Ranavirus infections associated with skin lesions in lizards

Abstract

Ranaviral disease in amphibians has been studied intensely during the last decade, as associated mass-mortality events are considered to be a global threat to wild animal populations. Several studies have also included other susceptible ectothermic vertebrates (fish and reptiles), but only very few cases of ranavirus infections in lizards have been previously detected. In this study, we focused on clinically suspicious lizards and tested these animals for the presence of ranaviruses. Virological screening of samples from lizards with increased mortality and skin lesions over a course of four years led to the detection of ranaviral infections in seven different groups. Affected species were: brown anoles (Anolis sagrei), Asian glass lizards (Dopasia gracilis), green anoles (Anolis carolinensis), green iguanas (Iguana iguana), and a central bearded dragon (Pogona vitticeps). Purulent to ulcerative-necrotizing dermatitis and hyperkeratosis were diagnosed in pathological examinations. All animals tested positive for the presence of ranavirus by PCR and a part of the major capsid protein (MCP) gene of each virus was sequenced. Three different ranaviruses were isolated in cell culture. The analyzed portions of the MCP gene from each of the five different viruses detected were distinct from one another and were 98.4-100% identical to the corresponding portion of the frog virus 3 (FV3) genome. This is the first description of ranavirus infections in these five lizard species. The similarity in the pathological lesions observed in these different cases indicates that ranaviral infection may be an important differential diagnosis for skin lesions in lizards.

Figure 1

Ranavirus infected Asian glass lizard (Dopasia gracilis). (A): skin lesions on the ventral surface of the body. (B): brown crusted skin lesions on the dorsum.

Figure 2

Histopathological skin lesion (ulcerative dermatitis) of a ranavirus infected Asian glass lizard (Dopasia gracilis). Note the intralesional fungal hyphae invading the dermis. 400 × PAS stain.

Figure 3

Skin alterations observed in ranavirus infected green anoles (Anolis carolinensis). (A): beige gray discoloration of the skin at the lateral abdomen. (B): multiple ulcera on the ventral abdominal surface. (C): grayish lesions on the skin of the tail.

Figure 4

Skin lesions in a ranavirus infected central bearded dragon (Pogona vitticeps). (A): pustules on the skin in the region of the neck and the head (August 2011); (B): skin alterations on the head and neck (same animal as Figure 4A in October 2012).

Figure 5

Histopathological skin proliferation of a ranavirus infected central bearded dragon (Pogona vitticeps). Note the irregularly distributed iridophores and the large melanocytes. 400 × Van Gieson stain; polarized light. 1: melanocytes, 2: horny layer, 3: epidermis, 4: iridophores (white iridescence), 5: connective tissue fibres (red), x: indentations of the normal skin, the right one is bordering the pathological areas.