Ranaviruses and reptiles

Wirth, Wytamma; Schwarzkopf, Lin; Skerratt, Lee F.; Ariel, Ellen

doi:10.7717/peerj.6083

Cited by 23 publications

(24 citation statements)

References 117 publications

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“…Basking, a possible form of behavioural fever, was observed more frequently in higher dose groups; however, the thermal potential was not assessed, and turtles may have just been escaping the water and not thermoregulating [31]. Skin lesions reported in our study have not been reported in other turtle challenge studies, but external skin lesions are often reported in lizards with ranaviral infections [3] and ulceration has been reported in a ranaviral infection of eastern box turtles [32]. Skin lesions were only found in the i.m.…”

Section: Discussioncontrasting

confidence: 54%

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Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae)

Wirth

Schwarzkopf

Skerratt

et al. 2019

Journal of General Virology

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Ranaviral infections cause mass die-offs in wild and captive turtle populations. Two experimental studies were performed to first determine the susceptibility of an Australian turtle species (Emydura macquarii krefftii) to different routes of infection and second examine the effect of viral titre on the morbidity in hatchlings. All inoculation routes (intracoelomic, intramuscular and oral) produced disease, but the clinical signs, histopathology and time to onset of disease varied with the route. The median infectious and lethal doses for intramuscularly inoculated hatchlings were 102 . 52 (1.98–2.93) and 104.43 (3.81–5.19) TCID50 ml−1, respectively. Clinical signs began 14 to 29 days post-inoculation and the median survival time was 22 days (16–25) across all dose groups. For every 10-fold increase in dose, the odds of developing any clinical signs or severe clinical signs increased by 3.39 [P<0.01, 95 % confidence interval (CI): 1.81–6.36] and 3.71 (P<0.01, 95 % CI: 1.76–7.80), respectively. Skin lesions, previously only reported in ranaviral infection in lizards, were observed in the majority of intramuscularly inoculated hatchlings that developed ranaviral disease. The histological changes were consistent with those in previous reports for reptiles and consisted of necrosis at or near the site of injection, in the spleen, liver and oral cavity. Systemic inflammation was also observed, predominantly affecting necrotic organs. The estimates reported here can be used to model ranaviral disease and quantify and manage at-risk populations.

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Section: Discussioncontrasting

confidence: 54%

“…For the most part, ranaviral disease research has focused on fish and amphibians, but these viruses also cause disease in wild and captive reptile species around the world, often resulting in high levels of mortality [2]. The most common group of reptiles to be reported with ranaviral disease are turtles (order Testudines) [3].…”

Section: Introductionmentioning

confidence: 99%

Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae)

Wirth

Schwarzkopf

Skerratt

et al. 2019

Journal of General Virology

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“…Given the importance of microbiomes in both human health [14, 15] and emerging infectious diseases in groups like amphibians [16–18], it is likely that microbiomes are important for turtle health as well. Furthermore, Ranavirus infections are of particular concern for turtles [19] and Ranavirus infections are negatively associated with higher microbial richness in amphibians [20], suggesting that microbiomes may be able to mitigate infections.…”

Section: Introductionmentioning

confidence: 99%

Microbiome diversity and composition varies across body areas in a freshwater turtle

et al. 2020

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There is increasing recognition that microbiomes are important for host health and ecology, and understanding host microbiomes is important for planning appropriate conservation strategies. However, microbiome data are lacking for many taxa, including turtles. To further our understanding of the interactions between aquatic microbiomes and their hosts, we used next generation sequencing technology to examine the microbiomes of the Krefft’s river turtle (Emydura macquarii krefftii). We examined the microbiomes of the buccal (oral) cavity, skin on the head, parts of the shell with macroalgae and parts of the shell without macroalgae. Bacteria in the phyla Proteobacteria and Bacteroidetes were the most common in most samples (particularly buccal samples), but Cyanobacteria , Deinococcus-thermus and Chloroflexi were also common (particularly in external microbiomes). We found significant differences in community composition among each body area, as well as significant differences among individuals. The buccal cavity had lower bacterial richness and evenness than any of the external microbiomes, and it had many amplicon sequence variants (ASVs) with a low relative abundance compared to other body areas. Nevertheless, the buccal cavity also had the most unique ASVs. Parts of the shell with and without algae also had different microbiomes, with particularly obvious differences in the relative abundances of the families Methylomonaceae, Saprospiraceae and Nostocaceae . This study provides novel, baseline information about the external microbiomes of turtles and is a first step in understanding their ecological roles.

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“…Reptile ranaviruses have a multispecies host range, and therefore reptile-specific PCR assays are not required (Wirth et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

Evidence for low prevalence of ranaviruses in Ontario, Canada’s freshwater turtle population

Carstairs¹

2019

PeerJ

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Background Ontario, Canada is home to eight native species of turtles; all eight are federally listed as Species At Risk, due to anthropogenic threats. However, until recently, reports of infectious disease have been lacking. Ranavirus is seen as an emerging threat for ectotherms globally, with mass die-offs most often reported in amphibians. Ranavirus has been detected in Ontario’s amphibian populations, can be transmitted via water, and can be transmitted from amphibians to turtles. However, no studies on the prevalence of this virus in Ontario’s turtles have previously been carried out. With recent reports of two confirmed positive case of ranavirus in turtles in Ontario, a knowledge of the ecology of ranavirus in Ontario’s turtles has become even more important. This study estimates the prevalence of ranavirus in Ontario’s turtles, and investigates the hypothesis that this is a newly emergent disease. Methods Sixty-three samples were tested for ranavirus via PCR. These included a variety of turtle species, across their home range in Southern Ontario. Fifty-two of the samples originated from the liver and kidney of turtles who had succumbed to traumatic injuries after being admitted to the Ontario Turtle Conservation Centre; ten of the samples were taken from cloacal swabs, lesion swabs, or tail clips collected from live turtles showing signs of clinical disease. One of the live turtles was later euthanized for humane reasons and PCR was also carried out on the liver/kidney. Results None of the 63 samples were found to be positive for ranavirus via PCR. The zero prevalence found in this study translates into a population prevalence estimate of less than 5%, with no change in prevalence from 2014–2018. Discussion This is the first report on the prevalence of ranavirus in Ontario’s turtles, and will help build an understanding of the ecology of this virus in Ontario. Ranavirus has historically been underreported in reptiles, but there has been an increase in global reports recently, most likely due to increased awareness. A carrier state is thought to exist in reptiles which makes surveillance in the population via random sampling a viable method of detection of prevalence. The first report of ranavirus in Ontario turtles occurred in 2018. This study suggests a continued low population prevalence for the years 2014–2018, however. Ongoing surveillance is necessary, as well as investigation of the eDNA presence in waterways as compared to the PCR of resident turtles, to further understand the sensitivity of these species to ranavirus infection. The utilization of qPCR would be helpful, to better quantify any positives encountered.

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Ranaviruses and reptiles

Cited by 23 publications

References 117 publications

Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae)

Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae)

Microbiome diversity and composition varies across body areas in a freshwater turtle

Evidence for low prevalence of ranaviruses in Ontario, Canada’s freshwater turtle population

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