Vaccination against VHS in rainbow trout: Experiments and perspectives related to practical fish farming

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1 Vaccination against VHS in rainbow trout: Experiments and perspectives related to practical fish farming Niels Lorenzen Danish Institute for Food and Veterinary Research

2 Nv ~ non-structural protein

3 Topics Traditional VHS vaccines DNA vaccines Principle Safety Results from the lab Testing under fish farm conditions What is the origin of VHS?

4 Bacterial vaccines are produced by fermentation in simple growth substrate. Bacteria in substrate Fermentation

5 Vaccines against viruses?

6 Vaccines against viruses Traditional vaccines: Inactivated virus or attenuated virus - usually too expensive or not safe enough for aquaculture

7 DNA vaccines: the principle Virus particle Surface protein (G) Gene cloning Vaccine plasmid Vaccination De bedøvede fisk vaccineres med plasmid i rygmuskularturen

8 DNA vaccines: the principle Virus particle Surface protein (G) Gene cloning Vaccine plasmid Purification E.coli Vaccination Fermentation De bedøvede fisk vaccineres med plasmid i rygmuskularturen Plasmid DNA is easy to produce in bacteria

9 DNA vaccines: the principle Virus particle Surface protein (G) Gene cloning Vaccine plasmid E.coli Purification of plasmid Vaccination GMO Fermentation De bedøvede fisk vaccineres med plasmid i rygmuskularturen Not GMO

10 DNA vaccination: Princip Virus particle Surface protein (G) Gene cloning Vaccine plasmid Fermentation + Purification Vaccination by Intramuscular injection

11 DNA vaccination of fish: intramuscular injection

12 Production of VHSV G-protein in fish cells Transport to cell surface Fish cell

13 Muscle of fish vaccinated with overdose of DNA vaccine -3 weeks after vaccination - E. Lorenzen et al. Fish Shellfish Immunol.( 2005) 19:27-41

14 -5 weeks after vaccination - E. Lorenzen et al. Fish Shellfish Immunol.( 2005) 19:27-41

15 Advantages of DNA vaccines High safety no risk of disease, no GMO Rapid and long-lasting protection High stability Simple to procedure

16 Disadvantages of DNA vaccines Injection vaccination not practical for small fish. Licensing/commercialisation complicated/expensive. Consumers acceptance important (in some countries).

17 Challenge experiments with DNA-vaccinated fish in the laboratory

18 Challenge of vaccinated fish VHS virus

19 Efficacy of the VHS DNA vaccine when tested in rainbow trout fingerlings at 12 C: Time-course Specificity

20 Time-course study Based on E. Lorenzen et al J. Aquat. Anim. Health. 12, , cumulative mortality (%) days post challenge 8d,vhsG 19d,vhsG 28d,vhsG 61d,vhsG 112d,vhsG 168d,vhsG 168d,pcDNA3

21 Time-course of protection following DNA vaccination against VHSV and IHNV RPS IFN Antibody Weeks Non-specific post vaccination mechanisms Specific mechanisms Total protection Weeks post Vaccination 106 N Lorenzen et al. Fish & Shellfish Immunology (2002) 12:

22 The VHS DNA vaccine protects turbot against nodavirus challenge 8 days post vaccination 60 Cumulative mortality (%) pvhsv-g pcdna3.1(contr.) pahnv-c Time post challenge (days) Sommerset et al, Vaccine, 2003

23 Conclusions : The VHS DNA vaccine induces early non-specific as well as long-lasting specific protection. The VHS DNA vaccine seems to have an adjuvant- like effect

24 Field trial Experimental setup Vaccination at two different VHS-free farms

25 Field trial Experimental setup Vaccination at two different VHS-free farms Transfer of vaccinated fish to net-cages on farms with clinical VHS.

26 Collaborative project DFVF Danish Aquaculture Association GeneCare The Danish Veterinary and Food Administration Supported by Danish Ministry of Food, Agriculture and Fisheries The Henriksen Foundation

27 Results from field-challenge with VHS: High variability among cages: - high survival of vaccinated fish in some cages - high mortality of all fish in other cages (other diseases than VHS)

28 Conclusions The DNA vaccine works under field conditions but does not protect against other diseases. Experimental setup with net cages is not optimal. Next experiment should include vaccination of all fish in several ponds or all fish on selected farms in endemic zones.

29 VHS Dansk Akvakultur First observation in Denmark in : 520 Farms infected 2004: 41 Farms infected

30 In Denmark, the strategy is still VHS-eradication by Stamping-out Very important to avoid re-introduction of virus

31 What is the origin of VHS virus?

32 VHS virus has been found more than 70 marine fish species Based on Skall et al J Fish Dis Sep;28(9):509-29

33 VHS in Europe might originate from the Baltic Sea

34 EU US III 62 IV 500 years Who was the ancestor of VHSV in Europe? years 50 years 50 years EU II 9 EU K. Einer-Jensen et al. J Gen Virol. (2004) 85: I DK DK DK DK DK DK DK DK DK DK DK DK DK DK DEFil DK3592B-1986 DK DK DK DK DK FR AU CHFC DK DK FR FR FR DK6p SESVA SESVA UKMLA986H DK4p SESVA SESVA DK5e UK DK1p DK1p DK1p DKMrhabdo-1979 DK DK DK DKHededam-1972 DKF FIka FIka NOA16368G-1968 GE UKH UKMLA986P UKH DK4p IRF DK4p FRL UK DK1p DK1p I III USMakah-1988 IV II

35 In order to avoid VHS: Always be careful when fish are moved from one place to another!

36 Acknowledgements European Commission The Danish Ministry for Food, Agriculture and Fisheries The Henriksen Foundation