PROJECT NUMBER
•
2022-079
PROJECT STATUS:
CURRENT
ORGANISATION:
CSIRO Agriculture and Food Brisbane
SPECIES
3 results
APFA IPA: RNAi treatment of broodstock to reduce disease impacts in farmed prawns
Project number:
2015-240
Project Status:
Completed
Budget expenditure:
$150,000.00
Principal Investigator:
Melony J. Sellars
Organisation:
CSIRO Agriculture and Food Brisbane
Project start/end date:
7 Jun 2016
-
27 Feb 2018
Contact:
FRDC
With the exception for one farm, the Australian prawn farming industry remains reliant on the use of wild broodstock in hatcheries to generate seed to stock farm ponds,. Due partly to problems with GAV often occurring at high prevalence in North Queensland (NQ) (eg. Etty Bay, Bingil Bay, Bramston Beach, Yorkeys Knob), GAV-free broodstock have increasingly been sought from more remote locations in the Northern Territory (NT) (eg. Joseph Bonaparte Gulf and Melville/Tiwi Island) (Cowley et al. 2016).
Broodstock pairs (male + female) typically cost ~$160 when sourced locally from NQ and ~$600 when sourced from NT. Hatcheries use in the order of 3,000 wild-caught broodstock pairs annually. Thus due to (i) the substantially higher costs of broodstock sourced from remote regions in NT, (ii) the detection of a GAV variant designated Yellow head virus genotype 7 (YHV7) amongst NT stock (Cowley et al. 2016) with commercially relevant pathogenic potential (CSIRO Unpublished data) and (iii) difficulties in supply continuity and transport stress, the use of a hatchery-based RNAi strategy to reduce or clear GAV infection from local NQ broodstock with potential to abrogate or curtail the vertical transmission of GAV to progeny would significantly benefit industry.
Proof-of-concept obtained in this project that RNAi can be up-scaled from experimental to hatchery-scale systems, and that progeny with markedly reduced GAV infection loads can be generated from carrier broodstock injected with dsRNA, will provide industry with the confidence needed to apply the technology commercially once an APVMA permit has been issued for its use.
1. Knowledge of the ability of antivirals to abrogate vertical transmission of GAV from parents to progeny.
2. Knowledge of the heightened growth, survival and health performance of progeny from parents that received the antiviral compared progeny from parents that did not receive the antiviral, when reared under commercially comparable pond conditions.
Report
ISBN:
978-0-646-98999-0
Authors:
Melony J Sellars
Min Rao
Brian S Murphy
Jeff A Cowley
Report
•
2018-02-01
•
1.51 MB
2015-240-DLD.pdf
Reported here are the outcomes of a project with original objectives to assess (i) the ability of injected double-stranded (ds)RNA antivirals to reduce Gill-associated virus (GAV) infection loads in Black Tiger prawn (Penaeus monodon) broodstock and whether this can (ii) reduce GAV infection prevalence/loads in progeny and (iii) result in improved growth performance and survival of progeny reared in research ponds under simulated commercial conditions.
As these project objectives were revised due to difficulties in sourcing wild broodstock infected with suitably high loads of GAV, also reported are data from agreed alternative project objectives showing that (i) Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is transmitted vertically from infected female broodstock to progeny and that the IHHNV prevalence and infection loads in progeny are influenced by infection loads in their parental female and (ii) the high-load infections that develop in progeny spawned from females with higher-level IHHNV infection result in substantially reduced growth performance and survival of progeny reared in 0.16 ha ponds under simulated commercial conditions.
The screening of batches of wild P. monodon broodstock to identify locations where these might be infected with GAV at moderately-high loads suitable for the original project objectives identified GAV to be present at very low prevalence among prawns captured at various locations in the vicinity of Innisfail between May and June 2016. Similar screening also identified the absence of Yellow head virus genotype 7 (YHV7) in these broodstock.
Further to these objectives and data, it was agreed to include another project variation objective to investigate whether (i) dsRNA(s) injected into tail-muscle of female broodstock at the time eyestalks were ablated to induce ovary maturation/spawning could be detected by TaqMan real-time RT-qPCR in various tissues (i.e. pleopod, ovary and lymphoid organ) several days later when the female spawned and (ii) dsRNA might transfer from injected females to spawned eggs and be maintained or amplified through larval life stages (i.e. nauplii, protozoea, mysis) to an early post-larvae (PL) stage
As these project objectives were revised due to difficulties in sourcing wild broodstock infected with suitably high loads of GAV, also reported are data from agreed alternative project objectives showing that (i) Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is transmitted vertically from infected female broodstock to progeny and that the IHHNV prevalence and infection loads in progeny are influenced by infection loads in their parental female and (ii) the high-load infections that develop in progeny spawned from females with higher-level IHHNV infection result in substantially reduced growth performance and survival of progeny reared in 0.16 ha ponds under simulated commercial conditions.
The screening of batches of wild P. monodon broodstock to identify locations where these might be infected with GAV at moderately-high loads suitable for the original project objectives identified GAV to be present at very low prevalence among prawns captured at various locations in the vicinity of Innisfail between May and June 2016. Similar screening also identified the absence of Yellow head virus genotype 7 (YHV7) in these broodstock.
Further to these objectives and data, it was agreed to include another project variation objective to investigate whether (i) dsRNA(s) injected into tail-muscle of female broodstock at the time eyestalks were ablated to induce ovary maturation/spawning could be detected by TaqMan real-time RT-qPCR in various tissues (i.e. pleopod, ovary and lymphoid organ) several days later when the female spawned and (ii) dsRNA might transfer from injected females to spawned eggs and be maintained or amplified through larval life stages (i.e. nauplii, protozoea, mysis) to an early post-larvae (PL) stage
Aquatic Animal Health Training Scheme - Training for prawn farmers in sample collection
Project number:
2009-315.34
Project Status:
Completed
Budget expenditure:
$2,000.00
Principal Investigator:
Melony J. Sellars
Organisation:
CSIRO Agriculture and Food Brisbane
Project start/end date:
30 Apr 2015
-
30 Aug 2015
Contact:
FRDC
Training prawn hatchery/farm staff in collecting samples was identified as a priority need in FRDC Project No. 2012/030 (Prawn Superpowers Summit – enhancing awareness of emergency aquatic animal disease response arrangements for the Australian prawn farming industry, Matt Landos and Helen Jenkins, March 2013).
Further consultation this year (2015) with the APFA, Industry members, the Queensland Department of Agriculture and Fisheries (QDAF), the CSIRO Agriculture Flagship and the newly established Australian Research Council (ARC) Research Hub for Advanced Prawn Breeding coordinated by James Cook University (JCU) have reaffirmed the need for a hands-on training workshop. These parties have identified that such a workshop should cover a refresher on Emergency Response procedures including prawn sampling requirements and procedures as well as prawn sampling needs and procedures for prawn pedigree analysis and viral screening to fulfil the needs of breeding programs.
1. Training workshop for prawn farmers in sample collection.A 3 h workshop with hands-on training components will be run for prawn farmers that will include:• A refresher on Emergency Response procedures• Emergency Response prawn sampling requirements and procedures• Prawn sampling needs and procedures for prawn pedigree analysis and viral infection screening as part of breeding programs• Provision of detailed sampling protocols and prawn dissection kits• Hands-on demonstrations followed by participant practice in prawn dissection and tissue sampling and preservation for PCR and histology to meet Emergency Response needs and procedural requirements• Hands-on demonstrations followed by participant practice in prawn dissection and tissue sampling and preservation for PCR-based pedigree analysis and viral screening to meet breeding program needs• Provision of postage and courier procedures and a list of QDAF and CSIRO/JCU contacts • Attendee feedback questionnaire
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