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TDK conference 2023Berta Péter Patrik - year 6 University of Veterinary Medicine Budapest, Department of Microbiology and Infectious Diseases Supervisors: Dr. Tibor Papp, Dr. András Marosi Research of chelonid (i.e., turtle) viruses is still a marginal field. Their most important pathogens belong to the family Herpesviridae, which often decimate protected species; yet members of Adenoviridae have also been found in such disease outbreaks. Only a small percentage of the described viruses have their complete genome sequences determined, e.g., from the over a dozen adenovirus types, not even one. Despite this, it was still possible to create a new genus (Testadenovirus) for the adenoviruses of turtles (Testudines). The aim of our study was to detect herpesviruses and adenoviruses from 33 specimens died in pet shops, representing 17 species of turtles. In positive cases, we genetically characterised the viruses, and attempted the full genome characterisation of one of the adenoviruses. The carcasses were dissected, and DNA extracted from samples of internal organs was then subjected to degenerate nested PCRs targeting the DNA polymerase gene for both kinds of viruses. Specific-size PCR products were sequenced and the sequences were subjected to BLAST homology searches against the NCBI database. A Chinese pond turtle (Mauremys reevesii), a Russian tortoise (Testudo horsfieldii), a Hermann’s tortoise (Testudo hermanni), a striped mud turtle (Kinosternon baurii), a West African mud turtle (Pelusios castaneus) and a Greek tortoise (Testudo graeca) tested positive for herpesvirus. The virus found in the Greek tortoise showed 97% nucleotide identity with the GenBank testudinid alphaherpesvirus 3 sequence, while the sequences from the other individuals were 99.5% identical to testudinid alphaherpesvirus 1. Two Indian star tortoises (Geochelone elegans), one leopard tortoise (Stigmochelys pardalis) and two Chinese pond turtles tested positive for adenovirus. Two previously unknown viruses, belonging to the genus Testadenovirus, were found in four of the above cases: one in the two Indian star tortoises and the leopard tortoise, and the other one in a Chinese pond turtle. Furthermore, in another Chinese pond turtle, a virus belonging to the genus Siadenovirus, described earlier as a major cause of severe disease in the critically endangered Sulawesi tortoise, was detected. An attempt was also made to determine the whole-genome of one of the testadenoviruses using the Illumina method, but unfortunately without success. However, PCRs targeting the hexon gene of testadenoviruses and sequencing of their products were successful. Furthermore, I was able to confirm the hypothesis of our research group, by comparative phylogenetic analysis (tanglegram), that known members of the genus Testadenovirus (current number is 19) and their host species (15) have followed a parallel evolutionary (coevolutionary) pathway. List of lectures |