Isolation of a lethal virus from the endangered tiger salamander Ambystoma tigrinum stebbinsi

Abstract

The Sonora tlger salamander Ambystoma tignnuni stebb~nsi Lowe is a genetically d~stinct race restricted to about 30 small ponds in the San Rafael Valley 111 southern Arizona, USA, which was added recently to the USA Federal List of Endangered Species Populations of these salamanders periodically expenence decimating epizootics. Virus was ~solated from diseased salamanders using fish cell cultures, injected into healthy laboratory-reared salamanders, and then reisolated in cell culture. Electron microscopy of thin sections from dying salamanders revealed abundant enveloped and nonenveloped icosahedral virus particles approximately 160 to 180 nm in diameter in the cytoplasm of skin and liver cells and free in the intercellular spaces. This virus, believed to be an iridovirus based on viral morphology and host pathology, was demonstrated to be the primary pathogen in these epizootics, and is the first lethal epizootic virus reported from salamanders. We have named the virus Ambystoma tigrinum Virus (ATV). Hemolytic bacteria were isolated from sick individuals, but we were unable to induce the disease by exposing salamanders to isolated bacteria at concentrations up to 10' ml-' KEY WORDS: Salamander. Ambystoma tigrinum stebbinsi. Virus. Indovirus. Amphibian decline

Antimicrobial Peptide Defenses in the Salamander, Ambystoma Tigrinum, Against Emerging Amphibian Pathogens

“…Our results closely agree with observations of diseases of A. tigrinum in the field. This species does not generally die of B. dendrobatidis even when heavily infected (Davidson et al, 2003b), but is readily killed by low concentrations of ATV (Jancovich et al, 1997;Brunner et al, 2004Brunner et al, , 2005.…”

“…Peptide-virus preparations were then diluted in MEM with 2% FBS and a standard plaque assay using EPC cells was performed. Plaques in replicate wells were counted and averaged after approximately 2 wk incubation at 18 C (Jancovich et al, 1997). Activity of the peptide preparations is FIGURE 1.…”

“…At the same time, another group of diseases caused by ranaviruses (Iridoviridae) have led to massive localized dieoffs of frogs and salamanders in North America and Europe (Carey, 2000;Daszak et al, 1999Daszak et al, , 2000Collins and Storfer, 2003). Ambystoma tigrinum is highly susceptible to ranavirus infection (Jancovich et al, 1997). The apparently recent emergence of both B. dendrobatidis and ranaviruses suggests that the immune defenses of susceptible species may not be effective against these newly emergent pathogens Carey, 2000;.…”

“…Ambystoma tigrinum virus (ATV), a ranavirus related to frog virus 3, causes mortality in many species of salamanders (A. tigrinum, Ambystoma gracile, Ambystoma mexicanum) and newts (Notophtalamus viridescens) (Jancovich et al, 1997(Jancovich et al, , 2001Davidson et al, 2003a). The ATV is responsible for localized die-offs of A. tigrinum across western North America .…”

LOW DETECTION OF RANAVIRUS DNA IN WILD POSTMETAMORPHIC GREEN FROGS, RANA (LITHOBATES) CLAMITANS, DESPITE PREVIOUS OR CONCURRENT TADPOLE MORTALITY

“…Ranaviruses (Iridoviridae) can infect a variety of species of amphibians, fish, and reptiles, but there is some host-dependent susceptibility: Frog Virus 3 (FV3) usually, but not exclusively, infects frogs and toads (Chinchar, 2002) wheras Ambystoma tigrinum virus (ATV) tends to cause infection in salamanders (Jancovich et al, 1997). Infection causes acute mortality of tadpoles (98-100%), and can result in severe dermal and visceral lesions and death of adults (Greer and Collins, 2007;Cunningham et al, 2008).…”