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TDK conference 2018

Hypothetically viral tumours of intensively bred sturgeons
Józsa Emőke - year 5
University of Veterinary Medicine Budapest, Department of Exotic Animal and Wildlife Medicine
Supervisors: Dr. Ferenc Baska, Réka Borzák


Tissue distortions manifested by tumours have been known to mankind since ancient times. The earliest official record about human tumours may be a note of Imhotep, who was the high priest of Ra sun-god and served for Djoser belonged to the Third Dynasty of Egyptian Pharaohs, in the 27th century BC.

The particular description and registration of animal tumours have become relevant just in the Modern Period of human history. One of the first scientific documentation that reported about bone tumours in fish was published in 1793.

Our study is based on the case of a fish farm located in western Hungary, where on the body surface of fish in the Siberian sturgeon (Acipenser baerii) stock, tumours had developed then disappeared. The progress of the disease, in account the literature data, took suspicion of virus infection proposed.

In our work, we studied totally 23 tissue samples excised from liver, spleen, kidney, tumour, heart and gills of 11 fish, which were moribund or conserved by frozen or in formalin.

For the molecular works, we isolated both genomic DNA and RNA from the specimens using commercial kits according to the manufacturers' instructions. We wanted to detect different tumour associated viruses (DNA viruses: (ds) herpes-, adeno-, irodovirus, and (ss) circovirus; as well as RNA viruses: (ds) aquareovirus, and (ss) retrovirus) by classical and reverse‐transcription‐coupled‐PCR methods.

We attempted to isolate the presumable infectious agents by artificial infection of cells using the filter-sterilized tissue homogenate of studied fish’s organs. For the virus propagation, we used sturgeon- specific cell lines, such as SSO-2 (Siberian Sturgeon Organs-2) and WSS-2 (White Sturgeon Spleen-2).

In the PCR assays, several DNA bands in the expected fragment size-range were managed to multiplicate. Nevertheless, during the sequencing, none of them presented significant similarity with nucleotide- or predicted amino acid sequences of any known virus genomes in the database of the National Center for Biotechnology Information.

Although we detected a cytopathogenic effect on the cell lines in the initial stage of in vitro infections, it was not able to transfer to following passages. Thus the cell destruction observed us earlier may be considered a result of the effect of the cytopathogenic substances released from the organs.

In conclusion, the fact that we did not manage to isolate any known viruses during our executed trials; it does not exclude the presence of these agents. The role of viruses in the induction of tumour formation and progression is known and proven in many cases, in accordance with literature data. Therefore, further studies on this topic applying by new methods are required.

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