BURSARY FUNDS STUDY TO SUPPORT DISEASE RESEARCH IN TROUT SECTOR

Bursary funds study to support disease research in trout sector. MSD Animal Health UK, a division of Merck & Co., Inc., Rahway, N.J., USA (NYSE:MRK) has provided financial support to a PhD student researching the effects of temperature on the development of red mark syndrome (RMS) in rainbow trout. The findings will be significantly beneficial for the aquaculture industry and will help shape the future of trout farming and management.

Massimo Orioles was the first person to be awarded the MSD Animal Health UK aquaculture research bursary in 2020 which was launched alongside new bursaries for the pig and poultry sectors to promote vital research into animal health and welfare.

As a skin disease believed to be caused by a Midichloria-like organism (MLO), RMS typically affects rainbow trout by causing large, red and elevated lesions on the skin as well as possible scale loss. While the disease is not fatal and mortalities due to the disease are not common, the disease can have a negative economic impact due to the fish product being downgraded following the presence of lesions and the requirement for increased treatment and management costs.

To date, the disease has been generally linked with water temperatures below 16°C. But, with no definitive evidence of this, Mr. Orioles’ research project aimed to find answers to this speculation and identify preventative approaches to support the reduction of antibiotic use to treat the disease. Another aim of the study was to see the MLO bacteria inside the lesions in a laboratory environment.

“The project involved placing infected trout into three different water temperature tanks: 12°C, 15°C and 19°C, whereby the development of RMS was monitored microscopically and by taking samples and images of the lesions,” explains Mr. Orioles.

“We found that higher water temperatures of 15°C and 19°C caused the disease to reach a severity peak sooner, and the skin lesions started to heal quicker in comparison to water temperatures of 12°C. At 19°C RMS skin lesions developed in only a few cases,” he adds.

“The project identified a strong association between MLO and the presence of these lesions,” explains Mr Orioles. “This was a very important achievement of the study.”

Fish skin tissue was also assessed via electron microscopy to visualise the bacteria inside the lesions. “This is where MSD Animal Health UK’s generous contribution was vital.

“Thanks to MSD Animal Health UK we were able to perform electron microscopy analysis, which we otherwise wouldn’t have been able to afford, nor could we have collected the kind of data we achieved,” states Mr. Orioles.

He went on to explain that this enabled a new polymerase chain reaction (PCR) technique, known as digital droplet PCR, to be established. This method of diagnosis is much more sensitive than typical PCR tests and will detect even the tiniest of DNA strains of the MLO bacteria, making it easier to monitor its presence in the environment.

Fish will experience varying degrees of water temperature throughout their lifecycle, and so these findings can help farmers in decisions relating to different temperature strategies to help control and manage the disease.

“The studies established a strong association between MLO and the disease and supported us in developing a new method of diagnostics,” explains Mr. Orioles.

Commenting on the findings of this study, Rebecca Rivara, Business Unit Director for Integrated Livestock at MSD Animal Health UK, said:

“MSD Animal Health UK is delighted to have awarded Mr. Orioles the research bursary, and it’s great to see that the outcomes have been so successful. The project has provided valuable insight into RMS and will help future development of disease prevention tools and techniques which will support the industry.”

The project was a collaboration between MSD Animal Health UK, University of Udine and the National Institute of Aquatic Resources (DTU). A link to the published research papers can be found here: Effect of temperature on transfer of Midichloria-like organism and development of red mark syndrome in rainbow trout (Oncorhynchus mykiss) – ScienceDirect

Development and application of a sensitive droplet digital PCR for the detection of red mark syndrome infection in rainbow trout (Oncorhynchus mykiss) – ScienceDirect