Novel RNA viruses causing muscle lesions in red claw crayfish (Cherax quadricarinatus)
Sakuna, Kitikarn (2018) Novel RNA viruses causing muscle lesions in red claw crayfish (Cherax quadricarinatus). PhD thesis, James Cook University.
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Abstract
In 2014, a new syndrome was recognized in redclaw crayfish (Cherax quadricarinatus) from farms in northern Queensland. Crayfish started to die with mortality reaching 40% in approximately three weeks after transportation and translocation stress. In trying to identify the cause of the disease, sequence dependent and independent PCRs failed to identify any aetiology. However, using next gen sequencing of RNA, two novel RNA viruses, namely chequa iflavirus and bunya‐like virus were found in the stressed, dying crayfish. Chequa iflavirus is a positive sense, single stranded RNA virus in the order Picornavirales, marginally in the genus Iflavirus. This is the first iflavirus identified from crustracea. The bunya‐like virus found is related to Whenzhou Shrimp Virus 2, a bi‐segmented, unaligned, negative sense, single strand RNA virus. Efficient and sensitive detection methods for these viruses based on RNA dependent RNA polymerase (RdRp) was developed for large scale screening of crayfish on farm. Due to a lack of virus‐free crayfish, house cricket, Acheta domesticus was trialled as a bioassay animal to prove River’s postulates for chequa iflavirus and bunya‐like virus. However, it was unsuccessful as the immune system of cricket might able to destroy and leave no viable virus or enough traces of RNA to be detected by reverse transcription polymerase chain reaction (RT‐PCR). To solve the viral infection problem with chequa iflavirus infection on farm, some possible viral reduction strategies for farmers were trialled. The polyphenol flavonoid quercetin, inhabiting water temperature at 32°C all had statistically significant effects reducing viral copy numbers (P<0.018; P<0.05 respectively). While RNA interference based on RdRp sequence appeared to drop viral copy number 80% at four weeks, it was not statistical significant (P˃0.05). For the crayfish farmers, quercetin is the most favoured treatment as it is abundant, cheap and readily incorporated into the diet and should ameliorate the original, transport‐stress mortality which started this study. Broodstock could be warmed to 32°C in the hatchery to reduce viral dose. Although RNAi treatment was most expensive to implement, it could be delivered with limited amounts of RNAi at the hatchery.
| Item ID: | 63103 |
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| Item Type: | Thesis (PhD) |
| Keywords: | bunya-like virus, Bunyavirales, Chequa iflavirus, Cherax quadricarinatus, crickets, Iflavirus, Picornavirales, quercetin, redclaw crayfish, RNAi, RT-LAMP, RT-qPCR, stress, stressed, temperature |
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| Copyright Information: | Copyright © 2018 Kitikarn Sakuna. |
| Additional Information: | Five publications arising from this thesis are stored in ResearchOnline@JCU. Please see the Related URLs field. The publications are: Appendix C1 / Chapter 4: Sakuna, Kitikarn, Elliman, Jennifer, and Owens, Leigh (2017) Discovery of a novel Picornavirales, Chequa iflavirus, from stressed redclaw crayfish (Cherax quadricarinatus) from farms in northern Queensland, Australia. Virus Research, 238. pp. 148-155. Appendix C2 / Chapter 5: Sakuna, Kitikarn, Elliman, Jennifer, and Owens, Leigh (2018) Comparison of molecular detection PCR methods for chequa iflavirus in freshwater crayfish, Cherax quadricarinatus. Journal of Virological Methods, 251. pp. 139-144. Appendix C3 / Chapter 6: Sakuna, Kitikarn, Elliman, Jennifer, and Owens, Leigh (2017) Assessment of a cricket, Acheta domesticus, bioassay for Chequa Iflavirus and bunya-like virus from redclaw crayfish Cherax quadricarinatus. Journal of Invertebrate Pathology, 150. pp. 41-44. Appendix C4 / Chapters 4 and 5: Sakuna, Kitikarn, Elliman, Jennifer, Tzamouzaki, Anna, and Owens, Leigh (2018) A novel virus (order Bunyavirales) from stressed redclaw crayfish (Cherax quadricarinatus) from farms in northern Australia. Virus Research, 250. pp. 7-12. Appendix C5 / Chapter 7: Sakuna, Kitikarn, Elliman, Jennifer, and Owens, Leigh (2018) Therapeutic trials against pre-existing Chequa iflavirus in redclaw crayfish (Cherax quadricarinatus). Aquaculture, 492. pp. 9-14. |
| Date Deposited: | 14 May 2020 23:45 |
| FoR Codes: | 06 BIOLOGICAL SCIENCES > 0605 Microbiology > 060506 Virology @ 35% 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070401 Aquaculture @ 35% 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070404 Fish Pests and Diseases @ 30% |
| SEO Codes: | 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8301 Fisheries - Aquaculture > 830101 Aquaculture Crustaceans (excl. Rock Lobster and Prawns) @ 80% 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 20% |
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