EXPERIMENTAL DEMONSTRATION OF THE PATHOGENICITY OF A FROG VIRUS, BOHLE IRIDOVIRUS, FOR A FISH SPECIES, BARRAMUNDI-LATES-CALCARIFER

Experimental infections indicate that Bohle iridovirus, a Ranavirus, is pathogenic for barramundi Lates calcarifer Bloch. Mortalities after bath-exposure or inoculation of barramundi in both freshwater and seawater were 100 %. Symptoms of inoculated barramundi held in seawater and freshwater and bath-exposed barramundi in freshwater included cessation of feeding, shivering, loss of muscle coordination, spiral and often erratic swimming and decreased ventilation. Just prior to death, the fish were incapable of any movement. In bath-exposed barramundi held in seawater, no symptoms were observed before death. The infection was characterised by focal to diffuse necrosis of the haematopoietic tissue of the kidney and spleen. In several BIV-infected barramundi, focal necrosis occurred in the liver. In bath-exposed and inoculated barramundi, BIV was isolated on BF2 cell monolayers from muscle, liver, kidney and spleen tissues, with recovery rates of 72.5, 58.5, 17.7 and 17.7 % respectively. This is the first time that a virus isolated from a frog has been shown to cause mortalities in a fish species.