DNA Vaccination Against IHN Virus: A Disease of Trout and Salmon

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1 DNA Vaccination Against IHN Virus: A Disease of Trout and Salmon Scott E. LaPatra Clear Springs Foods, Inc., Research Division, Buhl, Idaho, U.S.A.

2 Infectious Hematopoietic Necrosis Virus (IHNV) Family: Rhabdoviridae (VSV, Rabies) Genus: Novirhabdovirus I N M-1 M-2 G NV L tr ~ 11 kb

3 IHN VIRUS L G N M-1 M-2 SDS-PAGE IHNV

4 Comparison of Prototype IHNV Vaccines Bath Exposure Concentration (PFU/ml) Vaccine 100,000 1,000 0 Attenuated B-Prop-Killed G-subunit Subunit control DNA-G DNA control Native G Baculovirus G Baculovirus ISCOM G ISCOM control PBS

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9 Protective Immunogenicity of IHNV Proteins Summary DNA Vaccine Cumulative Mortality (%) pcdna-g 0-2 pcdna-n 76 pcdna-p 47 pcdna-m 50 pcdna-nv 66 pcdna-b gal pcdna buffer 58-66

10 DNA Vaccine Dose Determination Host Size Vaccine Dose (ug) RPS (%) Exp. 1 RPS (%) Exp nd Fry ( g) nd 61 Sub-Yearling ( g) nd 0

11 Efficacy of Different Routes of Vaccination pluc pwg NT Cumulative % Mortality * * * IM Beads Gene gun IP Skin IB Scarification No Treatment

12 Protection Against Heterologous IHNV Strains pluc pwg Cumulative % Mortality Mock Wrac AK14 RB1 Col85 Shizuoka Fr3287 *

13 The Duration of Protection of the IHNV DNA Vaccine Rainbow Trout (mean wt. 2.5 g, 0.1 ug dose) pihnv-g pcdna-luc Cumulative % Mortality g / 3 mos. 37 g / 6 mos. 100 g / 12 mos. 483 g / 24 mos. Size / Age

14 Onset of Protection by the IHNV DNA Vaccine Cumulative % Mortality pihnv-g pihnv-n pcdna-luc Buffer Unhandled

15 Onset and Specificity Studies EAVR Rapid Onset, 4 14 days, Low Specificity Interferon? SAVR Slower Onset, 28 days, High Specificity Antibody?

16 Cross Reactive Protection Induced by the VHS and IHN DNA Vaccines Vaccine Construct Challenge VHSV IHNV 4-7 d pv 1-2 mo pv 4-7 d pv 1-2 mo pv pvhs-g pihn-g plasmid vector Protection with RPS values between 54 and 100 is indicated by + Lack of protection with RPS between 0 and 23 is indicated by -

17 Innate Immunity Elicits Adaptive Immunity RPS Weeks post vaccination Non-specific mechanisms Specific mechanisms Total protection

18 Finfish Aquaculture in British Columbia

19 Typical IHN Mortality Curve peak mortality 6-8 weeks post-onset, to weeks generally over similar across all affected age groups steep increase indicates a large scale point source of infection or highly contagious among population once few become infected Saksida, S. (2003)

20 Infectious Hematopoietic Necrosis in British Columbia, Canada IHN - disease occurring in the marine environment - clinical signs somewhat different not a unique strain of IHNV endemic in wild BC Pacific salmon (adult sockeye salmon - carriers) Altantic salmon very susceptible (~95% BC farmed fish Atlantics)

21 DNA Vaccination of Atlantic Salmon Against IHNV Traxler et al., 1999 Immersion Challenge Treatment Pre-Smolts Smolts Uninjected 78% 50% PBS 45% 50% pcmv-luc 50% 35% pcmv4-g 3% 5%

22 Environmental Assessment for Field Testing of a Veterinary Biologic Produced through Biotechnology Molecular and Biological Characteristics Human Safety Animal Safety Affected Environment Environmental Consequences Monitoring

23 Special Safety Aspects of a DNA Vaccine for Atlantic Salmon Systemic Distribution of Plasmid and Plasmid Clearance Rate 99.5% of plasmids dissipated from inject site by 35 dpv; only trace amounts (<270 copies/ µg gdna) by 728 dpv Not detectible in head kidney, gut lumen gonad, liver, spleen 7 dpv

24 Special Safety Aspects of a DNA Vaccine for Atlantic Salmon Genomic Integration Studies Non-quantifiable levels of plasmid (<50 copies/ μg gdna) in muscle tissue from injection site Signified that occurrence of an integration event highly unlikely

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26 Special Safety Aspects of a DNA Vaccine for Atlantic Salmon Examination of the Potential of Plasmid DNA Transfer to Intestinal Microbial Flora Feces cultured for microorganisms from vaccinated (40) and unvaccinated (10) fish 109 and 58 Kan+ microorganisms isolated from respective fish Resistance not due to vaccine

27 Does Concurrent Administration of Bacterins Affect the Efficacy of IHNV Plasmid Vaccines? Study Compared Efficacy of APEX IHN When Administered Jointly or Separately with Lipogen-Forte Fish vaccinated with APEX showed complete protection Joint administration exhibited low mortality and high protection Bacterin administration before or after APEX gave higher mortality

28 APEX IHN Clinical Field Trail in British Columbia, Canada Three Freshwater Atlantic Salmon Hatcheries 1.6 million APEX IHN Lipogen Forte 271,877 Lipogen Forte No Difference in Mortality (0.11%) Confirming Safety at 10 ug dose (0.05 ml) No Clinical IHNV Occurred but Antibody + Laboratory Trials Confirmed Efficacy

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30 Frankenfish

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34 Site of DNA Vaccine Delivery Effect on EAVR and SAVR Cumulative % Mortality d.p.v. 28 d.p.v. Head Normal Dorsal Caudal Vector Controls

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