Abstract
Herpesviruses are important pathogens in tortoises and turtles, yet little is known about the epidemiology of these viruses. We analyzed herpesviruses detected by PCR in samples from captive chelonians in Europe according to virus strain, host species, year and season in which the animal was tested, and country in which the animal was kept. A total of 4,797 samples submitted to a diagnostic laboratory in Europe between January 2016 and December 2020 were evaluated. Of these, 312 (6.50%) were positive for herpesviruses. The types most commonly found were testudinid herpesvirus (TeHV)1 (143 positive, 45.83%) and TeHV3 (153 positive, 49.04%), but also included TeHV2 (1 positive, 0.32%), TeHV4 (3 positive, 0.96%), Terrapene herpesvirus 1 (7 positive, 2.24%), Trachemys herpesvirus 1 (2 positive, 0.64%), and three previously undescribed herpesviruses (0.96%). Herpesviruses were detected in chelonians in the families Testudinidae, Emydidae, Geoemydidae, and in the suborder Pleurodira. Among the species for which 100 samples or more were available, the highest proportions of positive samples (positivity rates) were found in samples from Horsfield's tortoises (Testudo horsfieldii) (14.96%), and radiated tortoises (Astrochelys radiata) (14.05%). Among tortoises (Testudinidae), viruses were most often detected in the spring, while in emydid turtles (Emydidae) they were most often detected in the summer. A comparison of the positivity rates according to country showed significant differences, with the highest rate in samples from Italy (16.01%). This study indicated possible differences in herpesvirus positivity rates depending on host species, virus strain, year of sampling, season, and country of origin. It provides useful information in further understanding fluctuations in infection rates as well as in helping to guide decision making for herpesvirus diagnostics in chelonian patients. It also provides evidence for the international dispersal of herpesviruses with their hosts through international trade.
Highlights
Herpesviruses are among the most commonly described viruses in chelonians
143 were positive for TeHV1 (45.83%; 95% confidence interval (CI) 40.39–51.38%), one for TeHV2 (0.32%; 95% CI 0.06– 1.79%), 153 for Testudinid alphaherpesvirus 3 (TeHV3) (49.04%; 95% CI 43.54–54.56%), 3 for TeHV4 (0.96%; 95% CI 0.33–2.79%), 7 for Terrapene herpesvirus 1 (2.24%; 95% CI 1.09–4.55%), 2 for Trachemys herpesvirus 1 (0.64%; 95% CI 0.18–2.31%), and 3 for other alphaherpesviruses (0.96%; 95% CI 0.33–2.79%) (Table 1)
The sequence obtained from that sample was 100% identical to that from a herpesvirus found in a panther chameleon (Furcifer pardalis) (GenBank accession No MW015088.1) and did not cluster with members of the Scutavirus genus [43]
Summary
Herpesviruses are among the most commonly described viruses in chelonians Herpesviruses found in these animals that have been genetically analyzed have clustered together in the subfamily Alphaherpesvirinae, in the genus Scutavirus [1–3]. Herpesviruses found in sea turtles (family Cheloniidae) include Chelonid alphaherpesvirus 5 which is associated with fibropapillomatosis [3, 5, 6]. Lung-eye-trachea-disease-associated virus (LETV) was originally described in green turtles (Chelonia mydas) with respiratory disease [7]. It is categorized in the species Chelonid alphaherpesvirus 6 [4], and is related to the members of the genus Scutavirus, but has not been assigned to a genus yet. Other herpesviruses described in sea turtles include gray patch disease virus found in juvenile green turtles with skin lesions [8]. Analysis of sequences from a part of the DNA-dependent DNApolymerase gene showed that both clustered with members of the genus Scutavirus [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
