in this study induced protective immunity against the R. salmoninarum shed from the infected livebox fish. The percentage survival within the test groups in the R. salmoninarum challenge tank ranged from 59% (heated Rs MT239 bacterin) to 81 % (PBS emulsified with FIA). There were no differences in the percentage survival among the PBS-, PBS/FIA-, r-p57-and Renogen-injected groups. There also were no differences in survival among the bacterin groups, regardless of whether the bacterial cells had been heated or left untreated prior to injection. ?? Inter-Research 2005.

Diseases of Aquatic Organisms↗