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Imprint
Measures against virus diseases in organic aquaculture
Project
Project code: 2810OE053
Contract period: 01.11.2010
- 31.10.2014
Budget: 219,083 Euro
Purpose of research: Applied research
Within the project the influence of different disinfection strategies for dealing with ecological fish farms after outbreaks of diseases caused by koi herpesvirus (KHV) and viral haemorrhagic septicaemia virus (VHSV) should be investigated. Due to the fact that sediments have been believed to act as virus reservoirs, the main focus was directed to the vi-rus adsorbed on them. In order to achieve this goal, sufficient virus concentrations had to be provided allowing appropriate realization and documentation of disinfection experiments. Up to the date, no such titers had been reported for KHV. Consequently, an optimization of the in vitro KHV replication was the basic requirement. For evaluation of the infection, dilution techniques had to be established in order to provide reliable quantification of infective particles. As a result, experiments of virus adsorption onto selected materials and the influence of ecological disinfectants in solution as well as on adsorbed virus could be accomplished.
By means of optimization of the virus-host system, titers of KHV, such as 1 x 108 plaque-forming units (PFU) per mL, could be reached, enabling inactivation studies on both viruses. At first, minimal concentrations of burnt lime and peracetic acid resulting in a com-plete inactivation of both viruses in suspension could be determined as 10 mmol/L and 0.1 vol.-%, respectively. The shifting of the pH-level of the solution down to 4.5 and up to 12 also showed to be very effective. The analyses of 87 ponds show a pH-level of the soil in a range of 4,8 to 7,8. In the case of very low pH level no disinfection will be needed re-spectively the disinfection with peracetic acid is preferable to the application of lime. Ad-ditionally, a protease (Neutrase®) was considered as a promising disinfectant with con centrations of 8 U/L leading to complete inactivation of 1 x 106 PFU/mL of virus. Finally, established germicides were also successfully applied to adsorbed viruses on solid material.
The investigation of virus stability leads to the presumption that a combination of factors, such as light, temperature and especially proteases produced by microorganisms in natural ponds, are sufficient to inactivate viruses in water as well as in sediments. Consequently, it is most important to make sure, that no further reservoirs such as latent hosts or other known carriers stay behind after having removed diseased fish. Because of resistivity against freeze-thawing cycles of both viruses and considerably decelerated disinfection processes at cool temperatures, all strategies should take place during summer.
Section overview
Subjects
- Animal health
- Pond fisheries
- Organic Farming
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
