Abstract

A newly recognized iridovirus was found to be infecting the integument of the juvenile white sturgeon Acipenser transmontanus . Only epithelial cells in the skin and gills were infected. Infected cells were enlarged and often very basophilic. Virions with a mean diameter of 262 nm were found within infected cells. In heavy infections, the skin and gills of dead and moribund fish showed numerous infected cells. No other pathogens were detected in sturgeon that succumbed to the disease, and it is likely that the virus was the cause of the mortality. A laboratory study indicated that the virus could be transmitted via water to uninfected white sturgeon held below infected fish.