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Sturgeons

Sub-family (18 sp.) genus (2)

Sub-family

Risks associated with viruses genre (3) genre (3)

artore

[email protected] S ©J. ©J.

Vietnam Russia Farming

• Caviar (China, Italy, France, etc.) • Flesh • Repopulating: France, Poland, Italy, USA, etc.

Italy USA

Farming sturgeons and viruses

• At least 5 viral families • Limited biological/epidemiological data • Dissemination of viruses favored by: International trade, legal and illegal

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White sturgeon adenovirus Betanodavirus

• Affected juvenile in 1984 (Hedrick 1985) • 50% mortality over 4 months • Nuclei enlarged (epithelial cells of intestine)

• Cell cultured on WSS-2 (Hedrick 1991) • Partially sequenced

• No heard of it since…a while Horizontal transmission, from sea bass to Sturgeon

IHNV Herpesviridae

• Experimental infection of white sturgeon AciHV1 AciHV2 (WSHV1) (WSHV2) SbSHV Herpes ? (Lapatra et al 1995)

1991 1995 2009 2013 Acipenser A. transmontanus A. baeri A. brevirostrum IHNV can replicate in larval white sturgeons but transmontanus California Huso huso x A. ruthenus Canada California (Watson et al.) Russia (La Patra et al.) presumably not in juveniles or adults (Hedrick et al.) (Shchelkunov et al.)

Herpesviridae Herpesviruses are epitheliotropic

Scott Weber Shchelkunov 2009

Fig. 4. Acipenser baeri. (A) Multiple plaques of epidermal proliferation (arrows) in a fingerling of infected with Siberian sturgeon herpesvirus (SbSHV) and (B) haemorrhagic ulceration of the skin and the lateral scutes of the caudal trunk in virus-infected 2 yr old Siberian sturgeon

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Herpesviridae Herpesviridae Genetic diversity (DNA pol)

• Cultivable in vitro, on WSSK-1, SSO-2, SSF-2 • cPCR …to improve • qPCR…to set up

Dozspoly 2013

Herpesviridae Iridoviridae To-do list

• Develop specific diagnostic tests (AciHV1/2) • Screen farms in Europe (all host species)

• Search for other AciHV species with generic MRSIV Namao WSIV Iridovirus (SSIV) (NCLDV) Iridovirus Frog irido 3 tools

1990 1998 2001 2013 2014 2014

Acipenser transmontanus A. gueldenstaedtii Scaphirhynchus albus Acipenser fulvescens Acipenser brevirostrum (2009) USA Europe S. scaphirhynchus Manitoba, Canada Canada (Hedrick) (Adkinson ) (McConnell) (Clouthier) (La Patra)

Iridoviridae diagnostics Iridoviridae diagnostics

• Histology – Basophilic inclusions and enlarged cells in the • PCR  MCP gene integument and gills – cPCR virus-specific or –generic (Clouthier et al; Bigarré et al.)

et et al.

Raverty – qPCR virus-specific (Clouthier et al; Bigarré et al.) Virology Virology Lecture Health Fish Management 424: FISH

• WSIV culturable, not the others

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Iridoviridae ? NCLDV ! A complex epidemiological situation

• Various countries ? – USA, Canada, Europe

• Hosts – Diverse sturgeon species

• A cloud of viruses

– WSIV, SSIV, MRSIV, SNSV, NV, AciV-E.

– 1 iridovirus d’amphibien (FIV3)

Clouthier 2015 Clouthier 2013

Iridoviridae in Europe Iridoviridae In Europe a b c

• One (series of) outbreak in 1998, diagnosed by histology. Possibly Belgium and the Netherlands

• These last years, suspicions on Russian sturgeons d e f

g h

Iridoviridae in Europe Iridoviridae in Europe Development of a generic PCR Testing the method on field samples

. With or without symptoms . Polymicrobism MCP gene (1,3kb)

B A D

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European samples (MCP gene) Positive results

• 4 host species: – Siberian, Russian, , Adriatic

• 3 European countries

• 2 distinct iridoviruses: – AciV-E – NV

A real-time PCR for AciV-E… Intra-sample genetic diversity …nearly validated

Iridoviridae in Europe How do viruses spread ? conclusions • At least 2 distinct viruses, probably of • Infected wild fish used as genitors American origins • Detected • Mix of species in farms – by a same cPCR – by distinct qPCR • Hybrids • Certainly pathogenic, but virulence is host-

dependant…and other factors • International transfers, legal and illegal

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Sturgeon trade (legal) Sturgeon trade (illegal)

Fishermen at Giurgeni bridge, Romania, showing that they offer big fish – which often means sturgeons – for sale © WWF

Conclusions

Thanks to colleagues Conclusions

• Sturgeons viruses are underestimated • Dissemination without control • Urgent need for developing PCR-based diagnostic tools • To prevent dissemination • To shed light on their real virulence

• ‘Iridoviridae’ are a priority. They are widespread: test your fish !

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