“First detection of the Fancy-Tailed Guppy Virus (FTGV) in Europe (7356)”

First detection of the Fancy-Tailed Guppy Virus (FTGV) in Europe

Introduction: The Fancy-Tailed Guppy Virus (FTGV) is a pathogen of the guppy (Poecilia reticulata) and a new member of the emerging Amnoonviridae family of viruses, which are proving to be some of the most virulent and dangerous for fish. Due to its segmented genome, the virus may be prone to recombination, which can affect infectivity and complicate diagnostics. Until now, the virus has been detected in the USA in fish populations originating from Asia and South America, in both clinically affected and healthy fish. As the guppy is widely used as an ornamental pet and a biological model, health surveillance programmes are needed.

Methodology: Samples were collected from guppies presented for examination over one month after a disease outbreak leading to a large-scale die-off. These fish were collected from an undisclosed ornamental fish retailer and originated from an ornamental fish breeder in Asia. They did not display any clinical signs of infection. Additional samples were collected from clinically healthy, unrelated, laboratory-raised experimental populations with no history of health problems, originating from South America. Classical virological methods such as cell culture-based virus cultivation and a range of qPCR and RT-qPCR assays were employed in combination with metabarcoding of bacterial populations (Nanopore 16S sequencing) and immune response profiling to identify the agent causing the disease and mortality. Further targeted FTGV testing was performed to confirm the absence of the pathogen in fish from the laboratory-raised experimental populations.

Results: A total of five batches of fish from the retailer and five lab-raised populations were tested. Two populations originating from the disease outbreak were confirmed to be positive for FTGV, with high or moderate Ct values indicating persistent subclinical infection. The virus was re-isolated using E-11 cells. Partial genome sequencing and phylogenetic analysis revealed significant variation in the FTGV isolates. No clear indication of the involvement of pathogenic bacteria was detected. Evaluation of immune responses was not helpful due to the late subclinical phase of the infection. The laboratory-raised experimental populations were confirmed to the FTGV-free.

Conclusions: This study confirms the presence of FTGV in guppy populations associated with a major mortality event. It highlights the potential for persistent subclinical infection and significant genetic variability of the virus and emphasises the need for targeted surveillance and biosecurity measures in the ornamental fish trade.

1. ADAMEK, MIKOLAJ, UNIVERSITY OF VETERINARY MEDICINE HANNOVER, Presenter
2. Ramirez Stoll, Tamara, UNIVERSITY OF VETERINARY MEDICINE HANNOVER, Author
3. Debnath, Dipa, UNIVERSITY OF VETERINARY MEDICINE HANNOVER, Author
4. Krebs, Torben, UNIVERSITY OF VETERINARY MEDICINE HANNOVER, Author
5. Korytar, Tomas, Laboratory of Fish Immunology, Institute of Parasitology, Biology Centre CAS, Ceske Budejovice, Czechia, Author
6. Falco, Alberto, Fish Pathology Group, Institute of Aquaculture Torre de La Sal-Spanish National Research Council (IATS-CSIC), Cabanes, Castell&a, Author
7. Soto, Esteban, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA, Author
8. Rakus, Krzystof, Department of Evolutionary Immunology, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, Author
9. Herdegen-Radwan, Magdalena, Department of Behavioural Ecology, Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Poznan, P, Author
10. Radwan, Jacek, Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland, Author
11. Jung-Schroers, Verena, UNIVERSITY OF VETERINARY MEDICINE HANNOVER, Author