Defying the koi herpes virus

With the help of the improved diagnostics, infected animals can be reliably identified and separated from healthy ones.

Around half of all fish today come from aquaculture, since the overfishing of the oceans has caused this market to grow steadily. For fishery yield, the health of the fish is crucial.

After the trout, the carp is the most important aquaculture fish in Germany. Large carp farms can be found in the Saxon Upper Lusatia area, although Franconia and the Upper Palatinate are also considered traditional carp regions with numerous smaller farms. For years, breeders across Germany have been fighting against the koi herpes virus that is continuing to spread and causing the notifiable KHV infection. During an outbreak of the disease in Saxony from 2003 to 2005, nearly all the animals died in some fish farms; 28 tons of carp were lost.

Improved diagnostics using cell cultures

“The KHV infection cannot be treated, so it is important to prevent it as far as possible. Together with our project partners, we have developed improved diagnostics with which infected animals can be identified reliably. The more quickly the sick carp are separated, the greater the chance is of protecting the other fish from KHV,” says Dr. Sebastian Rakers, who heads the working group Aquatic Cell Technology and Aquaculture at the Fraunhofer Research Institution for Marine Biotechnology and Cell Technology EMB in Lübeck, Germany.

Previously, the koi herpes virus had been detected by PCR tests that made the pathogen DNA visible in a tissue sample. “If not enough virus DNA is present in the sample, though, you get false negative results with PCR.”

Another significant disadvantage of the PCR tests: they do not allow a conclusion to be reached about how infectious the virus is, since the genomic evidence does not necessarily correspond with the detection of reproducible virus.

“With our improved and somewhat newly developed methods using cell cultures, we can determine how many virus particles are present per cell – therefore, also how strongly the virus is replicated in the cells.” As a result, the cell cultures serve not only as an additional diagnostic tool, but also to understand the virus more thoroughly.

Vaccine development is well on its way

Rakers and his team have managed to grow cell cultures that can replicate significantly more viruses per cell than can traditional cultures. “So far, the best possible titer, which is the number of infectious viruses per milliliter that is needed to kill half of the cells, was 106. We have been able to increase the virus titer to 108, and through further optimization measures, we hope to reach a titer of 1010.”

This is not only important for improved diagnostics; it is also a prerequisite for the development of a highly-effective vaccine against KHV. “Our project partners from the Friedrich Loeffler Institute (FLI), the Chair of Bioprocess Engineering at the Friedrich Alexander University of Erlangen-Nuremberg and the University of Veterinary Medicine Hanover are working intensively on vaccine development and have already been able to significantly reduce mortality in the Asian KHV line.”

The joint project “KHV-Vacc” is funded by the German Federal Ministry of Nutrition and Agriculture (BMEL), due to a decision of the German Bundestag concerning the Federal Institute for Agriculture and Food (BLE), Project Number 2815HS011.

https://www.fraunhofer.de/en/press/research-news/2018/March/defying-the-koi-herp…

Media Contact

Dr. Sandra Schumann Fraunhofer Forschung Kompakt

All news from this category: Agricultural and Forestry Science

Back to the Homepage

Comments (0)

Write comment

Latest posts

Bringing atoms to a standstill: NIST miniaturizes laser cooling

It’s cool to be small. Scientists at the National Institute of Standards and Technology (NIST) have miniaturized the optical components required to cool atoms down to a few thousandths of…

Record-breaking laser link could help us test whether Einstein was right

Scientists from the International Centre for Radio Astronomy Research (ICRAR) and The University of Western Australia (UWA) have set a world record for the most stable transmission of a laser signal through…

Adaptive optics with cascading corrective elements

A cascaded dual deformable phase plate wavefront modulator enables direct AO integration with existing microscopes–doubling the aberration correction range and greatly improving image quality. Microscopy is the workhorse of contemporary…

Partners & Sponsors

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close