Genetic Analysis of Betanodaviruses in Subclinically Infected Aquarium Fish and Invertebrates

Betanodaviruses causing viral nervous necrosis (VNN) have been detected and isolated from several species of cultured marine fish worldwide. In Korea, VNN was identified in several species of cultured marine fish. This study presents data on the amplified nested PCR product (420 bp) of 11 nodavirus strains from different species of apparently healthy aquarium fish and invertebrates collected in one private commercial aquarium in Korea. Phylogenetic analyses based on the partial nucleotide sequence (177 bases) of the RNA2 coat protein gene were identical to the redspotted grouper nervous necrosis virus (RGNNV) genotype (96%–100%). The presence of the RGNNV type of betanodaviruses in these subclinically infected aquarium fish and invertebrates imported from different countries probably indicates that the samples were contaminated inside the aquarium and represents a serious challenge for its management of viral nervous necrosis. These positive samples can be an inoculum source of betanodavirus infection to other susceptible fish species inside the aquarium.This work was supported by a Korea Research Foundation Grant (KRF-2006-005-E00076) and the Research Institute for Veterinary Science. We are also thankful to Dr. T. Nakai, Hiroshima University, Japan, for kindly providing the E-11 cell line for virus isolation