Detection and molecular characterization of infectious spleen and kidney necrosis virus from major ornamental fish breeding states in P eninsular M alaysia

‘Gold standard’ OIE reference PCR assay was utilized to detect the presence of infectious spleen and kidney necrosis virus ( ISKNV ) in freshwater ornamental fish from M alaysia. From total of 210 ornamental fish samples representing 14 species, ISKNV was detected in 36 samples representing 5 fish species. All positive cases did not show any clinical signs of ISKNV . Three restriction enzymes analyses showed that the fish were infected by identical strains of the same virus species within M egalocytivirus genus. Major capsid protein ( MCP ) genes of 10 ISKNV strains were sequenced and compared with 9 other reference nucleotide sequences acquired from G en B ank. Sequence analysis of MCP gene showed that all strains detected in this study were closely related to the reference ISKNV with nucleotide sequence identity that was ranging from 99.8% to 100%. In addition, phylogenetic analysis of MCP gene revealed that viruses from genus M egalocytivirus can be divided into three genotypes: genotype 1 include reference ISKNV and all other strains that were detected in this study, genotype 2 include viruses closely related to red sea bream iridovirus ( RSIV ), and genotype 3 include viruses closely related turbot reddish body iridovirus ( TRBIV ).