PD Dr. Anna M. Becker – Control and combat of fish viroses

PD Dr. Anna M. Becker – Application of proteases to control and combat of fish viroses in aquaculture

In the search for new, environmental friendly and sustainable disinfection agents, that could be used after viral infection in fish ponds, proteases and their influence on the infectivity of various enveloped (KHV, VHSV, IHNV) and non-enveloped fish viruses was investigated in this work.

At first, water and soil samples from surrounding fish ponds were analyzed in order to evaluate their quality. Despite relatively wide range of the values of the determined parameters, in average they were normal and compatible with requirements for fish culture.

Investigation of the proteolytic activity of the chosen proteases under various parameters showed sufficiently good activities at environmentally relevant conditions. Moreover, their proteolytic activity decreased rapidly in pond water, thus no measures for inactivation after their use would be necessary and no permanent consequences for the environment are to be expected.

Under laboratory conditions, all investigated here enveloped viruses – KHV, VHSV, IHNV – could be inactivated with examined proteases, though the disinfection was reached most frequently with Neutrase®. Inactivation of the viruses with proteases occurred rapidly and could also be conducted under the pH-values that were determined in this study and/or directly in the pond water samples.

Although in some cases the infectivity of KHV, VHSV and IHNV after addition to unsterile pond water samples rapidly decreased, the speed of inactivation of these viruses in environmental waters can vary, hence, fast and efficient measures for disinfection are still necessary. However, further studies are needed, as shown in this work this can also be reached by the use of proteases.

This project was carried out in close cooperation with researchers from the Friedrich-Loeffler-Institute, the Bavarian State Institute for Agriculture and the Bavarian State Office for Health and Food Safety. It was financed by the Federal Ministry of Agriculture and Food, due to a resolution of the German Bundestag, via the Federal Institute for Agriculture and Food (project number: 2815NA062).

Publications:

Ullrich J, Christian J, Bergmann SM, Oberle M, Becker AM (2021): Stability of viral haemorrhagic septicaemia virus, infectious hematopoietic necrosis virus and cyprinid herpesvirus 3 in various water samples. J Fish Dis, 44(4), 379-390.

Amtmann A, Ahmed I, Zahner‐Rimmel P, Mletzko A, Jordan LK, Oberle M, Wedekind H, Christian J, Bergmann SM, Becker AM (2020): Virucidal effects of various agents – including protease – against koi herpesvirus and viral haemorrhagic septicaemia virus. J Fish Dis, 43(2), 185-195.