Megalocytivirus infection in orbiculate batfish Platax orbicularis

Megalocytiviruses cause systemic disease in both marine and freshwater fishes, neg- atively impacting ornamental and food fish aquaculture. In this report, we characterize a megalo- cytivirus infection in a captive marine ornamental fish, the orbiculate batfish Platax orbicularis. Histologic examination revealed cytomegalic cells characterized by strongly basophilic granular intracytoplasmic inclusions within various organs. Transmission electron microscopy revealed icosahedral virus particles within the cytoplasm of cytomegalic cells consistent with an iridovirus infection. Analysis of the major capsid protein gene sequence confirmed that the orbiculate batfish virus is a member of the family Iridoviridae and is identical to the only other megalocytivirus reported from a marine ornamental fish, the Banggai cardinalfish Pterapogon kauderni iridovirus.