• Journal of fish pathology
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• v.19 no.3
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• pp.197-206
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• 2006

The distribution of iridoviruses in five freshwater ornamental fishes, pearl gourami (Trichogaster leeri), dwarf gourami (Colisa lalia), silver gourami (Trichogaster microlepis), blue gourami (Trichogaster trichopterus sumatranus) and freshwater angelfish (Pterophyllum scalare), imported from Singapore was examined in 2004 and 2005. The presence of iridoviruses in 56 sample groups was determined using PCR technique and showed PCR positive in 11 sample groups. The proportion of fish infected by iridovirus was differed depending upon species; 31.8% (7/22) for pearl gourami, 18.2% (2/11) for dwarf gourami, 16.7% (1/6) for blue gourami, 9.1% (1/11) for silver gourami and 0% (0/6) for angelfish. In quantitative comparison of viral DNAs isolated from infected tissues, the DNA concentration of iridovirus in pearl gourami was higher than that in dwarf gourami. Although pearl gourami infected naturally by iridovirus showed 100% mortality in keeping experiment for 3 weeks, only 57% of those was positive in PCR. In the comparison of nucleotide sequences of the PstⅠ fragment known as the most variable genomic region, both iridoviruses isolated from pearl gourami and dwarf gourami showed identity more than 99% with infectious spleen and kidney necrosis virus (ISKNV) isolated from mandarinfish (Siniperca chuatsi).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.352-358
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• 2011

The presence of ISKNV-like viruses in various freshwater ornamental fish species imported from Asia was confirmed by polymerase chain reaction(PCR) amplification of the ATPase(adenosine triphosphatase) gene. Interestingly, molecular analyses of the Open Reading Frame 25(ORF25) region of these isolates based on the ISKNV(Infectious spleen and kidney necrosis virus) genome revealed the presence of various repetitive sequences. ORF25 repeat sequence length had no effect on cumulative mortality of rock bream Oplegnathus fasciatus challenged with tissue homogenates of infected pearl gourami, Trichogaster leeri; silver gourami, Trichogaster microlepis; blue gourami, or Trichogaster trichopterus. All isolates induce cumulative mortalities after 12 days of infection, confirming that ORF25 polymorphism did not affect the pathogenicity of ornamental fish megalocytiviruses that cross infect rock bream, a seawater fish. Also, no statistically significant differences in spleen index or viral copy number in infected tissues was detected between isolates with varying ORF25 repeat sequence lengths. However, further studies are necessary to fully characterize the functional characteristics of these polymorphisms in megalocytivirus disease in ornamental fishes.