New disease records for hatchery-reared sturgeon. I. Expansion of frog virus 3 host range into Scaphirhynchus albus

Abstract

In 2009, juvenile pallid sturgeon Scaphirhynchus albus, reared at the Blind Pony State Fish Hatchery (Missouri, USA) to replenish dwindling wild stocks, experienced mass mortality. Histological examination revealed extensive necrosis of the haematopoietic tissues, and a virus was isolated from affected organs in cell culture and then observed by electron microscopy. Experimental infection studies revealed that the virus is highly pathogenic to juvenile pallid sturgeon, one of several species of sturgeon currently listed as Endangered. The DNA sequence of the full length major capsid protein gene of the virus was identical to that of the species Frog virus 3 (FV3), the type species for the genus Ranavirus, originally isolated from northern leopard frog Lithobates pipiens. Although FV3 infections and epizootics in amphibians and reptiles are well documented, there is only 1 prior report of a natural infection of FV3 in fish. Our results illustrate the broad potential host range for FV3, with the known potential to cause significant mortality in poikilothermic vertebrates across 3 taxonomic classes including bony fishes, anuran and caudate amphibians, and squamate and testudine reptiles.

Distribution and Host Range of Ranaviruses

“…Furthermore, FV3 outbreaks have impeded efforts to restore populations of the critically endangered pallid sturgeon ( Scaphirhynchus albus ) in the Missouri River Basin of the USA . High-mortality epizootics were reported among young-of-the-year pallid sturgeon in 2001, 2009, and 2013 at the Blind Pony Hatchery in Sweet Springs, Missouri, USA (Chinchar and Waltzek 2014 ;Waltzek et al 2014 ). Experimental transmission of the 2009 isolate recreated the same high-mortality disease in naïve juvenile pallid sturgeon following bath exposure .…”

“…Recently, SCRV and FV3 have been repeatedly detected among hatchery-reared freshwater fi shes in North America and Asia (Woodland et al 2002b ;Prasankok et al 2005 ;Deng et al 2011 ;George et al 2014 ;Chinchar and Waltzek 2014 ;Waltzek et al 2014 ). Two genetically distinct but related ranaviruses, Singapore grouper iridovirus (SGIV) and grouper iridovirus (GIV), have negatively impacted grouper mariculture in Asia since the 1990s (Chua et al 1994 ;Murali et al 2002 ;Qin et al 2003 ).…”

Ranavirus Ecology and Evolution: From Epidemiology to Extinction

“…Johnson et al ( 2007 ) could only induce infections in a box turtle ( Terrepene ornata ornata ) and several redeared sliders with intramuscular injections of Burmese star tortoise ranavirus, but those that were orally exposed to the same dose remained uninfected. More recently, however, Brenes et al ( 2014a ) demonstrated water-borne transmission of an FV3-like ranavirus isolated from pallid sturgeon ( Scaphirhynchus albus ; Waltzek et al 2014 ) to red-eared sliders: 20 % of turtles that were bath exposed and 30 % of turtles co-housed with infected Cope's gray treefrog ( H. chrysoscelis ) became infected. It should also be noted that transmission by arthropod vectors has not been ruled out.…”

Comparative Pathology of Ranaviruses and Diagnostic Techniques

“…2a ; Waltzek et al 2014 ), and fi sh may have red swollen gills . Internally, hemorrhages may occur in any organ including the fat bodies and swim bladder, and organs may be friable (Fig.…”