In the USA and in Hungary, almost simultaneously, adenoviruses of a putative
novel lineage were detected by PCR and sequencing in turtles belonging to four
different species (including two subspecies) of the superfamily Testudinoidea. In the
USA, partial sequence of the adenoviral DNA-dependent DNA polymerase was
obtained from samples of a captive pancake tortoise (Malacochersus tornieri), four
eastern box turtles (Terrapene carolina carolina) and two red-eared sliders (Trachemys
scripta elegans). In Hungary, several individuals of the latter subspecies as well as some
yellow-bellied sliders (T. s. scripta) were found to harbor identical, or closely related,
putative new adenoviruses. From numerous attempts to amplify any other genomic
fragment by PCR, only a nested method was successful, in which a 476-bp fragment of
the hexon gene could be obtained from several samples. In phylogeny reconstructions,
based on either DNA polymerase or hexon partial sequences, the putative new
adenoviruses formed a clade distinct from the five accepted genera of the family
Adenoviridae. Three viral sub-clades corresponding to the three host genera
(Malacochersus, Terrapene, Trachemys) were observed. Attempts to isolate the new
adenoviruses on turtle heart (TH-1) cells were unsuccessful. Targeted PCR screening of live and dead specimens revealed a prevalence of approximately 25% in small shelter
colonies of red-eared and yellow-bellied sliders in Hungary. The potential pathology of
these viruses needs further investigation; clinically healthy sliders were found to shed
the viral DNA in detectable amounts. Based on the phylogenetic distance, the new
adenovirus lineage seems to merit the rank of a novel genus