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TDK conference 2016

Genetic analysis of an adenovirus detected in a green anole (Anolis carolinensis)
Vadász Gergő - year 5
CAR Hungarian Academy of Sciences, Institute for Veterinary Medical Research
Supervisors: Dr. Mária Benkő, Zoltán László Tarján


Adenoviruses (Family: Adenoviridae, AdV) are medium-sized, non-enveloped viruses, with icosahedral nucleocapsid, double-stranded DNA genome. They are cosmopolitan viruses which have been found in members of every vertebrate class. They usually show strong host specificity, however one host could be infected with more AdV-types. The filogenetic trees showing the filiation of AdVs and their hosts have very similar, which could be the result of a long co-evolution progress. The Adenoviridae family contains five genera. Most of the reptile-infectious AdVs belongs to the Atadenovirus genus, which supposes the Squamata origin of the genus. Infections are mostly asymptomatic, or it manifests in a mild upper respiratory or gastrointestinal disease. Sometimes it may severe outcome.

The aim of my work was to examine reptile samples for AdV-infections, and the genetical characterization of the viruses.

My samples come from dead and living reptiles, in form of internal organs and feces. After the DNA-extraction I used for the screening a consensus, nested PCR to amplify a 320 bp long part of the DNA-dependent DNA-polymerase. To do gene mapping we choose a few genes (IVa2, III, pVII, hexon and 100K) which I tried to amplify, using genus-specific primers we already had in the lab and some designed by myself. I got positive results from IVa2, pVII, hexon and 100K. I connected these parts by using specific primers and simple PCR, after that I used primer walking to determine the nucleic acid sequence.I made a phylogenetic reconstruction with maximum likelihood method based on the partial sequences of the polymerase and hexon genes.

To this time I screened 55 samples and got 15 positive results of which 12 were some already published and known sequences. One green and one brown anole contained a new AdV, I continued with the detailed analysis of the one from the green anole. I managed to amplify the middle region of the genome between the IVa2 and the hexon, which counted 14771 nt and had a balanced G+C content (51.48%). According to the gene bank, based on the partial DNA-polymerase sequence, it’s in a close relationship with the Anole 2 AdV (57% identity, 72% similarity in amino acids) and other atadenoviruses. The phylogenetic reconstructions based on the partial hexon and polymerase sequence also confirmed its affiliation to the Atadenoviridae genus.

Due to our research, we think thet the examined AdV did not went through a host-switch, but it’s the product of a long co-evolution procedure, therefore it’s a “real” anolis AdV.

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