Transcript Document

Characterisation of the antiviral response
associated with “mass mortalities” of the
Pacific oysters, Crassostrea gigas
Timothy Green, Caroline Montagnani, Nick Robinson,
Kirsten Benkendorff & Peter Speck
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Herpès virus OsHV-I
Vibrio splendidus
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T°C Thau
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Temperature (°C)
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Date
Pernet et al., 2013
28/06
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31/05
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Mortalité cumulée (%)
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Survival - why do oysters die?
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IFN-like pathway in Oysters?
Green & Montagnani 2013
Oysters have a complex antiviral
immune repertoire!!!
Green et al.,
Within-Generation Immune Priming
Poly I:C: synthetic dsRNA, which mimics a virus.
Results: Trial I
Results: Trial II
Conclusion
• dsRNA (poly I:C)
induces C. gigas into an
antiviral state.
• Oyster possess a
specific and inducible
innate antiviral
response.
Control Measures for POMS
• Farm management/husbandry
o Gagnaire et al., 2006; Peeler et al., 2012; Pernet et al., 2012;
Paul-Pont et al., 2013.
o Successful management requires knowledge: Virus reservoir,
routes of transmission, environmental risk factors, etc.
o Survival cannot be at the detriment of other commercial traits!
Control Measures for POMS
• Farm management/husbandry
o Gagnaire et al., 2006; Peeler et al., 2012; Pernet et al., 2012;
Paul-Pont et al., 2013.
o Successful management requires knowledge: Virus reservoir,
routes of transmission, environmental risk factors, etc.
o Survival cannot be at the detriment of other commercial traits!
• Develop POMS resistant oysters
o Natural selection (> 10 years).
o Translocation of broodstock between jurisdictions.
o Indirect selection?
Control Measures for POMS
• Farm management/husbandry
o Gagnaire et al., 2006; Peeler et al., 2012; Pernet et al., 2012;
Paul-Pont et al., 2013.
o Successful management requires knowledge: Virus reservoir,
routes of transmission, environmental risk factors, etc.
o Survival cannot be at the detriment of other commercial traits!
• Develop POMS resistant oysters
o Natural selection (> 10 years).
o Translocation of broodstock between jurisdictions.
o Indirect selection?
• Trans-generational immune priming
o ?
Evidence of trans-generational
immune priming in invertebrates
Evidence of trans-generational immune
priming in Pacific oysters to OsHV-1
Future Directions
• Questions:
o Does transgenerational priming exist in
Crassostrea gigas?
o Can you prime with a virus associated
molecular pattern (i.e. poly I:C)
o If so, what is the molecular mechanism that
provides increased protection to oyster
progeny?
Inducible antiviral response in
oysters?
Results: Gene expression profiles measured didn’t explain the
reduced viral load in the resistant family line.
Question: Do oysters have an inducible innate immune
response against virus infection?
Plaque-reduction assay as a method for screening antiviral
activity
Vero cells
Vero cells + HSV-1
Vero cells + HSV-1 + oyster 1
Vero cells + HSV-1 + oyster 2
Vero cells
Vero cells + HSV-1
Vero cells + HSV-1
+ oyster 1
Vero cells + HSV-1
+ Oyster 2
Antiviral Activity of Australian
Pacific oyster hemolymph
h2 = 0.21
ASI Family Lines
Identification of oyster antiviral
compound(s)
Why do oysters die?
• Laboratory experiment
1) Treatment (poly I:C verse seawater)
2) Temperature (12 verse 22oC)
3) Development (Adults verse Juvenile)
• Hypothesis:
 Virus relies on faster cell replication rate of juvenile cells.
 Therefore, temperature and developmental stage has no affect on
immune response.
 Alternative hypothesis: oysters at 22oC are immuno-suppressed or
the immune system of juveniles is immature.
Summary/Future Direction
1 Developing a proxy for indirect selection.
2 Why oysters die.
3 Continue investigating trans-generational
priming as a control mechanism.
POMS challenge trials in SA
• POMS challenge model would be advantageous to our
research.
• We have asked SAOGA & PIRSA to conduct a POMS challenge
trials at the physical containment (PC2) facility at Roseworthy.
• We will work with SAOGA & PIRSA to make sure this research
is conducted safely.
• Our research will be overseen by the Flinder’s Institutional
Biosafety Committee.
• We have experience conducting POMS challenge trials.
• We currently use HSV-1 as a surrogate model. Experience with
human viruses.
• Project will build POMS research capacity in SA!!!
• It will be done safely!!!
Acknowledgements
• Seafood CRC (Graham Mair)
• ASI
• NSW Fisheries (Wayne)
• RIME (Julien, Delphine, Agnes)
• IFREMER (La Treblade, Palavas, Sete)
• SAOGA (Trudy)
• PIRSA & SARDI (Shane, Marty & Mehdi)
• Gary Zippel