A New Ranavirus Isolated from Pseudacris clarkii Tadpoles in Playa Wetlands in the Southern High Plains, Texas

Abstract

Mass die-offs of amphibian populations pose a challenging problem for conservation biologists. Ranaviruses often cause systemic infections in amphibians and, in North America, are especially virulent and lethal to larvae and metamorphs. In this paper we describe a novel ranavirus isolate as well as the first recorded occurrence of ranavirus in the southern High Plains of Texas and in associated populations of the spotted chorus frog Pseudacris clarkii. The breeding sites were playas, that is, wetlands that fill via isolated thunderstorms that can occur infrequently; thus, not every playa has water or breeding amphibians annually. We did not detect ranavirus in sympatric anurans, but other reports document ranaviruses in Pseudacris spp. elsewhere. The occurrence of multiple isolates of ranavirus in a number of Pseudacris species suggests that this genus of frogs is highly susceptible to ranaviruses and may experience exceptionally high mortality rates from infection. Thus, the virus may contribute to substantial seasonal population declines and low seasonal recruitment, with negative impacts on populations of breeding adults in successive years.

Ranavirus Ecology and Evolution: From Epidemiology to Extinction

“…Ranavirus was not detected until late April, when 20 % of the larvae were infected and increased to a high of 80 % twenty days later, which coincided with a die-off of ambystomatid larvae. The rapid increase in the prevalence of infection signs in spotted chorus frog ( Pseudacris clarkii ) tadpoles collected by Torrence et al ( 2010 ) is also consistent with this model. Indeed, mortality events generally coincide with high infection prevalence (Bollinger et al 1999 ;Greer et al 2005 ;Fox et al 2006 ;Kik et al 2011 ;Hoverman et al 2012 ;Homan et al 2013 ;Titus and Green 2013 ).…”

Major capsid protein gene sequence analysis of the Santee-Cooper ranaviruses DFV, GV6, and LMBV

“…2009, Mazzoni et al 2009, Hoverman et al 2010, Torrence et al 2010, Whittington et al 2010, Xu et al 2010. Recent reports about ranavirus outbreaks in Pseudacris clarkii tadpoles in Texas underline the subject's topicality (Torrence et al 2010), since the decline of amphibian populations is a severe problem on a global scale.…”

“…In the meantime, additional pathogenic ranaviruses have been isolated from various poikilothermic vertebrates: Ambystoma tigrinum virus (ATV) isolated 1996 from Sonora tiger salamanders Ambystoma tigrinum stebbinsi in southern Arizona; European catfish virus (ECV), recovered since 1990 in France and Italy; European sheatfish virus (ESV), first detected in 1989 in Germany; Bohle iridovirus (BIV), isolated in 1992 from Australian frogs Limnodynastes ornatus, and SanteeCooper rana viruses isolated from guppy Poecilia reticulata, doctor fish Labroides dimidatus, and largemouth bass Micropterus salmoides in the 1990s in the United States (Ahne et al 1989, Pozet et al 1992, Bovo et al 1993, Hedrick & McDowell 1995, Jancovich et al 1997, Plumb et al 1996, Ariel & Owens 1997, Grizzle et al 2002, Goldberg et al 2003. Thus, ranaviruses have been isolated worldwide from fish, amphibians, and reptiles at an increasing frequency over the last few decades (Chinchar 2002, Duffus et al 2008, Johnson et al 2008, Chinchar et al 2009, Gray et al 2009, Mazzoni et al 2009, Hoverman et al 2010, Torrence et al 2010, Whittington et al 2010, Xu et al 2010. Recent reports about ranavirus outbreaks in Pseudacris clarkii tadpoles in Texas underline the subject's topicality (Torrence et al 2010), since the decline of amphibian populations is a severe problem on a global scale.…”

“…2009, Mazzoni et al 2009, Hoverman et al 2010, Torrence et al 2010, Whittington et al 2010, Xu et al 2010. Recent reports about ranavirus outbreaks in Pseudacris clarkii tadpoles in Texas underline the subject's topicality (Torrence et al 2010), since the decline of amphibian populations is a severe problem on a global scale.While EHN and ranavirus infection of amphibians were listed as notifiable diseases in 2006 (Anonymous 2006), other ranavirus infections of fish, caused by ESV/ECV, PPIV, shortfin eel ranavirus (SERV), or Santee-Cooper ranaviruses, and the reptile ranavirus soft shelled turtle iridovirus (SSTIV) have thus far not been listed by the European Union nor by the World Organisation for Animal Health (Office International des Épi-zooties, OIE). In the light of the current knowledge on the significant genetic similarity and broad host range of ranaviruses, further discussion about the declaration and listing of ranavirus infections as exotic diseases in the EU is necessary.…”

Co-infection by alveolate parasites and frog virus 3-like ranavirus during an amphibian larval mortality event in Florida, USA

“…), FV3-like ranavirus has not been associated with amphibian die-offs in Florida. Throughout the rest of North America, FV3 and FV3-like viruses have been identified as the cause of widespread amphibian mortality events (Chinchar 2002, Green et al 2002, Converse & Green 2005, Fauquet et al 2005, Greer et al 2005, Harp & Petranka 2006, Duffus et al 2008, Torrence et al 2010, Brunner et al 2011, Lesbarrères et al 2012. In Florida, FV3-like viruses have been reported from a gopher tortoise Gopherus polyphemus and a Florida box turtle Terrapene carolina bauri (Johnson et al 2008) but not from amphibians.…”