Novel Herpesvirus Associated With Oropharyngeal Squamous Cell Carcinoma in Smooth Green Snakes (Opheodrys vernalis)

Novel herpesvirus in the critically endangered Galapagos pink land iguana

Virus surveillance in wildlife is important to understanding ecosystem health, taxonomy, and evolution. Nevertheless, viruses in reptiles, and specifically in squamates, continue to be understudied. Herein, we conducted a health assessment on the critically endangered Galapagos pink land iguana (Conolophus marthae) and the vulnerable Galapagos land iguana (Conolophus subcristatus). We collected oral and/or cloacal swabs from 47 clinically healthy iguanas and tested for adenovirus (cloacal swabs, n = 47) and herpesvirus (oral swabs, n = 45) using broad-spectrum PCRs. Two out of 38 (5.3 %) Galapagos pink land iguanas tested positive for herpesvirus, while no herpesvirus was detected in all Galapagos land iguanas (n = 7). Both herpesviral sequences were identical between them and divergent (61.9 % amino acid identity) when compared to the closest herpesvirus sequences available in GenBank/EMBL/DDBJ. The genetic distance between this and other herpesviruses is consistent with its classification as a novel virus species. All iguanas were negative for adenovirus. This is the first description of a herpesvirus in iguanas of the Galapagos islands, and the first report of a potential pathogen for the iconic Galapagos pink land iguana. Further research is needed to understand the implications of this virus in the conservation and management of one of the most endangered iguana species in the world.

A NOVEL IGUANID HERPESVIRUS DETECTED IN ASYMPTOMATIC GREEN IGUANAS (IGUANA IGUANA) IN POLAND

While herpesviruses are well-known pathogens in a wide variety of chelonian species, they have only sporadically been documented in squamate reptiles. Those that have been described have most often been associated with hepatic disease and oral lesions. During a study on infectious disease in pet reptiles in Poland, herpesviruses were detected in swabs from three green iguanas (Iguana iguana) from two different owners that were presented to two different veterinary clinics in Warsaw. One iguana was presented for abscesses on the head, while the other two were partner animals and remained clinically healthy throughout the course of this study. Virus was detected in oral swabs as well as combined swab samples from the oral cavity and cloaca using a panherpesvirus PCR. PCR products from all three animals were sequenced, and the detected viruses were most closely related to iguanid herpesvirus 2 from a San Esteban chuckwalla (Sauromalus varius) in the United States (GenBank accession No. AY236869.1). The single animal was retested again 1 y later and remained clinically healthy and continued to shed the same herpesvirus. This is the first description of a herpesvirus infection in pet iguanas in Europe. While the clinical relevance of the infection is not known, it is of interest that the infected animals appeared to continue to shed virus over an extended period of time.

Herpesviruses in Reptiles

Since the 1970s, several species of herpesviruses have been identified and associated with significant diseases in reptiles. Earlier discoveries placed these viruses into different taxonomic groups on the basis of morphological and biological characteristics, while advancements in molecular methods have led to more recent descriptions of novel reptilian herpesviruses, as well as providing insight into the phylogenetic relationship of these viruses. Herpesvirus infections in reptiles are often characterised by non-pathognomonic signs including stomatitis, encephalitis, conjunctivitis, hepatitis and proliferative lesions. With the exception of fibropapillomatosis in marine turtles, the absence of specific clinical signs has fostered misdiagnosis and underreporting of the actual disease burden in reptilian populations and hampered potential investigations that could lead to the effective control of these diseases. In addition, complex life histories, sampling bias and poor monitoring systems have limited the assessment of the impact of herpesvirus infections in wild populations and captive collections. Here we review the current published knowledge of the taxonomy, pathogenesis, pathology and epidemiology of reptilian herpesviruses.

Detection of a novel herpesvirus associated with squamous cell carcinoma in a free-ranging Blanding's turtle

The spread of both infectious and noninfectious diseases through wildlife populations is of increasing concern. Neoplastic diseases are rarely associated with population-level impacts in wildlife; however, impacts on individual health can be severe and might reflect deteriorating environmental conditions. An adult male free-ranging Blanding's turtle (Emydoidea blandingii) originally captured in 2005 and deemed healthy, was recaptured in 2018 with a 1 × 1.5 cm intra-oral broad-based right mandibular mass. An excisional biopsy was performed, and histopathology revealed squamous cell carcinoma (SCC). Consensus herpesvirus PCR identified a novel herpesvirus (proposed name Emydoidea herpesvirus 2 [EBHV-2]) within the tumor. EBHV-2 shares 85% sequence homology with Terrapene herpesvirus 2 (TerHV-2), a herpesvirus linked to fibropapillomas in eastern box turtles (Terrapene carolina carolina). Virus-associated fibropapillomas have been identified in multiple marine turtle species and have had debilitating effects on their populations, but to date, virus-associated SCCs are rarely reported.