Isolation and characterization of an iridovirus from Hermann’s tortoises (Testudo hermanni)

Abstract

A virus was isolated from tissues of 2 diseased Hermann's tortoises (Testudo hermanni) and preliminarily characterized as an iridovirus. This conclusion was based on the presence of inclusion bodies in the cytoplasm of infected cells, sensitivity to chloroform, inhibition of virus replication by 5-iodo-2'-desoxyuridine and the size and icosahedral morphology of viral particles. The virus was able to replicate in several reptilian, avian and mammalian cell lines at 28 degrees C, but not at 37 degrees C. Restriction enzyme analysis showed resistance of the ral DNA to digestion with HpaII due to methylation of the internal cytosine at CCGG sequences. Part of the genomic region encoding the major capsid protein was amplified by PCR and subjected to sequence analysis. Comparative analysis of the obtained nucleotide sequence revealed that the isolate is closely related to frog virus 3, the type species of the genus Ranavirus.

Distribution and Host Range of Ranaviruses

“…In addition to the box turtle cases described above, several other reports of FV3-like infections have been seen in captive chelonians (Marschang et al 1999 ;De Voe et al 2004 ;Benetka et al 2007 ;Johnson et al 2008 ;Blahak and Uhlenbrok 2010 , Table 4 ). Ranavirus infections were described in two juvenile diseased Hermann's tortoises ( Testudo hermanni ) in Germany using PCR.…”

“…Ranavirus infections were described in two juvenile diseased Hermann's tortoises ( Testudo hermanni ) in Germany using PCR. All seven animals in the affected group died with similar signs (Marschang et al 1999 ). The associated virus was fi rst described as FV3-like, but has since been shown to be more closely related to CMTV (Stöhr et al 2015 ).…”

Ranavirus Infection of Free-Ranging and Captive Box Turtles and Tortoises in the United States

“…The histologic lesions in the chelonians in this report were relatively nonspecific; intracytoplasmic basophilic inclusion bodies that could be suggestive of iridovirus infection (Heldstab and Bestetti, 1982;Bollinger et al, 1999;Marschang et al, 1999;Docherty et al, 2003) were present in just five of nine cases. Clinical and pathologic differential diagnoses for the animals in this report before the confirmation of iridoviruses by molecular methods, virus isolation, and/or TEM, included septicemia, based on the fibrinous splenitis and multicentric vasculitis, and chelonian herpesvirus infection (Johnson et al, 2005), based on the lesions of necrotizing stomatitis.…”

“…The mixtures were amplified in a thermal cycler (PCR Sprint, Thermo Hybaid, Ashford, Middlesex, UK) with an initial denaturation at 94 C for 2.5 min, followed by 25 cycles of denaturation at 94 C for 30 sec. ; annealing at 50 C for 30 sec; extension at 72 C for 30 sec., and a final extension step at 72 C for 10 min, as previously described (Marschang et al, 1999). The same extracted DNA from the chelonian tissues was evaluated by PCR for the presence of chelonian herpesvirus(es).…”

“…Iridovirus infections have also been sporadically described in reptiles, including snakes (Hyatt et al, 2002), lizards (Marshang et al, 2005) and chelonians. In chelonians, iridovirus infections have been reported in captive Hermann's tortoises (Testudo hermanni; Heldstab et al, 1982;Muller et al, 1988;Marschang et al, 1999), farmed softshelled turtles (Chen et al, 1999) and captive eastern box turtles (Terrapene carolina carolina ;De Voe et al, 2004). Two ranaviruses identified in an exotic tortoise (Testudo horsfieldii) and a box turtle in the United States were found to be closely related to frog virus 3 (FV3) and designated as tortoise virus 5 (TV5) and turtle virus 3 (TV3), respectively (Mao et al, 1997).…”